JP6242431B2 - Image processing apparatus and method, and image display apparatus - Google Patents

Description

  The present invention relates to an image processing apparatus and method for performing enhancement processing on an input image, and an image display apparatus using the same. For example, when an enlarged image obtained by enlarging an original image is input as an input image, Image enhancement processing is performed so as to obtain an output image with high resolution by generating and adding frequency components.

  In general, an image signal representing an image is appropriately subjected to image processing and then reproduced and displayed.

  For example, in the image processing apparatus described in Patent Document 1, a first intermediate image obtained by extracting a component in the vicinity of a specific frequency band of an input image is generated, and the second intermediate image is generated based on the first intermediate image. And the input image and the second intermediate image are added.

JP 2010-34959 A (FIG. 1)

  However, in the above-described image processing apparatus, when the input image includes a pattern in which a periodic pattern moves, the enhancement processing becomes inappropriate and an output image with an appropriate image quality cannot be obtained. This is due to the following reason.

  In the related art, when the input image includes a periodic pattern, the luminance difference between the bright part and the dark part becomes larger in the corresponding part. Therefore, when the periodic pattern included in the input image moves, the luminance of each pixel included in the corresponding portion periodically changes between a bright state and a dark state. Here, when the luminance difference between the case where the pixel is bright and the case where the pixel is bright is extremely large according to the conventional technique, it seems that the pixel blinks periodically. That is, as a result of processing by the prior art, a portion where a periodic pattern has moved may blink partially, and in such a case, it is visually uncomfortable.

第ｎの値Ｄ（ｎ）は以下の式で表され、

第ｊの値Ｄ（ｊ）（２≦ｊ≦ｎ−１）は以下の式で表され、

さらに、
前記分割データ処理手段は、上記の式で表されるｎ個の値Ｄ（ｊ）のうち、第２の値Ｄ（２）から前記第ｎの値Ｄ（ｎ）までのｎ−１個の値のうち、少なくとも一つを減衰させる
ことを特徴とする。 Images processing device of the present invention,
Intermediate image generating means for generating a first intermediate image obtained by extracting a component in the vicinity of a specific frequency band of the input image;
Intermediate image processing means for receiving the first intermediate image and generating a second intermediate image;
Correction means for receiving the second intermediate image as input and outputting a corrected image obtained by correcting the second intermediate image;
First adding means for adding the input image and the corrected image;
The correction means includes
The pixel value of the second intermediate image is converted into code data representing a code of the pixel value and first divided data obtained by dividing the absolute value of the pixel value into n values (n is an integer of 2 or more). A dividing means for dividing;
Divided data processing means for generating second divided data consisting of n values in which at least one value is attenuated among the n values constituting the first divided data;
The value obtained by adding the n values constituting the second divided data, have a synthesizing means for outputting a value obtained by adding a code indicating said code data,
When the absolute value of the pixel value is D and n−1 thresholds satisfying TH (j) ≦ TH (j + 1) are represented by TH (j) (j = 1 to n−1),
Of the n values D (j) (j = 1 to n) constituting the first divided data,
The first value D (1) is represented by the following equation:

The nth value D (n) is represented by the following equation:

The j-th value D (j) (2 ≦ j ≦ n−1) is expressed by the following equation:

further,
The divided data processing means includes n-1 values from the second value D (2) to the nth value D (n) among the n values D (j) represented by the above formula. At least one of the values is attenuated .

  According to the present invention, for example, it is possible to prevent partial blinking that may occur when a moving pattern input as an input image includes a pattern that moves periodically.

It is a block diagram which shows the structure of the image processing apparatus by Embodiment 1 of this invention. It is a block diagram which shows the structural example of the intermediate image production | generation means of FIG. It is a block diagram which shows the structural example of the intermediate image process means of FIG. It is a block diagram which shows the structural example of the horizontal direction nonlinear processing means 2Ah of FIG. It is a block diagram which shows the structural example of the vertical direction nonlinear processing means 2Av of FIG. It is a block diagram which shows the structural example of the correction | amendment intensity | strength determination means 3 of FIG. (A)-(C) is a figure which shows operation | movement of the horizontal direction comparison means 3Ah of FIG. 6, and the horizontal direction comparison result addition means 3Bh. (A)-(C) is a figure which shows operation | movement of the vertical direction comparison means 3Av of FIG. 6, and the vertical direction comparison result addition means 3Bv. It is a block diagram which shows the structural example of the correction | amendment means 4 of FIG. FIG. 10 is a block diagram illustrating a configuration example of a correction amount determination unit 4 </ b> A in FIG. 9. It is a figure which shows an example of the input-output characteristic of horizontal direction correction amount determination means 4Ah of FIG. It is a block diagram which shows the structural example of the image display apparatus using the image processing apparatus of FIG. It is a block diagram which shows the structural example of the image expansion means U1 of FIG. (A)-(E) is a pixel arrangement | positioning figure which shows operation | movement of the image expansion means U1 of FIG. (A)-(E) are the frequency response figure and frequency spectrum figure which show the operation | movement of the image expansion means U1 of FIG. (A)-(E) are the frequency response figure and frequency spectrum figure which show operation | movement of the intermediate | middle image production | generation means 1. FIG. (A)-(C) are the frequency response figure and frequency spectrum figure which show the operation | movement of the intermediate | middle image processing means 2 of FIG. (A)-(C) is a figure which shows the value of the signal of the pixel which continues when a step edge and a step edge are sampled by sampling interval S1. (A)-(C) is a figure which shows the value of the signal of the pixel which continues when a step edge and a step edge are sampled by sampling interval S2. It is a figure which shows operation | movement of the intermediate image production | generation means 1 and the intermediate image processing means 2. FIG. 6 is a diagram illustrating an operation of the image processing apparatus according to Embodiment 1. FIG. FIG. 6 is a diagram illustrating an operation when an image with a cyclic pattern is input to the image processing apparatus according to the first embodiment. It is a figure which shows the image processing result by the image processing apparatus by Embodiment 1 in the location where a periodic pattern moves. It is a block diagram which shows the other structural example of the correction | amendment intensity | strength determination means 3 of FIG. (A) And (B) is a figure which shows the example from which the input-output characteristic from which the comparison means 3A of the correction | amendment intensity | strength determination means 3 of FIG.6 and FIG.24 differs is different. It is a block diagram which shows the structure of the image processing apparatus by Embodiment 2 of this invention. It is a block diagram which shows the structural example of the correction | amendment means 40 of FIG. (A) And (B) is a figure which shows operation | movement of the correction | amendment means 40. FIG. It is a block diagram which shows the structure of the image processing apparatus by Embodiment 3 and 4 of this invention. FIG. 10 is a block diagram illustrating a configuration example of an intermediate image processing unit 20 according to a third embodiment. FIG. 10 is a block diagram illustrating an exemplary configuration of an intermediate image processing unit 20 according to a fourth embodiment. It is a flowchart which shows the process sequence of the image processing method by Embodiment 5 of this invention. FIG. 33 is a flowchart showing a processing procedure of intermediate image generation step ST1 of FIG. 32. FIG. 33 is a flowchart showing a processing procedure of intermediate image processing step ST1 of FIG. 32. It is a flowchart which shows the process sequence of horizontal direction nonlinear process step ST2Ah of FIG. It is a flowchart which shows the process sequence of vertical direction nonlinear process step ST2Av of FIG. FIG. 33 is a flowchart showing a processing procedure of a correction strength determination step ST3 in FIG. 32. It is a flowchart which shows the process sequence of correction | amendment step ST4 of FIG. It is a flowchart which shows the process sequence of correction amount determination step ST4A of FIG. FIG. 33 is a flowchart showing a processing procedure in another example of the correction strength determination step ST3 of FIG. 32. It is a flowchart which shows the process sequence of the image processing method by Embodiment 6 of this invention. It is a flowchart which shows the process sequence of correction | amendment step ST40 of FIG. It is a flowchart which shows the process sequence of the image processing method by Embodiment 7 and 8 of this invention. It is a flowchart which shows the process sequence of intermediate | middle image process step ST20 of FIG. 43 in Embodiment 7. FIG. FIG. 44 is a flowchart showing a processing procedure of intermediate image processing step ST20 of FIG. 43 in the eighth embodiment.

Embodiment 1 FIG.
FIG. 1 shows the configuration of an image processing apparatus according to Embodiment 1 of the present invention. The illustrated image processing apparatus can be used as a part of an image display apparatus, for example.

The illustrated image processing apparatus includes an intermediate image generation unit 1, an intermediate image processing unit 2, a correction intensity determination unit 3, a correction unit 4, and an addition unit 5.
The intermediate image generating means 1 generates an intermediate image (first intermediate image) D1 obtained by extracting components near a specific frequency band of the input image DIN.
The intermediate image processing means 2 generates an intermediate image (second intermediate image) D2 obtained by performing processing described later on the intermediate image D1.

The correction strength determination means 3 determines a correction strength D3 obtained by performing processing to be described later on the intermediate image D1, and outputs data representing the correction strength. Hereinafter, the data representing the correction strength may be simply referred to as correction strength, and is represented by the same symbol D3.
The correcting unit 4 outputs a corrected image D4 obtained by performing processing to be described later based on the intermediate image D2 and the correction strength D3.

The adding means 5 adds the input image DIN and the corrected image D4. The addition result by the adding means 5 is output as an output image DOUT.
In the following description, it is assumed that the input image DIN input to the illustrated image processing apparatus is a moving image composed of a series of images.
The detailed configuration and operation of the image processing apparatus according to the first embodiment will be described below.

  For example, as shown in FIG. 2, the intermediate image generating unit 1 includes a high frequency component image generating unit 1A and a low frequency component image generating unit 1B.

  The high frequency component image generating unit 1A generates an image D1A obtained by extracting only the high frequency component of the input image DIN. High frequency components can be extracted by performing high-pass filter processing. Here, extraction of the high frequency component is performed in each of the horizontal direction and the vertical direction of the image. That is, the high-frequency component image generating unit 1A performs horizontal high-pass filter processing on the input image DIN to generate an image D1Ah in which the high-frequency component is extracted only in the horizontal direction. And vertical direction high frequency component image generation means 1Av that performs high-pass filter processing in the vertical direction to generate an image D1Av obtained from high frequency components only in the vertical direction, and the image D1A is composed of an image D1Ah and an image D1Av.

  The low frequency component image generation means 1B generates an image D1B obtained by extracting only the low frequency component of the image D1A. The low frequency component can be extracted by performing a low pass filter process. The low frequency component is extracted in each of the horizontal direction and the vertical direction. That is, the low-frequency component image generation unit 1B performs horizontal low-frequency component image generation unit 1Bh that generates an image D1Bh obtained by performing horizontal low-pass filter processing on the image D1Ah, and vertical low-pass filter processing on the image D1Av. Vertical direction low frequency component image generation means 1Bv for generating the performed image D1Bv, and the image D1B is composed of an image D1Bh and an image D1Bv.

  From the intermediate image generating means 1, the image D1B is output as the intermediate image D1. Here, the intermediate image D1 includes an image D1h corresponding to the image D1Bh and an image D1v corresponding to the image D1Bv. In the intermediate image generating means 1, the high-frequency component image generating means 1A and the low-frequency component image generating means 1B constitute a band pass filter means. Further, the image D1h is an image obtained by band-limiting the input image DIN in the horizontal direction, and the image D1v is an image obtained by band-limiting the input image DIN in the vertical direction.

  The intermediate image processing means 2 will be described. FIG. 3 shows a configuration example of the intermediate image processing means 2. The illustrated intermediate image processing means 2 includes a nonlinear processing means 2A, a high frequency component image generating means 2B, and an adding means 2C that outputs an image D2C obtained by adding the intermediate image D1 and the image D2B.

  The nonlinear processing means 2A outputs an image D2A obtained by performing nonlinear processing described later on the intermediate image D1. Here, the nonlinear processing performed by the nonlinear processing means 2A is performed in each of the horizontal direction and the vertical direction. That is, the non-linear processing means 2A performs a non-linear process described later on the image D1Bh to generate an image D2Ah, and a vertical non-linear process generates a picture D2Av by performing a non-linear process described later on the image D1Bv. The image D2A includes an image D2Ah and an image D2Av.

  The operation of the nonlinear processing means 2A will be described in more detail. The nonlinear processing means 2A includes a horizontal nonlinear processing means 2Ah and a vertical nonlinear processing means 2Av having the same configuration. Here, the horizontal nonlinear processing means 2Ah performs horizontal processing, and the vertical nonlinear processing means 2Av performs vertical processing.

  FIG. 4 shows an example of the configuration of the horizontal nonlinear processing means 2Ah. The illustrated horizontal non-linear processing means 2Ah includes a zero-cross determining means 311h and a signal amplifying means 312h. Note that the image D1h is input to the horizontal nonlinear processing means 2Ah as the input image DIN311h.

  The zero-cross determining unit 311h checks the change in the pixel value in the input image DIN 311h along the horizontal direction. Then, a point where the pixel value changes from a positive value to a negative value or from a negative value to a positive value is regarded as a zero cross point, and the positions of the pixels before and after the zero cross point (pixels adjacent in the front and back) are determined by the signal D311h. The signal is transmitted to the signal amplifying means 312h. For example, pixels located on the left and right of the zero cross point are recognized as pixels located before and after the zero cross point.

