JP2001245153A - Image processing method and apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image processing method and apparatus allows performing dodge processing having a superior characteristic in a shorter processing time than conventionally, that is capable of prevent dropout of a bright space and a blocked-up of a dark space in a photograph taking with a flashlight or opposite light. SOLUTION: To solve these problems by selecting one or more basic compression (decompression) characteristics out of a plurality of basic characteristics, that are set beforehand and used for compressing image gradation and by compressing or decompressing gradation of image information, using selected one or more basic compression (decompression) characteristics.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the technical field of digital image processing used in digital photographic printers and the like, and in particular, even in flash photography scenes and backlight scenes, bright portions are skipped and dark portions are lost. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing method and apparatus capable of rapidly performing image processing enabling high-quality image reproduction without images.

[0002]

2. Description of the Related Art At present, an image photographed on a photographic film (hereinafter referred to as a film) such as a negative film or a reversal film is printed on a photosensitive material (photographic paper) by projecting an image of the film onto the photosensitive material. Exposure, so-called direct exposure, is the mainstream.

On the other hand, in recent years, a printing apparatus using digital exposure, that is, an image recorded on a film is photoelectrically read, the read image is converted into a digital signal, and then various image processing is performed. 2. Description of the Related Art Digital photo printers have been put to practical use as image data for recording, where a photosensitive material is scanned and exposed with recording light modulated according to the image data to record an image (latent image) and print (finished).

A digital photo printer basically includes a scanner (image reading apparatus) that photoelectrically reads an image recorded on a film by reading light incident on the film and reading the projected light. A predetermined process is performed on the read image data or the image data supplied from the digital camera or the like, and the image data for image recording, that is, an image processing device that is used as an exposure condition, and an image data output from the image processing device. For example, a printer (image recording apparatus) that scans and exposes a photosensitive material by light beam scanning to record a latent image and develops the photosensitive material exposed by the printer to reproduce an image (finished) (A developing device).

According to such a digital photo printer, an image can be processed as image data (image quality adjustment) by processing the image data as digital image data. Therefore, gradation adjustment, color balance adjustment, and color / density adjustment can be performed. By performing a sharpness (sharpening) process or the like, a high-quality print that cannot be obtained by conventional direct exposure can be obtained. Moreover, according to the digital photo printer,
Images taken by a digital camera or the like can also be output as prints. As an example of such image processing, a dodging effect in printing by direct exposure may be given by processing image data.

[0006]

The photographing conditions of a photograph are various. For example, as in the case of flash photography or a backlit scene, the difference in the brightness of an image, that is, the difference from the minimum density to the maximum density of an image photographed on a film. In many cases, the area (the difference between the highest density and the lowest density = the dynamic range of the image density) is very wide. However, photosensitive materials (photographic paper)
Has a narrower reproducible density range than a film. Therefore, using a film image with a wide dynamic range,
When a print is created by exposing (printing) a photosensitive material by a normal method, an image may not be properly reproduced.
For example, when making a print with a film image of a person photographed against backlight, if a person is exposed so as to be a suitable image, a bright portion such as the sky will fly white, and conversely, the sky will be suitable. When exposure is performed to form an image, a person is blackened.

Therefore, in a conventional printing apparatus using surface exposure, when a print is created from a film image having such a wide dynamic range, so-called dodging is performed. Dodging means that a light shielding plate or N
For example, in the case of printing from a negative film using a method such as inserting a D filter, etc., if the image is likely to fly, the light exposure is increased, and conversely, the exposure of the dark area where the image is likely to collapse is increased. This is a technique for obtaining a print in which the entire density area of an image photographed on film is properly reproduced by reducing the amount.

The present applicant has developed an image processing method and an image processing apparatus in a digital photo printer or the like which enable reproduction of an image having the same effect as dodging in such direct exposure by processing image data. It has been previously proposed (see Japanese Patent Application Laid-Open No. 10-13680).