  Based on the signal D311h, the signal amplifying unit 312h identifies pixels before and after the zero cross point (adjacent pixels before and after the zero cross point), and amplifies the pixel value only for the pixels before and after the zero cross point (the absolute value is increased). A nonlinear processed image D312h is generated. That is, the amplification factor is set to a value larger than 1 for the pixel values of the pixels before and after the zero cross point, and the amplification factor for the pixel values of the other pixels is set to 1.

  A non-linearly processed image D312h is output as an image D2Ah from the horizontal non-linear processing means 2Ah.

  FIG. 5 shows a configuration example of the vertical nonlinear processing means 2Av. The illustrated vertical non-linear processing means 2Av includes a zero-cross determining means 311v and a signal amplifying means 312v. Note that the image D1v is input to the vertical nonlinear processing means 2Av as the input image DIN311v.

  The zero-cross determination unit 311v confirms the change of the pixel value in the input image DIN 311v along the vertical direction. Then, a point where the pixel value changes from a positive value to a negative value or from a negative value to a positive value is regarded as a zero cross point, and the position of pixels (adjacent pixels in the front and rear) before and after the zero cross point is determined by the signal D311v. This is transmitted to the signal amplifying means 312v. For example, pixels positioned above and below the zero cross point are recognized as pixels positioned before and after the zero cross point.

  Based on the signal D311v, the signal amplifying unit 312v identifies pixels before and after the zero cross point (adjacent pixels before and after the zero cross point), and amplifies the pixel value only for the pixels before and after the zero cross point (the absolute value is increased). A nonlinear processed image D312v is generated. That is, the amplification factor is set to a value larger than 1 for the pixel values of the pixels before and after the zero cross point, and the amplification factor for the pixel values of the other pixels is set to 1.

Then, the nonlinear processed image D312v is output as the image D2Av from the vertical nonlinear processing means 2Av.
The above is the operation of the nonlinear processing means 2A.

  The high frequency component image generation unit 2B generates an image D2B obtained by extracting only the high frequency component of the image D2A. High frequency components can be extracted by performing high-pass filter processing. Note that high frequency components are extracted in the horizontal and vertical directions of the image. That is, the high-frequency component image generation unit 2B performs horizontal high-frequency component image generation unit 2Bh that generates an image D2Bh obtained by performing horizontal high-pass filter processing on the image D2Ah, and performs vertical high-pass filter processing on the image D2Av. Vertical direction high frequency component image generation means 2Bv for generating the performed image D2Bv, and the image D2B includes the image D2Bh and the image D2Bv.

The adding means 2C adds the intermediate image D1 and the image D2B to generate an image D2C. The intermediate image D1 is composed of the image D1h and the image D1v, and the image D2B is composed of the image D2Bh and the image D2Bv. Therefore, when the intermediate image D1 and the image D2B are added, the images D1h, D1v, D2Bh, and D2Bv It means adding all. Here, the addition processing in the adding means 2C is not limited to simple addition, and weighted addition may be used. That is, the images D1h, D1v, D2Bh, and D2Bv may be added after being amplified at different amplification factors.
From the intermediate image processing means 2, the image D2C is output as the intermediate image D2.

  The correction strength determination unit 3 will be described. FIG. 6 shows a configuration example of the correction strength determining means 3. The illustrated correction strength determination unit 3 includes a comparison unit 3A and a comparison result addition unit 3B.

  The comparison unit 3A compares the absolute value of the pixel value with a predetermined threshold for each pixel of the intermediate image D1, and outputs the result as a comparison result D3A. That is, the output value obtained as the comparison result D3A is 1 when the absolute value of the pixel value of the intermediate image D1 is greater than a predetermined threshold value, and is 0 otherwise. Since the intermediate image D1 includes the images D1h and D1v, the comparison with the threshold value is performed for each of the images D1h and D1v. That is, the comparison unit 3A includes a horizontal direction comparison unit 3Ah that performs processing to be described later on the image D1h, and a vertical direction comparison unit 3Av that performs processing to be described later on the image D1v. The comparison result D3A is a horizontal direction comparison unit. The comparison result D3Ah output by 3Ah and the comparison result D3Av output by the vertical comparison means 3Av. Hereinafter, the operations of the horizontal direction comparison unit 3Ah and the vertical direction comparison unit 3Av will be further described.

  The horizontal direction comparing means 3Ah compares the absolute value of the pixel value with a predetermined threshold value for each pixel of the image D1h, and outputs the result as a comparison result D3Ah. The output value obtained as the comparison result D3Ah is 1 when the absolute value of the pixel value of the image D1h is greater than a predetermined threshold value, and is 0 otherwise. Here, the threshold value may be different depending on whether the sign of the pixel value of the image D1h is positive or negative.

  The vertical direction comparing means 3Av compares the absolute value of the pixel value with a predetermined threshold value for each pixel of the image D1v, and outputs the result as a comparison result D3Av. The output value obtained as the comparison result D3Av is 1 when the absolute value of the pixel value of the image D1v is larger than a predetermined threshold value, and is 0 otherwise. Here, the threshold value may be different depending on whether the sign of the pixel value of the image D1h is positive or negative.

  The comparison result adding means 3B adds the output values obtained as the comparison result D3A for a plurality of pixels, and outputs the result as the addition result D3B. In this addition, for each pixel (target pixel), an output value obtained as a comparison result D3A for a plurality of pixels located within a predetermined range centered on the target pixel is added. This addition processing is performed for each of the comparison results D3Ah and D3Av. That is, the comparison result addition unit 3B includes a horizontal direction comparison result addition unit 3Bh that performs processing described later on the comparison result D3Ah, and a vertical direction comparison result addition unit 3Bv that performs processing described later on the comparison result D3Av. The addition result D3B includes an addition result D3Bh output from the horizontal direction comparison result addition unit 3Bh and an addition result D3Bv output from the vertical direction comparison result addition unit 3Bv. Hereinafter, the operations of the horizontal direction comparison result adding unit 3Bh and the vertical direction comparison result adding unit 3Bv will be further described.

The horizontal direction comparison result adding means 3Bh adds the pixel values of the pixels existing within a predetermined range centered on the pixel to the comparison result D3Ah for each pixel, and outputs the result as an addition result D3Bh.
The vertical direction comparison result adding means 3Bv adds the pixel values of the pixels existing within a predetermined range centered on the pixel to the comparison result D3Av for each pixel, and outputs the result as an addition result D3Bv.

  7A to 7C are diagrams for explaining the operation of the horizontal direction comparison result adding means 3Bh. FIG. 7A shows the image D1h, FIG. 7B shows the comparison result D3Ah, and FIG. 7 (C) represents the addition result D3Bh. 7A to 7C show horizontal coordinates, vertical coordinates, and coordinate values according to the horizontal and vertical directions of the image.

  In FIG. 7A, the pixel value of the pixel at the position of the horizontal coordinate x and the vertical coordinate y is represented by the symbol D1h (x, y).

  FIG. 7B shows an example of the comparison result D3Ah obtained for the image D1h shown in FIG. In the example shown in FIG. 7B, D1h (2,1), D1h (2,2), D1h (4,2), D1h (4,3), D1h (2,4), D1h (3,4) ), The absolute value of D1h (4, 4) is larger than a predetermined threshold value.

  FIG. 7C shows an addition result (horizontal direction addition result) D3Bh obtained for the comparison result D3Ah shown in FIG. 7B. Here, when the addition result D3Bh is calculated, the value of the comparison result D3Ah in the range of two pixels on the left and right in the horizontal direction around each pixel is added. That is, the value of the comparison result D3Ah given to the pixel at the position of the horizontal coordinate x and the vertical coordinate y is represented by the symbol D3Ah (x, y), and for the pixel at the position of the horizontal coordinate x and the vertical coordinate y. When the value of the addition result D3Bh given in the above is expressed by the symbol D3Bh (x, y), D3Bh (x, y) is expressed by the following equation (1).

When the addition result D3Bh shown in FIG. 7C is calculated, the value of the comparison result D3Ah not shown in FIG. 7B, for example, D3Ah (1, 6), etc. is set to zero.
Here, the comparison results included in the range of two pixels on the left and right in the horizontal direction are simply added, but the addition method is not limited to simple addition but may be weighted addition. Further, the range used for addition is not limited to two pixels on the left and right.

  8A to 8C are diagrams for explaining the operation of the vertical direction comparison result adding means 3Bv. FIG. 8A shows the image D1v, FIG. 8B shows the comparison result D3Av, and FIG. 8 (C) represents the addition result D3Bv. 8A to 8C show horizontal coordinates, vertical coordinates, and coordinate values according to the horizontal and vertical directions of the image.

  In FIG. 8A, the pixel value of the pixel at the position of the horizontal coordinate x and the vertical coordinate y is represented by the symbol D1v (x, y).

  FIG. 8B shows an example of the comparison result D3Av obtained for the image D1v shown in FIG. In the example shown in FIG. 8B, D1v (2,1), D1v (2,2), D1v (4,2), D1v (4,3), D1v (2,4), D1v (3,4) ), The absolute value of D1v (4, 4) is larger than a predetermined threshold value.

  FIG. 8C shows an addition result (vertical addition result) D3Bv obtained for the comparison result D3Av shown in FIG. 8B. Here, when the addition result D3Bv is calculated, the value of the comparison result D3Av in the range of two pixels above and below in the vertical direction around each pixel is added. That is, the value of the comparison result D3Av given to the pixel at the position of the horizontal coordinate x and the vertical coordinate y is represented by the symbol D3Av (x, y), and for the pixel at the position of the horizontal coordinate x and the vertical coordinate y. When the value of the addition result D3Bv given in this way is represented by the symbol D3Bv (x, y), D3Bv (x, y) is represented by the following equation (2).

When the addition result D3Bv shown in FIG. 8C is calculated, the value of the comparison result D3Av not shown in FIG. 8B, for example, D3Av (1, 6) is set to zero.
Here, the comparison results included in the range of two pixels above and below in the vertical direction are simply added. However, the addition method is not limited to simple addition, and may be weighted addition. Furthermore, the range used for addition is not limited to the upper and lower two pixels.

Among the above, the horizontal direction comparison means 3Ah and the horizontal direction comparison result addition means 3Bh constitute a horizontal direction correction strength determination means 3h for obtaining the horizontal direction addition result D3Bh for each pixel, and the vertical direction comparison means 3Av and the vertical direction comparison. The result adding means 3Bv constitutes a vertical direction correction strength determining means 3v for obtaining a vertical direction addition result D3Bv for each pixel.
The addition result D3B composed of the horizontal direction addition result D3Bh and the vertical direction addition result D3Bv is output as the correction intensity D3 for each pixel.

  Since the addition result D3B includes the horizontal direction addition result D3Bh and the vertical direction addition result D3Bv, the correction strength D3 is the horizontal direction correction strength D3h corresponding to the horizontal direction addition result D3Bh and the vertical direction correction strength D3v corresponding to the vertical direction addition result D3Bv. Consists of.

  By operating the correction intensity determining means 3 as described above, the value of the correction intensity D3 is the absolute value of the pixel value in a location where the absolute value of the pixel value of the intermediate image D1 is large or in the vicinity thereof, or in the intermediate image D1. In areas or areas where many large pixels are gathered (hereinafter, these areas are referred to as “areas with high pixel density and high pixel distribution density”), the area is larger than 0, and in other areas it is 0. Become. That is, the correction intensity determination unit 3 detects a region with a high distribution density of pixels having a large absolute value of the pixel value of the intermediate image D1.

  The correction unit 4 will be described. FIG. 9 shows a configuration example of the correction means 4. The illustrated correction unit 4 includes a correction amount determination unit 4A and a correction calculation unit 4B.

The correction amount determining means 4A determines the correction amount D4A.
The correction amount D4A is calculated so as to be a large value in a region detected by the correction intensity determination means 3 when the distribution density of pixels having a large absolute value of the pixel value of the intermediate image D1 is high. For example, the correction amount D4A is obtained by a method of multiplying the correction strength D3 by a predetermined coefficient. Here, the coefficient multiplied by the correction strength D3 may be different depending on whether the sign of the pixel value of the intermediate image D2 is positive or negative.

  For example, as shown in FIG. 10, the correction amount determination unit 4A includes a horizontal direction correction amount determination unit 4Ah, a vertical direction correction amount determination unit 4Av, and an addition unit 4Ap. Details of the operation of the correction amount determination means 4A will be described below.

The horizontal direction correction amount determining means 4Ah obtains a horizontal direction correction amount D4Ah. Here, the horizontal direction correction amount D4Ah is obtained so as to be a large value in a region detected by the horizontal direction correction intensity determination means 3h when the distribution density of pixels having a large absolute value of pixel values is high. For example, the horizontal direction correction amount D4Ah is obtained by multiplying the horizontal direction correction strength D3h by a predetermined value. Here, the predetermined value to be multiplied by the correction intensity D3h is a value larger than 1, and is determined experimentally so that a desirable image is obtained, and when the pixel value of the intermediate image D2 is positive and negative Different values may be used.
As another method, when the horizontal direction correction strength D3h is less than a predetermined size, the horizontal direction correction amount D4Ah is 0, and the horizontal direction correction strength D3h is in the horizontal direction in at least a portion of the predetermined size or more. The correction amount D4Ah may be a value greater than or equal to a predetermined magnitude. For example, as shown in FIG. 11, when the horizontal correction intensity D3h is less than a predetermined magnitude THD3h, the horizontal correction amount D4Ah is 0, and the entire area of the section in which the horizontal correction intensity D3h is equal to or greater than the predetermined magnitude THD3h. The horizontal direction correction amount D4Ah may be a predetermined magnitude D4Ahc.

  The vertical direction correction amount determining means 4Av obtains the vertical direction correction amount D4Av. Here, the vertical direction correction amount D4Av is obtained so as to be a large value in a region detected by the vertical direction correction intensity determining means 3v when the distribution density of pixels having a large absolute value of pixel values is high. For example, the vertical direction correction amount D4Av can be obtained by multiplying the vertical direction correction strength D3v by a predetermined value. Here, the predetermined value multiplied by the correction intensity D3v is a value larger than 1, and is determined experimentally so that a desired image is obtained. The predetermined value is a case where the pixel value of the intermediate image D2 is positive. Different values may be used in negative cases.

  As another method, when the vertical direction correction strength D3v is less than a predetermined size, the vertical direction correction amount D4Av is 0, and the vertical direction correction strength D3v is vertical in at least a part of the predetermined size or more. The correction amount D4Av may be a value greater than a predetermined value. For example, the relationship between the vertical direction correction strength D3v and the vertical direction correction amount D4Av may be the same as the relationship between the horizontal direction correction strength D3h and the horizontal direction correction amount D4Ah shown in FIG.

The adding means 4Ap adds the horizontal direction correction amount D4Ah and the vertical direction correction amount D4Av. The addition result is output from the correction amount determining means 4A as the correction amount D4A.
The above is the operation of the correction amount determination unit 4A.

  The correction calculation means 4B corrects the pixel value of the intermediate image D2 based on the correction amount D4A. Here, the correction is performed so that the absolute value of the pixel value of the intermediate image D2 is reduced by the absolute value of the correction amount D4A. That is, when the pixel value of the intermediate image D2 is positive, the correction calculation means 4B subtracts the absolute value of the correction amount D4A from the value, and when the pixel value of the intermediate image D2 is negative, the correction calculation unit 4B calculates the absolute value of the correction amount D4A. Add the values. The output of the correction calculation means 4B is output from the correction means 4 as a corrected image D4.

  Considering that the correction amount D4A is calculated so as to be a large value in the detected region when the pixel density of the intermediate image D1 has a large absolute pixel value, the correction calculation unit 4B takes into account the intermediate image D1. Correction is performed so that the amplitude of the intermediate image D2 is attenuated in an area where the distribution density of pixels having a large absolute pixel value is high.

The adding means 5 will be described.
The adding means 5 adds the input image DIN and the corrected image D4. The addition result by the adding means 5 is output as an output image DOUT.
The above is the operation of the image processing apparatus according to the first embodiment of the present invention.

  Hereinafter, an example in which the image processing apparatus according to the present invention is used as a part of an image display apparatus will be described. Through this description, the operation and effect of the image processing apparatus according to the present invention will become clear. In the following description, unless otherwise specified, the symbol Fn represents the Nyquist frequency of the input image DIN.

  FIG. 12 shows an example of an image display apparatus using the image processing apparatus according to the present invention. In the illustrated image display device, an image corresponding to the original image DORG is displayed on the monitor U3.

  When the image size of the original image DORG is smaller than the image size of the monitor U3, the image enlargement unit U1 outputs an image DU1 obtained by enlarging the original image DORG. Here, a bicubic method or the like can be used as means for enlarging the image.

  The image processing apparatus U2 according to the present invention outputs an image DU2 obtained by performing the processing described above with reference to FIGS. 1 to 11 on the image DU1. The image DU2 is displayed on the monitor U8.

  Hereinafter, assuming that the number of pixels of the original image DORG is half the number of pixels of the monitor U3 in both the horizontal direction and the vertical direction, the image enlarging unit U1 will be described first.

  FIG. 13 shows a configuration example of the image enlarging means U1. The illustrated image enlargement means U1 includes a horizontal direction zero insertion means U1A, a horizontal direction low frequency component passage means U1B, a vertical direction zero insertion means U1C, and a vertical direction low frequency component passage means U1D. The horizontal zero insertion means U1A generates an image DU1A in which pixels having a pixel value of 0 in the horizontal direction of the original image DORG are appropriately inserted. The horizontal direction low frequency component passing means U1B generates an image DU1B in which only the low frequency component of the image DU1A is extracted by low pass filter processing. The vertical zero insertion unit U1C generates an image DU1C in which pixels having a pixel value of 0 in the vertical direction of the image DU1B are appropriately inserted. The vertical low frequency component passing means U1D generates an image DU1D obtained by extracting only the low frequency component of the image DU1C by low-pass filter processing. The image DU1D is output from the image enlargement unit U1 as an image DU1 obtained by doubling the original image DORG in both the horizontal and vertical directions.

  14A to 14E are diagrams for explaining the operation of the image enlarging means U1 in detail. FIG. 14A shows the original image DORG, FIG. 14B shows the image DU1A, and FIG. ) Represents the image DU1B, FIG. 14D represents the image DU1C, and FIG. 14E represents the image DU1D. 14A to 14E, a square (each square) represents a pixel, and a symbol or a numerical value written therein represents a pixel value of each pixel.

  The horizontal direction zero insertion means U1A inserts one pixel with a pixel value of 0 for each pixel in the horizontal direction into the original image DORG shown in FIG. 14A (that is, adjacent to the original image DORG in the horizontal direction). An image DU1A shown in FIG. 14B is generated by inserting one pixel row composed of pixels having a pixel value of 0 between the pixel rows. The horizontal direction low frequency component passing means U1B performs a low-pass filter process on the image DU1A shown in FIG. 14B to generate an image DU1B shown in FIG. The vertical zero insertion means U1C inserts one pixel having a pixel value of 0 for each pixel in the vertical direction into the image DU1B shown in FIG. 14C (that is, adjacent to the image DU1B in the vertical direction). An image DU1C shown in FIG. 14D is generated by inserting one pixel row composed of pixels having a pixel value of 0 between the pixel rows. The vertical low frequency component passing means U1D performs a low pass filter process on the image DU1C shown in FIG. 14D to generate an image DU1D shown in FIG. With the above processing, an image DU1D in which the original image DORG is doubled in both the horizontal direction and the vertical direction is generated.

  FIGS. 15A to 15D show the processing effect of the image enlarging means U1 on the frequency space, FIG. 15A shows the frequency spectrum of the original image DORG, and FIG. 15B shows the image DU1A. FIG. 15C shows the frequency response of the horizontal low frequency component passing means U1B, and FIG. 15D shows the frequency spectrum of the image DU1B. 15A to 15D, the horizontal axis is the frequency axis representing the spatial frequency in the horizontal direction, and the vertical axis represents the frequency spectrum or the intensity of the frequency response. Note that the number of pixels of the original image DORG is half that of the input image DIN. In other words, the sampling interval of the original image DORG is twice the sampling interval of the input image DIN. Therefore, the Nyquist frequency of the original image DORG is half of the Nyquist frequency of the input image DIN, that is, Fn / 2.

  In FIGS. 15A to 15D, only one frequency axis is used to simplify the notation. However, normally, image data consists of pixel values given on a pixel array arranged in a two-dimensional plane, and its frequency spectrum is also given on a plane stretched by a horizontal frequency axis and a vertical frequency axis. It is. Therefore, in order to accurately represent the frequency spectrum of the original picture DORG or the like, it is necessary to describe both the horizontal frequency axis and the vertical frequency axis. However, the shape of the frequency spectrum usually spreads isotropically around the origin on the frequency axis, and as long as the frequency spectrum in the space spanned by one frequency axis is shown, the frequency axis It is easy for those skilled in the art to expand and consider the space spanned by two. Therefore, unless otherwise specified in the following description, the description on the frequency space is performed using a space stretched by one frequency axis.

  First, the frequency spectrum of the original picture DORG will be described. Normally, a natural image is input as the original image DORG, but its spectral intensity is concentrated around the origin of the frequency space. Therefore, the frequency spectrum of the original picture DORG is a spectrum SPO represented as shown in FIG.

  Next, the spectral intensity of the image DU1A will be described. The image DU1A is generated by inserting one pixel per pixel and a pixel value of 0 in the horizontal direction with respect to the original image DORG. When such processing is performed, aliasing around the Nyquist frequency of the original picture DORG occurs in the frequency spectrum. That is, since a spectrum SPM in which the spectrum SPO is folded around the frequency ± Fn / 2 is generated, the frequency spectrum of the image DU1A is expressed as shown in FIG.

  Next, the frequency response of the horizontal low frequency component passing means U1B will be described. Since the horizontal low frequency component passing means U1B is realized by a low pass filter, its frequency response becomes lower as the frequency becomes higher as shown in FIG.

  Finally, the frequency spectrum of the image DU1B will be described. An image DU1B is obtained by performing low-pass filter processing having the frequency response shown in FIG. 15C on the image DU1A having the frequency spectrum shown in FIG. Therefore, as shown in the image DU1B, the frequency spectrum of the image DU1B includes a spectrum SP2 in which the intensity of the spectrum SPM has dropped to some extent and a spectrum SP1 in which the intensity of the spectrum SPO has dropped to some extent. In general, the frequency response of the low-pass filter decreases as the frequency increases. Therefore, when the intensity of the spectrum SP1 is compared with the spectrum SPO, the spectrum intensity on the high frequency component side, that is, the frequency near ± Fn / 2 is reduced by the horizontal low frequency component passing means U1B.

  Of the processing by the image enlarging means U1, the description of the operation on the frequency space of the processing by the vertical zero insertion means U1C and the vertical low frequency component passing means U1D is omitted, but from the contents of the processing. It can be easily understood that there is an action similar to that described with reference to FIGS. 15A to 15D with respect to the axial direction representing the spatial frequency in the vertical direction. That is, the frequency spectrum of the image DU1D is obtained by spreading the frequency spectrum shown in FIG. 15D two-dimensionally.

  In the following description, the spectrum SP2 is referred to as a folded component. This aliasing component appears as noise or a false signal having a relatively high frequency component on the image. Such noise or false signals include overshoot, jaggy or ringing.

The operation and effect of the image processing apparatus according to the present invention will be described below.
FIGS. 16A to 16E show the operation when the intermediate image D1 is generated from the input image DIN when the image DU1D obtained by enlarging the original image DORG is input as the input image DIN (or image DU1). FIG. 16A schematically shows the effect, FIG. 16A shows the frequency spectrum of the input image DIN, FIG. 16B shows the frequency response of the high-frequency component image generating means 1A, and FIG. FIG. 16D shows the frequency response of the low frequency component image generation means 1B, FIG. 16D shows the frequency response of the intermediate image generation means 1, and FIG. 16E shows the frequency spectrum of the intermediate image D1. In FIGS. 16A to 16E, only one frequency axis is used for the same reason as in FIGS. 15A to 15D.

  Further, in FIGS. 16A to 16E, the intensity of the frequency spectrum or the frequency response is shown only in the range where the spatial frequency is 0 or more, but the frequency spectrum or the frequency response in the following description is on the frequency axis. It becomes a symmetric shape around the origin. Therefore, the figure used for description is sufficient to show only the range where the spatial frequency is 0 or more.

  First, the frequency spectrum of the input image DIN will be described. Since the image DU1D is input as the input image DIN, the frequency spectrum of the input image DIN has the same shape as that illustrated in FIG. 15D as shown in FIG. 16A, and the spectrum of the original image DORG It consists of a spectrum SP1 in which the intensity of SPO has dropped to some extent and a spectrum SP2 that is a folded component.

  Next, the frequency response of the high frequency component image generating unit 1A will be described. Since the high frequency component image generating means 1A is composed of a high-pass filter, the frequency response becomes lower as the frequency becomes lower as shown in FIG.

  Next, the frequency response of the low frequency component image generation means 1B will be described. Since the low frequency component image generating means 1B is composed of a low-pass filter, the frequency response thereof becomes lower as the frequency becomes higher as shown in FIG.

Next, the frequency response of the intermediate image generating unit 1 will be described. Among the frequency components of the input image DIN, the frequency components in the low frequency component side region RL1 shown in FIG. 16D are weakened by the high frequency component image generating unit 1A in the intermediate image generating unit 1. On the other hand, the frequency component in the region RH1 on the high frequency component side shown in FIG. 16D is weakened by the low frequency component image generating unit 1B in the intermediate image generating unit 1. Therefore, as shown in FIG. 16D, the frequency response of the intermediate image generating means 1 has a peak in the intermediate region RM1 whose band is limited by the region RL1 on the low frequency component side and the region RH1 on the high frequency component side. It will have.
This intermediate region RM1 does not include the aliasing component generated when a pixel having a pixel value of 0 is inserted into the original image DORG, and is a part of the region below the Nyquist frequency Fn / 2 of the original image DORG. Occupy.

  Next, the frequency spectrum of the intermediate image D1 will be described. The input image DIN having the frequency spectrum shown in FIG. 16A passes through the intermediate image generating means 1 having the frequency response shown in FIG. 16D, whereby the intermediate image D1 is obtained. The frequency response of the intermediate image generating means 1 has a peak in the intermediate region RM1 band-limited by the region RL1 on the low frequency component side and the region RH1 on the high frequency component side, so the frequency spectrum of the intermediate image D1 is In the frequency spectrum of the input image DIN, the intensity of the portion included in the low frequency component side region RL1 and the high frequency component side region RH1 is weakened. Therefore, the intermediate image D1 is obtained by removing the spectrum SP1 that is the aliasing component from the high frequency component of the input image DIN. That is, the intermediate image generating means 1 has an effect of generating the intermediate image D1 by removing the spectrum SP1 that is the aliasing component from the high frequency component of the input image DIN.