This image processing (hereinafter referred to as dodging processing for convenience) analyzes an image (image data) supplied from a scanner or the like, and, based on the analysis result, calculates the total density photographed on the film. Compress (or decompress) image tones so that areas are properly reproduced on output devices such as printers
Then, the image is compressed (expanded) so that the dynamic range of the image becomes a range corresponding to the output device.

More specifically, a bright portion (low-density portion) without changing the intermediate density portion of the image according to the analysis result of the image.
And the dark part (high density part) is compressed independently, linearly or nonlinearly. For example, in a system in which the image data of a bright portion (a high density portion of a negative film = a low density portion of a reproduced image) in a photographing scene has a large numerical value, a bright portion (large image data) in which an image is likely to fly is represented by image data Smaller,
The dark part of the image that is likely to be crushed compresses the gradation by raising the image data.

Therefore, according to this dodging process, an image of an extremely wide density region photographed on a film can be properly reproduced on a photosensitive material, and an image having a wide dynamic range such as a backlight scene or a flash photograph can be obtained. Even in this case, it is possible to output a print in which a high-quality image is reproduced, in which an important subject such as a person's face is properly reproduced by greatly reducing the jump of a bright portion and the collapse of a dark portion.

An object of the present invention is to provide a dodging process having such excellent characteristics in a shorter processing time than in the past, for example, by using the above-described digital photo printer. Another object of the present invention is to provide an image processing method and apparatus capable of suitably improving the productivity of print creation.

[0013]

In order to solve the above-mentioned problems, the present invention sets a plurality of basic compression characteristics or basic expansion characteristics in advance, and sets one or more of the plurality of basic compression characteristics or basic expansion characteristics in advance. Providing an image processing method characterized by selecting a basic compression characteristic or a basic expansion characteristic, and compressing or expanding the gradation of image information using the selected one or more basic compression characteristics or basic expansion characteristics. It is.

Here, the plurality of basic compression characteristics or basic expansion characteristics are preferably set in advance in accordance with at least one of a document type, a document size, and a result of analyzing the image information. Preferably, the one or more basic compression characteristics or the plurality of basic expansion characteristics are selected according to at least one of a document type, a document size, and an analysis result of the image information.

The document types are a negative film, a reversal film and a black and white film, and the document sizes are 135 size, 240 size and 1 size.
Preferably it is a 20/220 size. The above 1
It is preferable that the above-mentioned basic compression characteristics or a plurality of basic expansion characteristics be selected by manual operation. Further, it is preferable that the basic compression characteristic or the basic expansion characteristic is given as a parameter or a look-up table.

The present invention also relates to the above-mentioned image processing method, further comprising a step of analyzing the image information, wherein the one or more selected basic compression characteristics or basic expansion characteristics are used for the image information. The step of compressing or expanding the gradation sets processing conditions for compressing or expanding the gradation of the image information using the selected one or more basic compression characteristics or basic expansion characteristics according to the analysis result. And processing the image information according to set processing conditions. Here, the image analysis is preferably an auto-setup operation.

[0017] The step of compressing or expanding the gradation of the image information using the selected one or more basic compression characteristics or the basic expansion characteristics may be performed manually by the manual operation. Alternatively, it is preferable that a processing condition for compressing or expanding the gradation of the image information is set using a basic expansion characteristic, and the image information is processed according to the set processing condition. Preferably, the processing conditions are set as a look-up table.

Further, according to the present invention, a plurality of basic compression characteristics or a plurality of basic expansion characteristics are set in advance, and one or more basic compression characteristics or one or more basic compression characteristics are calculated from the plurality of basic compression characteristics or the plurality of basic expansion characteristics. While selecting the basic expansion characteristic, the image information is analyzed, and the gradation of the image information is compressed or compressed using one or more selected basic compression characteristics or one or more basic expansion characteristics according to the analysis result. It is an object of the present invention to provide an image processing method characterized by setting processing conditions for expansion and processing the image information according to the set processing conditions.

Further, according to the present invention, a plurality of basic compression characteristics or a plurality of basic expansion characteristics are set in advance, and one or more basic compression characteristics or one or more basic compression characteristics are calculated from the plurality of basic compression characteristics or the plurality of basic expansion characteristics. A basic expansion characteristic is selected, and a processing condition for compressing or expanding the gradation of the image information using one or more selected basic compression characteristics or one or more basic expansion characteristics is set by a manual operation. An image processing method, wherein the image information is processed according to processing conditions.

According to the present invention, at least one of a plurality of preset basic compression characteristics or basic expansion characteristics used for compression or expansion of gradation of image information supplied from an image information supply source is used. Alternatively, there is provided a selecting means for selecting a basic expansion characteristic, and an image processing means for compressing or expanding the gradation of image information using one or more basic compression characteristics or basic expansion characteristics selected by the selection means. Is provided.

According to the present invention, there is provided the image processing apparatus, further comprising: analyzing the image information; and, according to a result of the analysis, a processing condition for compressing or expanding the gradation of the image information. A setting unit configured to set using one or more basic compression characteristics or basic expansion characteristics selected by the image processing unit, wherein the image processing unit processes the image information according to processing conditions set by the setting unit. An image processing apparatus characterized by the following.

The present invention also relates to the above image processing apparatus, further comprising: manually operating a condition for compressing or expanding the gradation of the image information by one or more of the basic conditions selected by the selecting means. An image processing apparatus having a setting unit for setting using a compression characteristic or a basic decompression characteristic, wherein the image processing unit processes the image information according to a processing condition set by the setting unit; Is provided.

[0023] The selecting means may select the one or more of the one or more according to at least one of a document type of an image serving as an image information source, a size of the image serving as an image information source, and an analysis result of the image information. It is preferable to select basic compression characteristics or basic expansion characteristics.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An image processing method and apparatus according to the present invention will be described below in detail with reference to preferred embodiments shown in the accompanying drawings.

FIG. 1 is a block diagram showing one embodiment of a digital photo printer using the image processing method and apparatus of the present invention. A digital photo printer (hereinafter referred to as a photo printer) 10 shown in FIG.
A scanner (image reading device) 12 and an image processing device 14
And a printer 16. Further, the image processing device 14
Is a keyboard 1 for inputting various conditions such as input and setting, selection and instruction of processing, and instruction such as color / density correction.
An operation system 18 having a mouse 8b and a mouse 18b is connected to a display 20 for displaying a simulation image for verification, various operation instructions, and the like.

The scanner 12 is a device that photoelectrically reads an image photographed on the film F or the like one frame at a time. The scanner 12 has a white light source 22, a variable diaphragm 24, a color filter plate 26, and a reading light incident on the film F. Box 28, an imaging lens unit 32,
An image sensor 34 which is an area CCD sensor, an amplifier (amplifier) 36, and an A / D (analog / digital) converter 38 are provided.

In the photo printer 10, the size and form (slides and films, etc.) of a film such as a new photo system (Advanced Photo System) or a 135 (120/220) size negative (or reversal) film or the like are determined. In addition, a dedicated carrier that can be freely attached to the main body of the scanner 12 is prepared, and by changing the carrier, it is possible to cope with various films and processes. Therefore, the size (original size) of the film F to be read (printed) can be detected by the carrier mounted on the scanner 12.
Images (frames) photographed on film and provided for printing are conveyed to a predetermined reading position by this carrier.
Will be retained.

A bar code such as a DX code, an extended DX code, or an FNS code, which has various information such as a film type, is optically recorded on the film F. The film of the new photographic system is formed with a magnetic recording medium in which film information such as an ID number and a film type, and shooting information such as whether or not a flash is used at the time of shooting and the shooting date and time are recorded. The document type can be known from the DX code and each information of the magnetic recording medium. These pieces of information are read by the carrier when reading the image of the film F, and various kinds of information are sent to the image processing device 14.