  17 (A) to 17 (C) are views showing the operation and effect of the intermediate image processing means 2, FIG. 17 (A) shows the frequency spectrum of the nonlinear processed image D2A, and FIG. 17 (B) shows the high frequency component. FIG. 17C shows the frequency response of the image generation means 2B, and FIG. 17C shows the frequency spectrum of the image D2B. In FIGS. 17A to 17C, for the same reason as FIGS. 16A to 16E, the intensity of the frequency spectrum or the frequency response is shown only in the range where the spatial frequency is 0 or more.

  As will be described later, the nonlinear processed image D2A includes a high frequency component corresponding to the region RH2 on the high frequency component side. FIG. 17A is a diagram schematically showing the state. The image D2B is generated by passing the nonlinear processed image D2A through the high frequency component image generating means 2B. The high frequency component image generating means 2B is composed of a high-pass filter, and the frequency response becomes higher as the frequency becomes higher as shown in FIG. Therefore, the frequency spectrum of the image D2B is obtained by removing the component corresponding to the region RL2 on the low frequency component side from the frequency spectrum of the nonlinear processed image D2A as shown in FIG. In other words, the nonlinear processing means 2A has an effect of generating a high frequency component corresponding to the region RH2 on the high frequency component side, and the high frequency component image generating means 2B has only the high frequency component generated by the nonlinear processing means 2A. There is an effect to take out.

The above operations and effects will be described in more detail.
FIGS. 18A to 18C and FIGS. 19A to 19C are diagrams showing step edges and signal values of pixels that are continuous when the step edges are sampled.
FIG. 18A shows the step edge and the sampling interval S1, and FIG. 18B shows the signal obtained when the step edge is sampled at the sampling interval S1, and FIG. 18 (B) represents a high-frequency component (a component obtained by subtracting an average value of pixel values in the vicinity of each pixel from each pixel value). On the other hand, FIG. 19A shows a step edge and a sampling interval S2 wider than the sampling interval S1, and FIG. 19B shows a signal obtained when the step edge is sampled at the sampling interval S2. FIG. 19C shows high frequency components of the signal shown in FIG. In the following description, it is assumed that the length of the sampling interval S2 is twice the length of the sampling interval S1.

  As shown in FIG. 18C and FIG. 19C, the center of the step edge appears as a zero cross point Z in the signal representing the high frequency component. In addition, the slope of the signal representing the high frequency component near the zero cross point Z becomes steeper as the sampling interval is short, and the position of the point giving the local maximum and minimum values near the zero cross point Z is also The shorter the sampling interval, the closer to the zero cross point Z.

  That is, even if the sampling interval changes, the position of the zero-cross point of the signal representing the high frequency component does not change near the edge, but the slope of the high frequency component near the edge decreases as the sampling interval decreases (or the resolution increases). The position of the point that gives the local maximum and minimum values approaches the zero-cross point.

  20A to 20F show the intermediate image generation means 1 and the intermediate when the signal obtained by sampling the step edge at the sampling interval S2 is doubled and then input to the image processing apparatus according to the present invention. The operation of the image processing means 2 is shown. As described above, since the internal processing of the intermediate image generation unit 1 and the intermediate image processing unit 2 is performed in each of the horizontal direction and the vertical direction, the processing is performed one-dimensionally. Accordingly, in FIGS. 20A to 20F, the contents of the processing are represented using a one-dimensional signal.

  FIG. 20A shows a signal obtained by sampling the step edge at the sampling interval S2, similarly to FIG. 19B. FIG. 20B is a signal obtained by enlarging the signal shown in FIG. That is, when the original image DORG includes an edge as shown in FIG. 20A, a signal as shown in FIG. 20B is input as the input image DIN. Note that when the signal is doubled, the sampling interval becomes half that before the expansion, so the sampling interval of the signal shown in FIG. 20B is the same as the sampling interval S1 in FIGS. Become. In FIG. 20A, the position represented by the coordinate P3 is the boundary portion on the low luminance side of the edge signal, and the position represented by the coordinate P4 is the boundary portion on the high luminance side of the edge signal.

  FIG. 20C shows a signal representing the high frequency component of the signal shown in FIG. 20B, that is, a signal corresponding to the image D1A output from the high frequency component image generating means 1A. Note that the image D1A is obtained by extracting the high-frequency component of the input image DIN, and therefore includes an aliasing component.

  FIG. 20D shows a signal representing the low frequency component of the signal shown in FIG. 20C, that is, a signal corresponding to the image D1B output from the low frequency component image generating means 1B. Since the image D1B is output as the intermediate image D1 as described above, FIG. 20D corresponds to the intermediate image D1. As shown in FIG. 20D, the local minimum value in the vicinity of the zero cross point Z in the intermediate image D1 appears at the coordinate P3, and the local maximum value appears at the coordinate P4. The situation is shown in FIG. The step edge coincides with the high frequency component extracted from the signal sampled at the sampling interval S2. Further, the aliasing component included in the image D1A is removed by a low-pass filter process performed by the low-frequency component image generation unit 1B.

  FIG. 20E shows an output signal when the signal shown in FIG. 20D is input to the nonlinear processing means 2A, that is, an image output from the nonlinear processing means 2A when the intermediate image D1 is input. D2A is represented. In the nonlinear processing means 2A, the signal values of the coordinates P1 and P2 before and after the zero cross point Z are amplified. Therefore, as shown in FIG. 20E, in the image D2A, the magnitude of the signal value at the coordinates P1 and P2 is larger than the other values, and the position where the local minimum value appears near the zero cross point Z is the coordinate. The position where the local maximum value appears at the coordinate P1 closer to the zero cross point Z from P3 changes from the coordinate P4 to the coordinate P1 closer to the zero cross point Z. This means that the high frequency component is generated by the nonlinear processing in the nonlinear processing means 2A that amplifies the values of the pixels before and after the zero cross point Z. In this way, it is possible to generate a high-frequency component by adaptively changing the amplification factor for each pixel, or appropriately changing the content of processing according to the pixel. That is, the nonlinear processing means 2A has an effect of generating a high frequency component not included in the intermediate image D1, that is, a high frequency component corresponding to the region RH2 on the high frequency component side shown in FIG. is there.

  FIG. 20F shows a signal representing the high frequency component of the signal shown in FIG. 20E, that is, a signal corresponding to the image D2B output from the high frequency component image generating means 2B. As shown in FIG. 20 (F), the local minimum value in the vicinity of the zero cross point Z in the image D2B appears at the coordinate P1, and the maximum value appears at the coordinate P2, and this state shows the step edge shown in FIG. 18 (C). This coincides with the high frequency component extracted from the signal sampled at the sampling interval S1. This means that the high frequency component generated in the nonlinear processing means 2A is taken out by the high frequency component image generating means 2B and output as an image D2B. Further, it can be said that the extracted image D2B is a signal including a frequency component corresponding to the sampling interval S1. In other words, the high frequency component image generation means 2B has an effect of extracting only the high frequency component generated by the nonlinear processing means 2A.

  The adding means 2C adds the intermediate image D1 and the image D2B to generate an image D2C. In the present invention, the image D2C is not added to the input image DIN, but the effect obtained when the image D2C is added to the input image DIN will be described first, and then the image D4 is added instead of the image D2C. The effect will be described.

  As described above, the intermediate image D1 is obtained by removing the aliasing component from the high frequency component of the input image DIN, and corresponds to the high frequency component near the Nyquist frequency of the original image DORG as shown in FIG. Yes. As described with reference to FIG. 15D, since the spectral intensity near the Nyquist frequency of the original image DORG is weakened by the enlargement process in the image enlargement means U1, the intermediate image D1 includes a spectral component weakened by the enlargement process. It is. Furthermore, since the aliasing component is removed from the intermediate image D1, a false signal that causes overshoot, jaggy, or ringing is not included. On the other hand, the image D2B is a high frequency component corresponding to a band equal to or higher than the sampling interval S1 or the Nyquist frequency component of the original image DORG.

  Since the image D2C is obtained by adding the intermediate image D1 and the image D2B, the image D2C is added to the input image DIN to compensate for the spectrum intensity weakened by the enlargement process without enhancing the aliasing component. I get out. Furthermore, since a high frequency component in a band equal to or higher than the Nyquist frequency of the original picture DORG can be added, it is possible to enhance the resolution of the image.

  By the way, it is possible to increase the sharpness of the image and improve the image quality by adding the high frequency component generated as described above to the input image DIN. However, depending on the input image, the high frequency component may be excessive. In some cases, the image quality may deteriorate.

The deterioration of image quality due to the addition of high frequency components will be described with reference to FIGS.
FIG. 21A is a diagram illustrating a case where a periodic pattern such as a striped pattern is included in the input image DIN. In particular, a change in luminance at a portion including a pattern such as a vertical stripe is represented along the horizontal direction of the image.
FIG. 21B shows an intermediate image D1 obtained for the input image DIN shown in FIG.
FIG. 21C shows a nonlinear processed image D2A obtained for the intermediate image D1 shown in FIG. The amplitudes of the points indicated by the coordinates P11, P12, P14, P15, P17, P18, P20, P21, P23, P24, P26, and P27 are amplified by nonlinear processing.
FIG. 21D shows an image D2B obtained for the nonlinear processed image D2A shown in FIG.

  FIG. 21E shows an output image DOUT finally obtained. The output image DOUT is an intermediate image D2 obtained by adding the intermediate image D1 shown in FIG. 21B and the image D2B shown in FIG. 21D to the input image DIN shown in FIG. It is obtained by adding. Here, since the interval indicated by coordinates P12 to P14, the interval indicated by coordinates P18 to P20, and the interval indicated by coordinates P24 to P26, both the intermediate image D1 and the image D2B have positive values. The value of the output image DOUT is larger than that of the input image DIN. On the other hand, in the section indicated by coordinates P15 to P17 and the section indicated by coordinates P21 to P23, the intermediate image D1 and the image D2B both take negative values, so the value of the output image DOUT is smaller than the input image DIN. Become. As a result, as shown in FIG. 21E, the periodic pattern included in the input image DIN appears more clearly, and the resolution of the image increases.

  As described with reference to FIGS. 21A to 21E, the periodic pattern included in the input image DIN becomes clearer as the luminance difference between the bright part and the dark part becomes larger. However, as described above, the luminance difference between the dark part and the bright part becomes larger, which may cause a reduction in image quality.

The deterioration in image quality described here is likely to occur when a moving image input as the input image DIN includes a pattern in which a periodic pattern moves.
Consider the case where a moving pattern included in the moving image input as the input image DIN includes a moving pattern using FIG. 22A and FIG.

  22A to 22D show a series of images constituting a moving image including a pattern in which a periodic pattern moves. In particular, a change in luminance at a place where a pattern such as a vertical stripe moves from left to right is shown. It is shown along the horizontal direction of the image. The range from P10 to P20 in FIG. Hereinafter, a case where the input image DIN is input in the order of FIGS. 22 (A), (B), (C), and (D) will be considered.

  22E to 22F show the output image DOUT obtained at this time. In particular, FIG. 22 (E) shows an output image DOUT obtained for the input image DIN shown in FIG. 22 (A), and FIG. 22 (F) is obtained for the input image DIN shown in FIG. 22 (B). FIG. 22G shows the output image DOUT, FIG. 22G shows the output image DOUT obtained for the input image DIN shown in FIG. 22C, and FIG. 22H shows the input image DIN shown in FIG. The output image DOUT obtained with respect to this is shown.

  Although the input image DIN input after FIG. 22D is not illustrated, FIGS. 22A and 22D have substantially the same shape, and continue to FIG. 22A to FIG. Assume that an image having the same pattern as in C) is input. At this time, the output image DOUT obtained after FIG. 22 (H) is not shown, but the output image DOUT having the same pattern as that shown in FIGS. 22 (E) to 22 (G) is obtained.

FIG. 23 is a graph in which the luminance change of the pixel represented by the coordinate P13 in the output image DOUT shown in FIGS. 22E to 22H is plotted along the time axis.
The time for obtaining the output image DOUT shown in FIG. 22E is N, the time for obtaining the output image DOUT shown in FIG. 22F is N + 1, and the output image DOUT shown in FIG. 22G is obtained. The time is represented by N + 2, and the time for obtaining the output image DOUT shown in FIG. 22H is represented by N + 3. As described above, since the output image DOUT repeats the same pattern as that in FIGS. 22E to 22G after the time N + 3, the luminance change of the pixel represented by the coordinate P13 is the same pattern as the time N to N + 2 after the time N + 3. Will be repeated.

Eventually, the luminance of the pixel represented by the coordinate P13 periodically changes between a bright state and a dark state. Here, when the brightness difference between the bright case and the dark case is extremely far away, it is felt that the pixel blinks periodically.
Further, the same thing occurs in the vicinity of the pixel represented by the coordinate P13. Therefore, the part where the periodic pattern has moved appears to blink partially and may be visually uncomfortable.

  Such a phenomenon occurs when the periodic luminance change included in the input image DIN becomes larger by adding the intermediate image D2. In particular, when the pixel value of the intermediate image D2 is a large positive value or a small negative value (a value having a negative sign and a large absolute value), the luminance change included in the input image DIN becomes larger.

Therefore, in particular, when the pixel value of the intermediate image D2 is a large positive value or a small negative value, the pixel value is corrected to reduce the extent to which the luminance change included in the input image DIN becomes large. , The above flashing can be suppressed.
Since the intermediate image D2 is obtained by adding the intermediate image D1 and the image D2B, when the pixel value of the intermediate image D1 or the image D2B is a large positive value or a small negative value, the pixel value of the intermediate image D2 is also large. It is considered to be a positive value or a small negative value.