When reading an image photographed on the film F in such a scanner 12, the reading light emitted from the light source 22 and the light amount of which is adjusted by the variable aperture 24 enters the color filter plate 26 and is adjusted. After being illuminated and diffused by the diffusion box 28, the light is incident on the film F held at a predetermined reading position by the carrier and transmitted therethrough, thereby obtaining projection light carrying an image photographed on the film F. The projection light forms an image on the light receiving surface of the image sensor 34 by the imaging lens unit 32, and the image captured on the film F is photoelectrically read. The output signal of the image sensor 34 is amplified by the amplifier 36, converted into a digital signal by the A / D converter 38, and sent to the image processing device 14.

The color filter plate 26 is composed of R (red), G (green)
And a turret having B (blue) color filters,
Each color filter is inserted into the optical path of the reading light by being rotated by rotating means (not shown). In the illustrated scanner 12, each color filter of the color filter plate 26 is sequentially inserted, and reading is performed three times, whereby the image captured on the film F is separated into three primary colors of R, G, and B. read.

The scanner 12 reads an image photographed on the film F in two scans: a prescan for reading at a low resolution, and a fine scan for obtaining image data corresponding to print output. Do.
At this time, the pre-scan is performed under pre-scan reading conditions set in advance so that the image sensor 34 can read the images of all the films targeted by the scanner 12 without saturation. On the other hand, the fine scan is performed under the fine scan reading conditions set for each frame from the prescan data so that the image sensor 34 is saturated at a density slightly lower than the minimum density of the image (frame). Therefore, the output signals of the prescan and the fine scan are basically the same data except that the resolution and the output level are different.

The image data supply source for supplying image data to the image processing apparatus of the present invention is not limited to such a scanner 12. For example, the illustrated scanner 12 separates an image into three primary colors using a white light source and a color filter plate, but other than this, a light source that emits reading light of the three primary colors using an LED or the like individually. A scanner that reads an image by separating the image into three primary colors by using a scanner may be used. Alternatively, area C
Instead of a CD sensor, a scanner that reads a film image by slit scanning exposure using a three-color line CCD sensor may be used. Further, in addition to a scanner for photoelectrically reading a film, an image reading device for a reflection original, an imaging device for a digital camera, communication means such as a computer communication network, and a recording medium (drive) such as a floppy (registered trademark) disk. Alternatively, image processing may be performed by receiving image data from various image data supply sources.

As described above, the output signal (image data) from the scanner 12 is output to the image processing device 14.
FIG. 2 shows a block diagram of the image processing device 14. As shown in FIG. 2, the image processing device (hereinafter, referred to as a processing device) 14 includes a data processing unit 46, a Log converter 48, a pre-scan (frame) memory 50, a fine scan (frame) memory 52, and a condition setting. It has a unit 54, a pre-scan processing unit 56, and a fine scan processing unit 58.

Although FIG. 2 mainly shows parts related to image processing, the processing device 14 also controls and manages the entire photo printer 10, and other parts than those shown in FIG. , A CPU for controlling the whole, a memory for storing information necessary for the operation of the photo printer 10, and the like.
Further, the operation system 18 and the display 20 are connected to each part via the CPU or the like (CPU bus).

The R, G, and B output data output from the scanner 12 are converted by the data processing unit 46 into DC data.
Predetermined processing such as offset correction, dark time correction, and shading correction is performed. Next, the output data processed by the data processing unit 46 is Log-converted by a Log converter 48 using, for example, an LUT (look-up table), and is converted into digital image (density) data. Is stored in the pre-scan memory 50,
Fine scan (image) data is stored in the fine scan memory 52, respectively.

The condition setting section 54 includes a pre-scan processing section 5
6 (the image processing unit 68) and the fine scan processing unit 58 (the image processing unit 72) for setting image processing conditions of each image (frame). The setup unit 62, the key adjustment unit 64, and the parameter integration Part 66
Having.