  Here, when the pixel value of the intermediate image D1 is a large positive value or a small negative value, the absolute value of the pixel value of the intermediate image D1 is a large value.

  Further, when the absolute value of the pixel value of the intermediate image D1 is a large value, the pixel value of the image D2B is highly likely to be a large positive value or a small negative value. This will be described below.

The absolute value of the pixel value of the intermediate image D1 is large when the pixel value of the intermediate image D1 is a large positive value or a small negative value.
First, consider a case where the pixel value of the intermediate image D1 is a large positive value. The image D2B is obtained by performing non-linear processing on the intermediate image D1 by the non-linear processing means 2A and then performing high-pass filter processing on the high-frequency component image generating means 2B. Since the non-linear processing means 2A amplifies the intermediate image D1 only in the vicinity of the zero cross point, basically, if the intermediate image D1 has a large positive value, the image D2A output from the non-linear processing means 2A also has a large positive value. It is thought that.
In addition, the high-pass filter process is equivalent to the process of subtracting the average value of the pixel values in the vicinity of each pixel from each pixel value, so that the output value of the high-pass filter is also a large positive value for a pixel that has a large positive value. It is likely to be a value. Therefore, when the image D2A has a large positive value, there is a high possibility that the image D2B, which is the high-pass filter processing result for the image D2A, also has a large positive value.
In summary, when the pixel value of the intermediate image D1 is a large positive value, the pixel value of the image D2B is highly likely to be a large positive value.

Next, consider a case where the pixel value of the intermediate image D1 has a small negative value. The image D2B is obtained by performing non-linear processing on the intermediate image D1 by the non-linear processing means 2A and then performing high-pass filter processing on the high-frequency component image generating means 2B. Since the non-linear processing means 2A amplifies the intermediate image D1 only in the vicinity of the zero cross point, basically, if the intermediate image D1 has a small negative value, the image D2A output from the non-linear processing means 2A also has a small negative value. It is thought that.
In addition, since the high-pass filter process is equivalent to the process of subtracting the average value of the pixel values in the vicinity of each pixel from each pixel value, the output value of the high-pass filter is also a small negative value for a pixel having a small negative pixel value It is likely to be a value. Therefore, when the image D2A has a small negative value, there is a high possibility that the image D2B that is the result of the high-pass filter processing for the image D2A also has a small negative value.
In summary, when the pixel value of the intermediate image D1 is a small negative value, the pixel value of the image D2B is also likely to be a small negative value.

  As described above, when the absolute value of the pixel value of the intermediate image D1 is a large value, the pixel value of the image D2B is highly likely to be a large positive value or a small negative value.

  Eventually, in the pixel where the absolute value of the pixel value of the intermediate image D1 is a large value, the pixel values of the intermediate image D1 and the image D2B are both large positive values or both small negative values. The pixel value of the intermediate image D2 is likely to be a large positive value or a small negative value, and the luminance change included in the input image DIN is considered to be larger. Therefore, if correction is performed so that the amplitude of the intermediate image D2 is reduced in the vicinity of a pixel in which the absolute value of the pixel value of the intermediate image D1 is large, the degree of increase in luminance included in the input image DIN is reduced, It is possible to reduce the blinking that can occur at the part where the periodic pattern moves, and to prevent visual discomfort.

  In the image processing apparatus according to the present invention, as described above, the correction calculation means 4B performs correction so that the amplitude of the intermediate image D2 is attenuated in a region where the distribution density of pixels having a large absolute value of the pixel value of the intermediate image D1 is high. In addition, the above-described processing is possible.

  As described above, in the image processing apparatus according to the present invention, the extent to which the luminance change included in the input image DIN is increased by the intermediate image D2 can be reduced, and the blinking that may occur in the portion where the periodic pattern has moved can be suppressed. It becomes possible.

  The intermediate image processing means used in the present invention calculates a high frequency component for performing enhancement processing on the input image based on a frequency component near a specific frequency band of the input image. As long as it can be achieved, processes other than those exemplified above may be used.

  Further, in the image processing apparatus according to the present invention, the correction amount D4A is obtained by a method of multiplying the correction intensity D3 by a predetermined coefficient. At this time, the sign of the pixel value of the intermediate image D2 is set to the coefficient to be multiplied by the correction intensity D3. If it is different between the case of negative and the case of negative, it becomes possible to make corrections to different extents when the brightness becomes brighter and when it becomes darker.

  In addition, the threshold value used in the horizontal direction comparison unit 3Ah is set to a different value depending on whether the sign of the pixel value of the image D1h is positive or negative, or the threshold value used in the vertical direction comparison unit 3Av is set to a positive value. The threshold value used in the comparison means 3A is different from that in the case of negative and the case where the sign of the pixel value of the intermediate image D1 is positive and negative. It is possible to add corrections to different degrees.

  In the above example, the intermediate image D1 is composed of the image D1h in which the frequency band is limited in the horizontal direction of the input image DIN and the image D1v in which the frequency band is limited in the vertical direction of the input image DIN, and the images D1h and D1v The processing is performed for each of the above. Therefore, the effects of the present invention can be obtained in both the horizontal direction and the vertical direction of the input image.

In the above example, when the comparison unit 3A compares the absolute value of each pixel of the intermediate image D1 with a predetermined threshold value, the comparison is performed for each of the images D1h and D1v. However, the comparison method is not limited to this. . For example, as shown in FIG. 24, the images D1h and D1v are first added by the adding means 3C, the absolute value of each pixel value of the obtained image is obtained by the absolute value converting means 3D, and the absolute value D3D is obtained by the comparing means 3A. You may compare with a predetermined threshold value. The value of the comparison result D3A obtained at this time is 1 when the absolute value D3D is greater than the threshold value, and is 0 otherwise.
At this time, the comparison result adding means 3B may add the value of the comparison result D3A within a predetermined range centering on each pixel, and output the obtained value as the addition result D3B. D3B may be output as the correction strength D3.
Furthermore, the correction amount determination unit 4A may obtain the correction amount D4A by multiplying the correction strength D3 obtained as described above by a predetermined coefficient.

  As another method, the correction amount D4A is zero when the correction intensity D3 is less than a predetermined magnitude, and the correction amount D4A is predetermined in at least a part of the area where the correction intensity D3 is equal to or greater than the predetermined magnitude, for example, the entire area thereof. You may make it become a value more than the magnitude | size of this, for example, a fixed value.

  In the modification of FIG. 24, if it is not necessary to provide both the horizontal direction comparison means 3Ah and the vertical direction comparison means 3Av in the comparison means 3A as in the correction strength determination means 3 shown in FIG. It is not necessary to provide both the horizontal direction comparison result adding means 3Bh and the vertical direction comparison result adding means 3Bv inside the means 3B. Further, unlike the correction amount determination means 4A shown in FIG. 10, it is not necessary to provide both the horizontal direction correction amount determination means 4Ah and the vertical direction correction amount determination means 4Av. Therefore, in this modification, the circuit scale can be reduced.

  Further, the threshold value used in the comparison unit 3A is set to a different value depending on whether the sign of the image obtained by adding the images D1h and D1v in the addition unit 3C is positive or negative, or the coefficient used in the correction amount determination unit 4A. By changing the sign of the pixel value of the intermediate image D2 between a positive value and a negative value, correction can be made to a different degree depending on whether the luminance is brighter or darker.

In the example of FIGS. 6 and 24, in the comparison result D3A, the absolute value of the pixel value of the intermediate image D1 is 1 when it is larger than a predetermined threshold value, and is 0 when it is not. The example of D3A is not limited to such a binary one, and as shown in FIG. 25A, at least a part of the absolute value of the pixel value of the intermediate image D1 is smaller than a predetermined threshold value THD1a. The value of the comparison result D3A may be continuously changed (from 0 to D3Ab) in at least some of the sections (from THD1a to THD1b). If the comparison result D3A is binary, when the noise in the time direction is superimposed on a location where the absolute value of the pixel value of the intermediate image D1 is about a predetermined threshold value, In rare cases, the corresponding part may or may not be corrected by the correction means 4. In this case, it may be visually unpleasant repeatedly that the brightness of the corresponding part becomes brighter or darker. On the other hand, as shown in FIG. 25 (A), as long as the intensity of the noise superimposed in the time direction does not exceed the interval in which the value of the comparison result D3A continuously changes (the range from THD1a to THD1b), it is always Since the intermediate image D1 is corrected by the correcting unit 4 and the degree of correction is continuously changed, the above-described visual discomfort is less likely to occur. Even if the comparison result D3A is not continuous, the same effect can be obtained by using a multi-step change (three or more values) as shown in FIG.
Further, if the isolated point process represented by the morphological calculation combining the median filter, the contraction process, and the expansion process is performed on the comparison result D3A, the calculation accuracy of the comparison unit 3A can be improved.

  When such a process is performed, the addition result D3B for each pixel of the intermediate image D1 obtained by adding the comparison result D3A by the comparison result addition unit 3B is an area (neighboring area) including each pixel and its surrounding area. The larger the number of pixels having a large absolute value in the region), the larger the value. In the case where the absolute values of the pixel values of the pixels in the neighboring region are weighted and added, the larger the weighted addition value, the larger the value. .

Embodiment 2. FIG.
FIG. 26 shows a configuration of an image processing apparatus according to Embodiment 2 of the present invention. Similarly to the image processing apparatus according to the first embodiment, the image processing apparatus according to the second embodiment can be used as a part of the image display apparatus.

  In FIG. 26, the components denoted by the same reference numerals as those in FIG. 1 perform the same operations as those of the image processing apparatus according to the first embodiment. The image processing apparatus of FIG. 26 is not provided with the correction strength determination means 3 of FIG. 1, but is provided with a correction means 40 instead of the correction means 4 of FIG.

  Hereinafter, the correction means 40 will be described. FIG. 27 shows a configuration example of the correction means 40. The illustrated correction unit 40 includes a dividing unit 40A, a divided data processing unit 40B, and a combining unit 40C. The components of the correcting means 40 operate as follows for each pixel value of the intermediate image D2 to generate a corrected image D4.

  For each pixel of the intermediate image D2, the dividing unit 40A outputs a signal indicating the sign of the pixel value and the result of dividing the absolute value of the pixel value into a plurality of values. In the example shown in the figure, it consists of code data D40A0 representing the code of the pixel value of the intermediate image D2, and three values D (1), D (2), and D (3) obtained by dividing the absolute value of the pixel value. The divided data D40A1 is output.

  Here, division into three values D (1), D (2), and D (3) is performed using, for example, two threshold values TH (1) and TH (2). When the absolute value of the pixel value of the intermediate image D2 is D, the three values D (1), D (2), and D (3) are expressed as follows, for example.

Note that the thresholds TH (1) and TH (2) satisfy TH (1) ≦ TH (2). Furthermore, the threshold values TH (1) and TH (2) may be different values depending on whether the sign of the pixel value of the intermediate image D2 is positive or negative. The result of adding the three values D (1), D (2), and D (3) is equal to D.

  The divided data processing means 40B has three values Y (1) obtained by attenuating at least one of the three values D (1), D (2), and D (3) constituting the divided data D40A1. Divided data D40B composed of Y (2) and Y (3) is output. In the illustrated example, the attenuation means 40B2 and 40B3 output values Y (2) and Y (3) obtained by attenuating the values D (2) and D (3), respectively.

  The values D40B2 and D40B3 are obtained, for example, by multiplying the values D (2) and D (3) by coefficients k (2) and k (3) less than 1. The coefficient to be multiplied here is determined experimentally so as to obtain a desired image, and may be a different value depending on whether the sign D40A0 is positive or negative.

  The combining unit 40C calculates a value obtained by adding the code represented by the code data D40A0 to the result of adding the divided data D40B, that is, the values Y (1), Y (2), and Y (3), for each pixel. A corrected image D4 having the obtained value as a pixel value is output.

  FIGS. 28A and 28B are diagrams for explaining the effect of the correcting means 40. FIG. FIG. 28A shows the intermediate image D2 input to the correcting means 40, and FIG. 28B shows the corrected image D4 obtained at this time. In the illustrated example, both the values D (2) and D3 (3) are attenuated, and the degree of attenuation with respect to the value D (3) is made larger than the degree of attenuation with respect to the value D (2).

As is apparent from the figure, the amplitude of the correcting means 40 is attenuated when the pixel value of the intermediate image D2 is greater than TH (1) and less than -TH (1). In short, the correction means 40 performs correction so that the amplitude is attenuated at a location where the pixel value of the intermediate image D2 takes a large positive value or a small negative value.
Therefore, the correction means 40 can also reduce the extent to which the luminance change included in the input image DIN is increased by the intermediate image D2, and can suppress blinking that may occur in a portion where the periodic pattern has moved. .

  In the image processing apparatus according to the present invention, if the threshold value used in the dividing unit 40A and the coefficient multiplied by the attenuation units 40B2 and 40B3 are made different according to the sign of the pixel value of the intermediate image D2, the brightness becomes brighter and darker. It is possible to apply corrections to different degrees.

  In the above example, both values D (2) and D (3) are attenuated, but only one of them may be attenuated. For example, only the value D (3) is attenuated, and the amplitude can be attenuated when the pixel value of the intermediate image D2 is larger than TH (2) and smaller than -TH (2). Further, only the value D (2) is attenuated, and the pixel value of the intermediate image D2 is greater than TH (1) and less than or equal to TH (2), and less than -TH (1) and greater than or equal to -TH (2). In this case, the amplitude can be attenuated.