The setup section 62 analyzes an image using the prescan data (automatic setup calculation processing).
Is a part for setting image processing conditions for each frame. More specifically, a density histogram of an image is created using pre-scan data, and image characteristics such as LATD (large area transmission density), a predetermined frequency% point of the density histogram such as a minimum density and a maximum density, and an average density are used. Using the density histogram and the image feature amount, fine scan reading conditions, various LUTs and the like in the image processing unit 68 and the image processing unit 72 are calculated by a known method such as a matrix operation or an image processing algorithm. An image processing condition such as a matrix operation expression is calculated.

It should be noted that the setup unit 62 includes a selection unit 62
a. The selection unit 62a includes a memory therein, and stores a plurality of preset basic compression characteristics and a plurality of basic expansion characteristics set in advance. The selection unit 62a selects one or more basic compression characteristics and / or expansion characteristics from at least one of a document type, a document size, and a result of image analysis (auto-up calculation) from among a plurality of basic compression characteristics and basic expansion characteristics stored in the built-in memory. Select the compression (expansion) characteristics. The setup unit 62 sets the conditions of the dodging process using the basic compression (expansion) characteristics selected by the selection unit 62a. That is, the setup section 62 is a main part of the image processing apparatus of the present invention that performs the image processing method of the present invention. This will be described in detail later.

The key adjustment unit 64 includes a density adjustment key, an adjustment key for each of C (cyan), M (magenta), and Y (yellow), a gradation (γ; gamma) adjustment key, which are set on the keyboard 18a. Various adjustment keys such as bright adjustment key, dark adjustment key, sharpness adjustment key, saturation adjustment key,
In accordance with various adjustment instructions and the like input by the mouse 18b, an image adjustment amount is calculated and supplied to the parameter integration unit 66. The parameter integration unit 66 receives the image processing conditions set by the setup unit 62, and converts the image processing conditions into the image processing unit 68 of the prescan processing unit 56 and the image processing unit 7 of the fine scan processing unit 58.
Set to 2. The parameter integration unit 66 further adjusts (corrects) the image processing conditions set in the two processing units, creates correction conditions for performing the adjustment, and performs both adjustments in accordance with the image adjustment amount calculated by the key adjustment unit 64. Make settings for the processing unit.

In the illustrated processing apparatus, basically,
The pre-scan data stored in the pre-scan memory 50 is processed in the pre-scan processing unit 56, and the fine scan data stored in the fine scan memory 52 is processed in the fine scan processing unit 58. The pre-scan processing unit 56 has an image processing unit 68 and a data conversion unit 70. On the other hand, the fine scan processing unit 58 has an image processing unit 72 and a data conversion unit 74.

Image processing section 68 of prescan processing section 56
And the image processing unit 72 of the fine scan processing unit 58, except that the pixel density of the image data to be processed is different.
Basically, it has the same configuration and performs the same processing. Therefore, in the following description, the image processing unit 72 of the fine scan processing unit 58 will be exemplified and described.

The image processing section 72 (68) includes the first LUT 7
6. First matrix computing unit (hereinafter referred to as MTX) 78
And a dodging unit 80. As described above, the image processing conditions in each processing unit are determined by the condition setting unit 54.
Is set by

The first LUT 76 reads out the image data stored in the fine scan memory 52 (pre-scan memory 50) and performs gray balance (color balance) correction, density correction and gradation correction, and performs each correction. LUTs are cascade-connected. The first MTX 78 performs color correction on an image (image data) processed by the first LUT 76. That is, a matrix operation set according to the spectral characteristics of the film F, the spectral characteristics of the photosensitive material (photographic paper), the characteristics of the development processing, and the like is performed so that the image output to the print has an appropriate color. Make corrections.