と表され、Ｄ（ｎ）は

と表され、上記以外のＤ（ｊ）、すなわちｊが２≦ｊ≦ｎ−１の範囲に含まれる場合は

と表される。ここで閾値ＴＨ（ｊ）はＴＨ（ｊ）≦ＴＨ（ｊ＋１）を満たすものとする。さらに閾値ＴＨ（ｊ）は中間画像Ｄ２の画素値が正の場合と負の場合で異なる値としてもよい。なお、以上のようにして得られたＤ（ｊ）を全て加算するとＤと等しくなる。 Further, in the above example, the absolute value of the pixel value of the intermediate image D2 is divided into three values. However, the number to be divided is not limited to three, and is divided into n values (n is an integer of 2 or more). May be. The method of dividing the absolute value D of the pixel value of the intermediate image D2 into n values D (j) (j = 1 to n) is performed by n−1 threshold values TH (j) (j = 1 to n−1). For example, it is expressed as follows. That is, D (1) is

And D (n) is

And D (j) other than the above, that is, j is included in the range of 2 ≦ j ≦ n−1

It is expressed. Here, the threshold value TH (j) satisfies TH (j) ≦ TH (j + 1). Further, the threshold value TH (j) may be different depending on whether the pixel value of the intermediate image D2 is positive or negative. Note that D (j) obtained as described above is all added to be equal to D.

At this time, the divided data processing means 40B obtains at least one of the values D (2) to D (n) for the divided data D40A1 composed of the n values D (j) obtained as described above. Divided data D40B composed of n values Y (j) obtained by attenuation is output. Attenuation is performed, for example, by multiplying D (j) by a coefficient less than 1. The degree of attenuation is increased, for example, for a larger j.
The synthesizing unit 40C may add the code represented by the code data D40A0 to the value obtained by adding the n values Y (j) constituting the divided data D40B and output it.

  Note that the degree of attenuation may be different depending on whether the sign of the pixel value of the intermediate image D2 is positive or negative. For example, when a predetermined coefficient k (j) is multiplied to attenuate the value D (j), the value of k (j) differs depending on whether the sign of the pixel value of the intermediate image D2 is positive or negative It is good.

Further, in the above example, the value D (1) is not attenuated, but the purpose is as follows.
The purpose of the correction means 40 is to apply correction so that the pixel value of the intermediate image D2 is attenuated at a location where the pixel value of the intermediate image D2 has a large positive value or a small negative value. There is no need to make any corrections in places where the value of or a large negative value is taken. In the above example, since at least the value D (1) is not attenuated, the pixel value becomes a positive value smaller than TH (1) and the case where the pixel value becomes a negative value larger than -TH (1). Does not decay its value. In other words, unnecessary correction is not applied to a portion where the pixel value of the intermediate image D2 takes a small positive value or a large negative value.

  In the above example, the intermediate image D1 is composed of the image D1h in which the frequency band is limited in the horizontal direction of the input image DIN and the image D1v in which the frequency band is limited in the vertical direction of the input image DIN, and the images D1h and D1v The processing is performed for each of the above. Therefore, the effects of the present invention can be obtained in both the horizontal direction and the vertical direction of the input image.

Embodiment 3 FIG.
FIG. 29 shows the configuration of an image processing apparatus according to Embodiment 3 of the present invention. The image processing apparatus according to the third embodiment can also be used as a part of the image display apparatus, like the image processing apparatuses according to the first and second embodiments.

  In FIG. 29, constituent elements denoted by the same reference numerals as those in FIG. 1 perform the same operations as those of the image processing apparatus according to the first embodiment. 29 is not provided with the correction intensity determination unit 3 and the correction unit 4 of FIG. 1, and instead of the intermediate image processing unit 2 and the addition unit 5 of FIG. Means 50 are provided. Hereinafter, the adding means 50 and the intermediate image processing means 20 will be described.

  The adding means 50 adds an intermediate image D2 generated by a method described later to the input image DIN, and outputs the addition result as an output image DOUT.

  FIG. 30 shows a configuration example of the intermediate image processing means 20. In FIG. 30, the constituent elements denoted by the same reference numerals as those in FIG. The intermediate image processing means 20 in FIG. 30 is generally the same as the intermediate image processing means 2 in FIG. 3, but differs in the following points. That is, correction means 2C1 and 2C2 are added, and an addition means 2D is provided instead of the addition means 2C of FIG. Hereinafter, the correcting means 2C1 and 2C2 and the adding means 2D will be described.

The correcting unit 2C1 includes correcting units 2C1h and 2C1v. Each of the correction means 2C1h and 2C1v is configured in the same manner as the correction means 40 described with reference to FIG.
The correcting unit 2C1h performs the same correction on the image D1h as the correction performed on the intermediate image D2 by the correcting unit 40 in the second embodiment. The resulting image is output as an image D2C1h.
The correcting unit 2C1v performs the same correction on the image D1v as the correction performed on the intermediate image D2 by the correcting unit 40 in the second embodiment. Then, an image obtained as a result is output as an image D2C1v.
An image D2C1 composed of images D2C1h and D2C1v is output from the correcting means 2C1.

The correcting unit 2C2 includes correcting units 2C2h and 2C2v. Each of the correction means 2C2h and 2C2v is configured similarly to the correction means 40 described with reference to FIG.
The correcting unit 2C2h performs the same correction on the image D2Bh as the correction performed on the intermediate image D2 by the correcting unit 40 in the second embodiment. The resulting image is output as an image D2C2h.
The correcting unit 2C2v performs the same correction on the image D2Bv as the correction performed on the intermediate image D2 by the correcting unit 40 in the second embodiment. The resulting image is output as an image D2C2v.
An image D2C2 composed of images D2C2h and D2C2v is output from the correcting means 2C2.

The adding means 2D adds the images D2C1 and D2C2.
Here, the image D2C1 is composed of the images D2C1h and D2C1v, and the image D2C2 is composed of the images D2C2h and D2C2v. Therefore, adding the images D2C1 and D2C2 means adding the images D2C1h, D2C1v, D2C2h, and D2C2v. The addition here may be simple addition or weighted addition.

  The correction unit 2C1h can generate an image D2C1h that is corrected so that the amplitude is attenuated at a location where the pixel value of the image D1h takes a large positive value or a small negative value. In the correction unit 2C1v, It is possible to generate an image D2C1v that is corrected so that the amplitude is attenuated at a location where the pixel value of the image D1v takes a large positive value or a small negative value, and the correction means 2C2h can generate a pixel value of the image D2Bh. Can generate an image D2C2h that has been corrected so that the amplitude is attenuated at a place where the value is large and a small negative value. In the correction means 2C2v, the pixel value of the image D2Bv is a large positive value. It is possible to generate an image D2C2v that has been corrected so that the amplitude is attenuated at a place where a small negative value is taken.

  Here, let us consider a case where correction by the correction means 2C1 and 2C2 is not applied. In this case, the intermediate image D2 is obtained by adding the images D1h, D1v, D2Bh, and D2Bv. Therefore, it is considered that the pixel value of the intermediate image D2 is likely to take a large positive value or a small negative value when the pixel values of the images D1h, D1v, D2Bh, D2Bv are large positive values or small negative values. It is done.

  On the other hand, as described above, the correction unit 2C1h generates the image D2C1h that is corrected so that the amplitude is attenuated at a location where the pixel value of the image D1h takes a large positive value or a small negative value. The correction unit 2C1v can generate an image D2C1v that has been corrected so that the amplitude is attenuated at a location where the pixel value of the image D1v takes a large positive value or a small negative value. The means 2C2h can generate an image D2C2h that is corrected so that the amplitude is attenuated at a location where the pixel value of the image D2Bh takes a large positive value or a small negative value. The correction means 2C2v Since it is possible to generate an image D2C2v that is corrected so that the amplitude is attenuated at a place where the pixel value of D2Bv takes a large positive value or a small negative value, The intermediate image D2 obtained by calculation is a positive value where the pixel values of the images D1h, D1v, D2Bh, D2Bv are large positive values or small negative values, that is, the pixel values of the intermediate image D2 are large. In a place where it is easy to take a small negative value, correction is made so that the amplitude is attenuated. Therefore, it is possible to reduce the extent to which the luminance change included in the input image DIN becomes large due to the intermediate image D2, and it is possible to suppress blinking that may occur in a portion where the periodic pattern has moved.

  The modification of the correction unit 40 in the second embodiment can be applied to the correction units 2C1h, 2C1v, 2C2h, and 2C2v, and the effect of the deformation is the same as that described in the second embodiment.

  The effect of the image processing apparatus according to the present invention is maximized by including all of the correction units 2C1h, 2C1v, 2C2h, and 2C2v. I can get it.

  In the above example, the intermediate image D1 is composed of the image D1h in which the frequency band is limited in the horizontal direction of the input image DIN and the image D1v in which the frequency band is limited in the vertical direction of the input image DIN, and the images D1h and D1v The processing is performed for each of the above. Therefore, the effects of the present invention can be obtained in both the horizontal direction and the vertical direction of the input image.

Embodiment 4 FIG.
The overall configuration of the image processing apparatus according to the fourth embodiment is as shown in FIG. 29, and the image processing apparatus according to the fourth embodiment is also a part of the image display apparatus, like the image processing apparatuses according to the first to third embodiments. Can be used as When the image processing apparatus according to the fourth embodiment is compared with the image processing apparatus according to the third embodiment, the configuration and operation of the intermediate image processing means 20 are different. Hereinafter, the intermediate image processing means 20 according to the fourth embodiment will be described.

For example, as shown in FIG. 31, the intermediate image processing means 20 in the fourth embodiment includes a nonlinear processing means 2A, a high frequency component image generating means 2B, an adding means 2E1, a correcting means 2F1, an adding means 2E2, a correcting means 2F2, and Addition means 2G is provided.
In FIG. 31, the constituent elements denoted by the same reference numerals as those in FIG. 3 or FIG. 30 perform the same operations as those of the image processing apparatus according to the second embodiment or the third embodiment. The intermediate image processing means 20 in FIG. 31 is not provided with the correction means 2C1 and 2C2 in FIG. 30, but is provided with addition means 2E1 and 2E2 and correction means 2F1 and 2F2. Hereinafter, addition means 2E1 and 2E2, correction means 2F1 and 2F2, and addition means 2G which are different from those in the first or third embodiment will be described.

  The adding means 2E1 outputs the result of adding the images D1h and D1v as an image D2E1. Here, the addition method may be simple addition or weighted addition.

  The adding means 2E2 outputs the result of adding the images D2Bh and D2Bv as an image D2E2. Here, the addition method may be simple addition or weighted addition.

  Each of the correction means 2F1 and 2F2 is configured in the same manner as the correction means 40 described with reference to FIG.

  The correcting unit 2F1 performs the same correction on the image D2E1 as the correction performed by the correcting unit 40 in the second embodiment on the intermediate image D2. Then, an image obtained as a result is output as an image D2F1.

  The correcting unit 2F2 performs the same correction on the image D2E2 as the correction performed on the intermediate image D2 by the correcting unit 40 in the second embodiment. The resulting image is output as an image D2F2.

  The adding means 2G outputs the result of adding the images D2F1 and D2F2 as an intermediate image D2. Here, the addition method may be simple addition or weighted addition.

  The correction unit 2F1 of the image processing apparatus according to the fourth embodiment generates an image D2F1 that is corrected so that the amplitude is attenuated at a location where the pixel value of the image D2E1 takes a large positive value or a small negative value. The correction unit 2F2 can generate an image D2F2 that is corrected so that the amplitude is attenuated at a location where the pixel value of the image D2E2 takes a large positive value or a small negative value.

  Here, let us consider a case where correction by the correction means 2F1 and 2F2 is not applied. In this case, the intermediate image D2 is obtained by adding the images D2E1 and D2E2. Therefore, it is considered that the pixel value of the intermediate image D2 is likely to take a large positive value or a small negative value at a location where the pixel value of the image D2E1 or the image D2E2 takes a large positive value or a small negative value.

  On the other hand, as described above, in the correction means 2F1, correction is applied to the image D2E1 so that the amplitude is attenuated at a location where the pixel value takes a large positive value or a small negative value. In the means 2F2, the image D2E2 is corrected so that the amplitude is attenuated at a location where the pixel value takes a large positive value or a small negative value, so that an intermediate image D2 obtained by adding them is added. Is corrected so that the amplitude is attenuated at a location where the pixel value is a large positive value or a small negative value. Therefore, it is possible to reduce the extent to which the luminance change included in the input image DIN becomes large due to the intermediate image D2, and it is possible to suppress blinking that may occur in a portion where the periodic pattern has moved.

  The modification of the correction unit 40 in the second embodiment can be applied to the correction units 2F1 and 2F2, and the effect of the deformation is the same as that described in the second embodiment.

  The effect of the image processing apparatus according to the present invention is maximized by providing both of the correcting means 2F1 and 2F2, but the effect can also be obtained by providing at least one of the correcting means 2F1 and 2F2.

  In the above example, the intermediate image D1 is composed of the image D1h in which the frequency band is limited in the horizontal direction of the input image DIN and the image D1v in which the frequency band is limited in the vertical direction of the input image DIN, and the images D1h and D1v The processing is performed for each of the above. Therefore, the effects of the present invention can be obtained in both the horizontal direction and the vertical direction of the input image.

Embodiment 5. FIG.
FIG. 32 shows an image processing method according to the fifth embodiment of the present invention. The illustrated image processing method is realized by an intermediate image generation step ST1, an intermediate image processing step ST2, a correction intensity determination step ST3, a correction step ST4, and an addition step ST5.

Details of each step will be described below.
The intermediate image generation step ST1 includes a high frequency component image generation step ST1A and a low frequency component image generation step ST1B as shown in FIG. 33, for example.

  The high frequency component image generation step ST1A includes a horizontal direction high frequency component image generation step ST1Ah and a vertical direction high frequency component image generation step ST1Av. The low frequency component image generation step ST1B includes a horizontal direction low frequency component image generation step ST1Bh. , And a vertical high-frequency nest component image ST1Bv.

  In the high frequency component image generation step ST1A, the following processing is performed on the input image DIN input in an image input step (not shown). First, in the horizontal high-frequency component image generation step ST1Ah, an image D1Ah obtained by extracting a horizontal high-frequency component from the input image DIN is generated by horizontal high-pass filter processing. In the vertical high-frequency component image generation step ST1Av, an image D1Av obtained by extracting the high-frequency component in the vertical direction from the input image DIN is generated by high-pass filtering in the vertical direction. That is, the high frequency component image generation step ST1A generates an image D1A composed of the image D1Ah and the image D1Av from the input image DIN. This operation is equivalent to the high frequency component image generating means 1A.

  In the low frequency component image generation step ST1B, the following processing is performed on the image D1A. First, in the horizontal direction low frequency component image generation step ST1Bh, an image D1Bh obtained by extracting a horizontal low frequency component from the image D1Ah is generated by a horizontal low-pass filter process. In the vertical direction low frequency component image generation step STBv, an image D1Bv obtained by extracting the low frequency component in the vertical direction from the image D1Av is generated by the low pass filter processing in the vertical direction. That is, the low frequency component image generation step ST1B generates an image D1B composed of the image D1Bh and the image D1Bv from the image D1A. This operation is equivalent to the low frequency component image generation means 1B.

  The operation of the intermediate image generation step ST1 is as described above. In the intermediate image generation step ST1, the image D1Bh is set as the image D1h, the image D1Bv is set as the image D1v, and the first intermediate image D1 composed of the image D1h and the image D1v is output. The above operation is the same as that of the intermediate image generating unit 1.

  For example, as shown in FIG. 34, the intermediate image processing step ST2 includes a non-linear processing step ST2A, a high frequency component image generation step ST2B, and an addition step ST2C.

  The non-linear processing step ST2A includes a horizontal non-linear processing step ST2Ah and a vertical non-linear processing step ST2Av, and the high frequency component image generation step ST2B includes a horizontal high frequency component image generation step ST2Bh and a vertical high frequency component image generation. Step ST2Bv is included.

  The horizontal non-linear processing step ST2Ah includes a zero-cross determination step ST311h and a signal amplification step ST312h, for example, as shown in FIG. 35. The vertical non-linear processing step ST2Av is, for example, as shown in FIG. And signal amplification step ST312v.

In the nonlinear processing step ST2A, the following processing is performed on the first intermediate image D1.
First, in the horizontal non-linear processing step ST2Ah, an image D2Ah is generated from the image D1h by processing according to the flow shown in FIG. The processing in the flow shown in FIG. 35 is as follows. First, in the zero cross determination step ST311h, a change in pixel value in the image D1h is confirmed along the horizontal direction. A location where the pixel value changes from a positive value to a negative value or from a negative value to a positive value is regarded as a zero cross point, and the pixels located on the left and right of the zero cross point are notified to the signal amplification step ST312h. In the signal amplification step ST312h, for the image D1h, the pixel value of the pixel notified to be positioned on the left and right of the zero cross point is amplified, and the image is output as the image D2Ah. That is, in the horizontal non-linear processing step ST2Ah, the image D1h is subjected to the same processing as the horizontal non-linear processing means 2Ah to generate the image D2Ah.

  Next, in the vertical nonlinear processing step ST2Av, an image D2Av is generated from the image D1v by processing according to the flow shown in FIG. The processing in the flow shown in FIG. 36 is as follows. First, in the zero cross determination step ST311v, a change in pixel value in the image D1v is confirmed along the vertical direction. Then, a point where the pixel value changes from a positive value to a negative value or from a negative value to a positive value is regarded as a zero cross point, and the pixels located above and below the zero cross point are notified to the signal amplification step ST312v. In the signal amplification step ST312v, the pixel value of the pixel notified to be positioned above and below the zero cross point is amplified for the image D1v, and the image is output as the image D2Av. That is, in the vertical non-linear processing step ST2Av, the image D1v is subjected to the same processing as the vertical non-linear processing means 2Av to generate the image D2Av.

  The above is the operation of the non-linear processing step ST2A, and the non-linear processing step ST2A generates an image D2A composed of the image D2Ah and the image D2Av. The operation is equivalent to the nonlinear processing means 2A.

Next, in the high frequency component image generation step ST2B, the following processing is performed on the image D2A.
First, in the horizontal direction high frequency component image generation step ST2Bh, an image D2Bh obtained by performing a high-pass filter process in the horizontal direction on the image D2Ah is generated. That is, the horizontal direction high frequency component image generation step ST2Bh performs the same processing as the horizontal direction high frequency component image generation means 2Bh.

  Next, in the vertical direction high-frequency component image generation step ST2Bv, an image D2Bv obtained by performing vertical high-pass filter processing on the image D2Av is generated. That is, the vertical high frequency component image generation step ST2Bv performs the same processing as the vertical high frequency component image generation means 2Bv.

  The above is the operation of the high frequency component image generation step ST2B, and the high frequency component image generation step ST2B generates an image D2B composed of the image D2Bh and the image D2Bv. The operation is the same as that of the high frequency component image generating means 2B.

  In the addition step ST2C, the image D2B and the first intermediate image D1 are added to generate an image D2C. At this time, the addition of the images D2B and D1 may be weighted addition. This operation is equivalent to the adding means 2C.

  The above is the operation of the intermediate image processing step ST2, and the intermediate image processing step ST2 outputs the image D2C as the second intermediate image D2. This operation is equivalent to the intermediate image processing means 2.

  The correction strength determination step ST3 includes a comparison step ST3A and a comparison result addition step ST3B as shown in FIG. 37, for example. The comparison step ST3A includes a horizontal direction comparison step ST3Ah and a vertical direction comparison step ST3Av, and the comparison result addition step ST3B includes a horizontal direction comparison result addition step ST3Bh and a vertical direction comparison result addition step ST3Bv.

  The comparison step ST3A compares the absolute value of the pixel value with a predetermined threshold value for each pixel of the intermediate image D1, and outputs the result as a comparison result D3A. That is, the output value obtained as the comparison result D3A is 1 when the absolute value of the pixel value of the intermediate image D1 is greater than a predetermined threshold value, and is 0 otherwise. Since the intermediate image D1 is composed of the images D1h and D1v, the comparison with the threshold value is performed for each of the images D1h and D1v. That is, the comparison step ST3A includes a horizontal direction comparison step ST3Ah that performs a later-described process on the image D1h, and a vertical direction comparison step ST3Av that performs a later-described process on the image D1v. The comparison result D3A includes the horizontal direction comparison step ST3Ah. The comparison result D3Ah to be output and the comparison result D3Av to be output in the vertical direction comparison step ST3Av. Hereinafter, the operations of the horizontal direction comparison step ST3Ah and the vertical direction comparison step ST3Av will be further described.

  In the horizontal direction comparison step ST3Ah, for each pixel of the image D1h, the absolute value of the pixel value is compared with a predetermined threshold value, and the result is output as a comparison result D3Ah. The output value obtained as the comparison result D3Ah is 1 when the absolute value of the pixel value of the image D1h is greater than a predetermined threshold value, and is 0 otherwise. Here, the threshold value may be different depending on whether the sign of the pixel value of the image D1h is positive or negative.

In the vertical direction comparison step ST3Av, the absolute value of the pixel value is compared with a predetermined threshold value for each pixel of the image D1v, and the result is output as the comparison result D3Av. The output value obtained as the comparison result D3Av is 1 when the absolute value of the pixel value of the image D1v is larger than a predetermined threshold value, and is 0 otherwise. Here, the threshold value may be different depending on whether the sign of the pixel value of the image D1v is positive or negative.
The above is the operation of the comparison step ST3A, and this operation is equivalent to the comparison means 3A.

  The comparison result addition step ST3B adds the output values obtained as the comparison result D3A for a plurality of pixels, and outputs the result as the addition result D3B. In this addition, for each pixel (target pixel), an output value obtained as a comparison result D3A for a plurality of pixels located within a predetermined range centered on the target pixel is added. This addition process is performed for each of the comparison results D3Ah and D3Av. That is, the comparison result addition step ST3B includes a horizontal direction comparison result addition step ST3Bh that performs a later-described process on the comparison result D3Ah and a vertical direction comparison result addition step ST3Bv that performs a later-described process on the comparison result D3Av. Consists of an addition result D3Bh output from the horizontal direction comparison result addition step ST3Bh and an addition result D3Bv output from the vertical direction comparison result addition step ST3Bv.

  In the horizontal direction comparison result addition step ST3Bh, the addition result D3Bh is calculated by the same method as the horizontal direction comparison result addition means 3Bh. That is, for the comparison result D3Ah for each pixel, the pixel values of the pixels existing within a predetermined range centered on that pixel are added, and the result is taken as the addition result D3Bh.

  In the vertical direction comparison result addition step ST3Bv, the addition result D3Bv is calculated in the same manner as the vertical direction comparison result addition means 3Bv. That is, for the comparison result D3Av for each pixel, the pixel values of the pixels existing within a predetermined range centered on that pixel are added, and the result is taken as the addition result D3Bv.

Among the above, the horizontal direction comparison step ST3Ah and the horizontal direction comparison result addition step ST3Bh constitute a horizontal direction correction intensity determination step ST3h for obtaining the horizontal direction addition result D3Bh for each pixel, and the vertical direction comparison step ST3Av and vertical direction comparison The result addition step ST3Bv constitutes a vertical direction correction strength determination step ST3v for obtaining the vertical direction addition result D3Bv for each pixel.
The addition result D3B composed of the horizontal direction addition result D3Bh and the vertical direction addition result D3Bv is output as the correction intensity D3 for each pixel.

  The correction strength determination step ST3 outputs a correction strength D3 including a horizontal direction correction strength D3h corresponding to the addition result D3Bh and a vertical direction correction strength D3v corresponding to the addition result D3Bv. This operation is equivalent to the correction strength determination means 3.

  The correction step ST4 will be described. The illustrated correction step ST4 includes a correction amount determination step ST4A and a correction calculation step ST4B as shown in FIG. 38, for example.

  The correction amount determination step ST4A determines the correction amount D4A. The correction amount D4A is determined in the same manner as the correction amount determination means 4A. For example, as shown in FIG. 39, the correction amount determination step ST4A includes a horizontal direction correction amount determination step ST4Ah, a vertical direction correction amount determination step ST4Av, and an addition step ST4Ap. Details of the operation of the correction amount determination step ST4A will be described below.

  In the horizontal direction correction amount determination step ST4Ah, a horizontal direction correction amount D4Ah is obtained. Here, the horizontal direction correction amount D4Ah is performed in the same manner as the horizontal direction correction amount determination unit 4Ah, and is obtained, for example, by multiplying the horizontal direction correction strength D3h by a predetermined value. Here, the predetermined value multiplied by the correction intensity D3h may be different depending on whether the pixel value of the intermediate image D2 is positive or negative.

  In the vertical direction correction amount determination step ST4Av, a vertical direction correction amount D4Av is obtained. Here, the vertical direction correction amount D4Av is performed in the same manner as the vertical direction correction amount determination unit 4Av, and is obtained, for example, by multiplying the vertical direction correction strength D3v by a predetermined value. Here, the predetermined value to be multiplied by the correction strength D3v may be a different value depending on whether the pixel value of the intermediate image D2 is positive or negative.

In addition step ST4Ap, the horizontal direction correction amount D4Ah and the vertical direction correction amount D4Av are added. The addition result is output as the correction amount D4A from the correction amount determination step STD4A.
The above is the operation of the correction amount determination step ST4A, and this operation is equivalent to the correction amount determination means 4A.

The correction calculation step ST4B corrects the pixel value of the intermediate image D1 based on the correction amount D4A. Here, the correction is performed so that the absolute value of the pixel value of the intermediate image D2 is reduced by the absolute value of the correction amount D4A. That is, the operation of the correction calculation step ST4B is the same as that of the correction calculation means 4B.
The above is the operation of the correction step ST4, and this operation is equivalent to the correction unit 4.

The adding step ST5 will be described.
In the addition step ST5, the input image DIN and the corrected image D4 are added. The addition result in the addition step ST5 is output as an output image DOUT.
The above is the operation of the adding step ST5, and this operation is equivalent to the adding means 5.

  The above is the operation of the image processing method according to the fifth embodiment of the present invention, and the operation is equivalent to that of the image processing apparatus according to the first embodiment. Therefore, the image processing method according to the fifth embodiment of the present invention can achieve the same effect as the image processing apparatus according to the first embodiment. Further, the output image DOUT obtained by the fifth embodiment of the present invention can be displayed on the image display device.

  In the above example, when the absolute value of each pixel of the intermediate image D1 is compared with a predetermined threshold value in the comparison step ST3A, the comparison is performed for each of the images D1h and D1v. However, the comparison method is not limited to this. . For example, as shown in FIG. 40, first, the images D1h and D1v are added (ST3C), the absolute value D3D of each pixel value of the obtained image is obtained (ST3D), and the obtained absolute value D3D is set to a predetermined threshold value. You may compare. The value of the comparison result D3A obtained at this time is 1 when the absolute value D3D is greater than the threshold value, and is 0 otherwise.

The operation of the comparison step ST3A shown in FIG. 40 is equivalent to that of the comparison means 3A shown in FIG.
When the processing by the comparison step ST3A shown in FIG. 40 is performed, the comparison result addition step ST3B may output a value obtained by adding the values of the comparison result D3A within a predetermined range around each pixel as the addition result D3B. The correction strength determination step ST3 may output the addition result D3B as the correction strength D3.
Furthermore, the correction amount determination step ST4A may determine the correction amount D4A by multiplying the correction strength D3 obtained as described above by a predetermined coefficient.

  Here, the threshold value used in the comparison step ST3A is set to a different value depending on whether the sign of the image obtained by adding the images D1h and D1v in the addition step ST3C is positive or negative, or the coefficient used in the correction amount determination step ST4A. By making different values depending on whether the sign of the pixel value of the intermediate image D2 is positive or negative, it is possible to make corrections to different degrees depending on whether the brightness is brighter or darker.

Embodiment 6 FIG.
FIG. 41 shows an image processing method according to the sixth embodiment of the present invention. The illustrated image processing method is realized by an intermediate image generation step ST1, an intermediate image processing step ST2, a correction intensity determination step ST3, a correction step ST40, and an addition step ST5.

  In FIG. 41, steps denoted by the same reference numerals as in FIG. 32 perform the same operations as those in the image processing method according to the fifth embodiment. The image processing method in FIG. 41 is not provided with the correction strength determination step ST3 in FIG. 32, and is provided with a correction step ST40 in place of the correction step ST4 in FIG. Hereinafter, only the correction step ST40 will be described, and description of the other steps will be omitted.

  For example, as shown in FIG. 42, the correction step ST40 of the sixth embodiment includes a division step ST40A, a division data processing step ST40B, and a synthesis step ST40C. The correction step ST40 operates as follows for each pixel value of the intermediate image D2 to generate a corrected image D4.

  The division step ST40A outputs the result of dividing each pixel of the intermediate image D2 by the same method as the dividing unit 40A of the second embodiment. For example, code data D40A0 representing the code of the pixel value of the intermediate image D2 and divided data D40A1 composed of three values D (1), D (2), and D (3) obtained by dividing the absolute value of the pixel value. Output.

  The divided data processing step ST40B includes three values Y (1) obtained by attenuating at least one of the three values D (1), D (2), and D (3) constituting the divided data D40A1. The divided data D40B composed of Y (2) and Y (3), for example, the value Y (1) having the same value as the value D (1), and the values D (2) and D (3) are attenuated means 40B2 and 40B3. The divided data D40B composed of the values Y (2) and Y (3) attenuated by the same method is output.

  The synthesis step ST40C calculates, for each pixel, a value obtained by adding the value represented by the code data D40A0 to the result of adding the values Y (1), Y (2), Y (3) constituting the divided data D40B. Then, a corrected image D4 having the obtained value as a pixel value is output.

  The above is the operation of the correction step ST40, and this operation is equivalent to the correction means 40. As is apparent from the above description, the image processing method according to the sixth embodiment performs the same operation as the image processing apparatus according to the second embodiment, so that the same effect as that of the image processing apparatus according to the second embodiment can be obtained. It is also possible to display the output image obtained by the sixth embodiment of the present invention on the image display device.

  In the above example, the absolute value of the pixel value of the intermediate image D2 is divided into three values in the division step ST40A. However, the number of division is not limited to three, and n (n is an integer of 2 or more). ) May be divided. The method of dividing the absolute value D of the pixel value of the intermediate image D2 into n values D (j) (j = 1 to n) is the same as in the second embodiment. In the divided data processing step, among the n values D (j) obtained as described above, at least one of the values D (2) to D (n) is attenuated. A value Y (j) is generated, and the synthesis step adds the value obtained by adding n values Y (j) to the value obtained by adding the sign of the pixel value of the intermediate image D2 to the corrected image D4. What is necessary is just to output as a pixel value.

Embodiment 7 FIG.
FIG. 43 shows an image processing method according to the seventh embodiment of the present invention. An image obtained by the image processing method of Embodiment 7 can also be displayed on the image display device.

  43, steps denoted by the same reference numerals as those in FIG. 32 perform the same operations as those in the image processing method according to the fifth embodiment. The image processing method of FIG. 43 is not provided with the correction intensity determination step ST3 and the correction step ST4 of FIG. 32, and instead of the intermediate image processing step ST2 and the addition step ST5 of FIG. Step ST50 is provided. Hereinafter, the addition step ST50 and the intermediate image processing step ST20 will be described.

  In addition step ST50, an intermediate image D2 generated by a method described later is added to the input image DIN, and the addition result is output as an output image DOUT.

  For example, as shown in FIG. 44, the intermediate image processing step ST20 includes a non-linear processing step ST2A, a correction step ST2C1, a correction step ST2C2, and an addition step ST2D. In FIG. 44, steps denoted by the same reference numerals as those in FIG. 34 perform the same processing as in the fifth embodiment, and thus description thereof is omitted. Hereinafter, the correction steps ST2C1 and 2C2 and the addition step ST2D will be described.

The correction step ST2C1 includes correction steps ST2C1h and 2C1v. Each of the correction steps ST2C1h and ST2C1v is configured in the same manner as the correction step ST40 described with reference to FIG. 42 regarding the sixth embodiment.
In the correction step ST2C1h, the same correction as the correction performed on the intermediate image D2 in the correction step ST40 in the sixth embodiment is performed on the image D1h. The resulting image is output as an image D2C1h.
In the correction step ST2C1v, the same correction as that performed on the intermediate image D2 by the correction step ST40 in the sixth embodiment is performed on the image D1v. Then, an image obtained as a result is output as an image D2C1v.
From the correction step ST2C1, an image D2C1 including images D2C1h and D2C1v is output.

The correction step ST2C2 includes correction steps ST2C2h and 2C2v. Each of the correction steps ST2C2h and ST2C2v is configured similarly to the correction step ST40 described with reference to FIG. 42 regarding the sixth embodiment.
In the correction step ST2C2h, the same correction as that performed on the intermediate image D2 by the correction step ST40 in the sixth embodiment is performed on the image D2Bh. The resulting image is output as an image D2C2h.
In the correction step ST2C2v, the same correction as that performed on the intermediate image D2 by the correction step ST40 in the sixth embodiment is performed on the image D2Bv. The resulting image is output as an image D2C2v.
From the correction step ST2C2, an image D2C2 composed of images D2C2h and D2C2v is output.

In addition step ST2D, the images D2C1 and D2C2 are added.
Here, the image D2C1 is composed of the images D2C1h and D2C1v, and the image D2C2 is composed of the images D2C2h and D2C2v. Therefore, adding the images D2C1 and D2C2 means adding the images D2C1h, D2C1v, D2C2h, and D2C2v. The addition here may be simple addition or weighted addition.

  This completes the description of the operation of the image processing method according to the seventh embodiment. Since the image processing method according to the seventh embodiment performs the same operation as the image processing apparatus according to the third embodiment, it has the same operations and effects as the image processing apparatus according to the third embodiment.

  The effect of the image processing apparatus according to the present invention is maximized by including all of the correction steps ST2C1h, ST2C1v, ST2C2h, and ST2C2v. Can be obtained.

Embodiment 8 FIG.
The overall configuration of the image processing method according to the eighth embodiment is as shown in FIG. 43, and an image obtained by the image processing method according to the eighth embodiment can also be displayed on the image display device. When the image processing method according to the eighth embodiment is compared with the image processing apparatus according to the seventh embodiment, the configuration and operation of the intermediate image processing step ST20 are different. Hereinafter, the intermediate image processing step ST20 in the eighth embodiment will be described.

For example, as shown in FIG. 45, the intermediate image processing step ST20 in the eighth embodiment includes a nonlinear processing step ST2A, a high-frequency component image generation step ST2B, an addition step ST2E1, a correction step ST2F1, an addition step ST2E2, a correction step ST2F2, and Addition step ST2G is included.
In FIG. 45, steps denoted by the same reference numerals as those in FIG. 34 or 44 perform the same operation as the image processing method according to the fifth or seventh embodiment. The intermediate image processing step ST20 of FIG. 31 is not provided with the correction steps ST2C1 and 2C2 of FIG. 44, but is provided with addition steps ST2E1 and 2E2 and correction steps ST2F1 and 2F2. Hereinafter, addition steps ST2E1 and 2E2, correction steps ST2F1 and 2F2, and addition step ST2G different from those in the fifth embodiment or the seventh embodiment will be described.

  Addition step ST2E1 outputs the result of adding images D1h and D1v as image D2E1. Here, the addition method may be simple addition or weighted addition.

  In addition step ST2E2, the result of adding the images D2Bh and D2Bv is output as an image D2E2. Here, the addition method may be simple addition or weighted addition.

  Each of the correction steps ST2F1 and ST2F2 is configured in the same manner as the correction step ST40 described with reference to FIG. 42 regarding the sixth embodiment.

  In the correction step ST2F1, the same correction as that performed on the intermediate image D2 by the correction step ST40 in the sixth embodiment is performed on the image D2E1. Then, an image obtained as a result is output as an image D2F1.

  In the correction step ST2F2, the same correction as that performed on the intermediate image D2 by the correction step ST40 in the sixth embodiment is performed on the image D2E2. The resulting image is output as an image D2F2.

The addition step ST2G outputs the result of adding the images D2F1 and D2F2 as an intermediate image D2. Here, the addition method may be simple addition or weighted addition.
The above is the configuration and operation of the intermediate image processing step ST20.

  The above is the operation of the image processing method according to the eighth embodiment. The operation of the image processing method according to the eighth embodiment is the same as that of the image processing apparatus according to the fourth embodiment. Therefore, the image processing method according to the eighth embodiment has the same operations and effects as the image processing apparatus according to the fourth embodiment.

  The effect of the image processing method according to the eighth embodiment is maximized by providing both of the correction steps ST2F1 and 2F2, but the effect can also be obtained by providing at least one of the correction steps ST2F1 and 2F2.

    DESCRIPTION OF SYMBOLS 1 Intermediate image generation means, 2 Intermediate image processing means, 3 Correction intensity determination means, 4 Correction means, 5 Addition means, DIN input image, D1 Intermediate image, D2 Intermediate image, D3 Correction intensity, D4 correction image, DOUT output image

Claims (4)

Intermediate image generating means for generating a first intermediate image obtained by extracting a component in the vicinity of a specific frequency band of the input image;
Intermediate image processing means for receiving the first intermediate image and generating a second intermediate image;
Correction means for receiving the second intermediate image as input and outputting a corrected image obtained by correcting the second intermediate image;
First adding means for adding the input image and the corrected image;
The correction means includes
The pixel value of the second intermediate image is converted into code data representing a code of the pixel value and first divided data obtained by dividing the absolute value of the pixel value into n values (n is an integer of 2 or more). A dividing means for dividing;
Divided data processing means for generating second divided data consisting of n values in which at least one value is attenuated among the n values constituting the first divided data;
Combining means for outputting a value obtained by adding a code represented by the code data to a value obtained by adding n values constituting the second divided data;
Have
When the absolute value of the pixel value is D and n−1 thresholds satisfying TH (j) ≦ TH (j + 1) are represented by TH (j) (j = 1 to n−1),
Of the n values D (j) (j = 1 to n) constituting the first divided data,
The first value D (1) is represented by the following equation:

The nth value D (n) is represented by the following equation:

The j-th value D (j) (2 ≦ j ≦ n−1) is expressed by the following equation:

further,
The divided data processing means includes n-1 values from the second value D (2) to the nth value D (n) among the n values D (j) represented by the above formula. among the values, images processor characterized by attenuating at least one. An image display device comprising the image processing device according to claim 1 . An intermediate image generation step of generating a first intermediate image obtained by extracting a component in the vicinity of a specific frequency band of the input image;
An intermediate image processing step that receives the first intermediate image as an input and generates a second intermediate image;
A correction step of receiving the second intermediate image as an input and outputting a corrected image obtained by correcting the second intermediate image;
A first addition step of adding the input image and the corrected image;
The correction step includes
The pixel value of the second intermediate image is converted into code data representing a code of the pixel value and first divided data obtained by dividing the absolute value of the pixel value into n values (n is an integer of 2 or more). A splitting step to split;
A divided data processing step of generating second divided data composed of n values in which at least one value is attenuated among n values constituting the first divided data;
The value obtained by adding the n values constituting the second divided data, possess a combining step of outputting a value obtained by adding a code indicating said code data,
When the absolute value of the pixel value is D and n−1 thresholds satisfying TH (j) ≦ TH (j + 1) are represented by TH (j) (j = 1 to n−1),
Of the n values D (j) (j = 1 to n) constituting the first divided data,
The first value D (1) is represented by the following equation:

The nth value D (n) is represented by the following equation:

The j-th value D (j) (2 ≦ j ≦ n−1) is expressed by the following equation:

further,
The divided data processing step includes n−1 values from the second value D (2) to the nth value D (n) among the n values D (j) represented by the above formula. An image processing method , wherein at least one of the values is attenuated . An image display device for displaying an image processed by the image processing method according to claim 3 .

Images