The dodging processing section 80 is a part for performing digital dodging processing (giving a dodging effect in direct exposure printing by processing digital image data).
MTX 82, low-pass filter (LPF) 84, second LUT 86, and adder 88. When performing the dodging process, the image data processed by the first MTX 78 is sent to the second MTX 82 and the adder 88. On the other hand, when the dodging process is not performed, the first MTX 78
And the data conversion unit 74 (70) are connected by bypass, and the image data is transferred from the first MTX 78 to the data conversion unit 74 (70).
Sent to

The second MTX 82 generates light / dark image data (light / dark image data) of this image from the R, G, and B image data sent from the first MTX 78. There is no particular limitation on the method of generating the light and dark image data.
And taking one third of the average value of the image data of B and
A method of converting color image data into light and dark image data using the YIQ rule is exemplified. For example, the expression “Y = 0.
“3R + 0.59G + 0.11B” exemplifies a method in which only the Y component defined by the YIQ is calculated from the R, G, and B image data to obtain bright and dark image data.

The LPF 84 processes the light and dark image data generated by the second MTX 82 and extracts low-frequency components to two-dimensionally blur the light and dark image to obtain blurred image data of the read image. is there. Note that LP
F84 is used when compressing the gradation of the image, and when expanding the gradation of the image, the second MTX 82 is used.
And the second LUT 86 are bypass-connected, and the light and dark image data generated by the second MTX is sent to the second LUT 86.

As the LPF 84, a FIR (Finite Impulse Respones) generally used for generating blurred image data is used.
Type LPF may be used, but the IIR (I
It is preferable to use an LPF of the (nfinite Impulse Respones) type.

Here, as described above, since the resolution of the image is different between the prescan data and the fine scan data, if the processing is performed using the same LPF, the image reproduced by the display 20 and the printer 16 will be displayed. Will be different. Therefore, it is necessary to change the frequency characteristic of the LPF 84 between the prescan data and the fine scan data according to the resolution. Specifically, the blur amount of blurred image data used for display on the display 20 may be reduced by the resolution ratio. That is, the resolution ratio is m, and the cutoff frequency of the prescan data is fc (p).
And the fine scan data is fc (f),
The LPF may be designed so that “fc (p) ≒ mfc (f)”.

Blurred image data generated by LPF 84 (or light and dark image data generated by second MTX)
Is a gradation compression (expansion) LUT in the second LUT 86.
Is processed.

As described above, the image density area that can be photographed on the film F is generally wider than the density reproduction area in printing. For example, in backlight scenes or flash photography, the density area greatly exceeds the reproduction area of printing. A range of images may be captured.

FIG. 4 shows an example of a density histogram (film density) created by the setup section 62 from the read image data of the negative film. When the reproduction area in printing is the density area indicated by the dotted line, a to c
In the image shown in (1), all the pixels cannot be reproduced in the print, and the high-density portion exceeding the reproduction range (low reading signal intensity = large image data in the illustrated example), that is, the bright portion of the print (shooting scene) On the contrary, the low density portion exceeding the reproduction range, that is, the dark portion of the print is crushed. Therefore, in order to obtain an image in which all the image data is reproduced, it is necessary to compress a region from the highest density to the lowest density of the image (dynamic range of the image density) so as to correspond to the print reproduction area. In other words, by compressing the gradation of the image (image data) so as to provide the same effect as the conventional dodging by direct exposure, the image data is compressed so that the dynamic range is compressed to correspond to the reproduction range of the print. Need to be processed.

On the other hand, when the image on the film F serving as the original is overexposed, the image has a high density as a whole, so that the printed portion tends to be a soft image with a bright portion. On the other hand, in the case of underexposure, the image has a low density as a whole, and therefore, a printed image tends to have a soft tone in dark areas. Therefore, in order to obtain a high-quality image at this time, it is necessary to increase the contrast by increasing the gradation. Specifically, within the reproduction area of the print, the gradation of the high density portion (bright portion on the print) is set in the case of overexposure, and the low density portion (dark portion on the print) is set in the case of underexposure. It is necessary to make a gradation. In other words, when correcting under / over exposure, it is necessary to extend the gradation.

In the illustrated example, the blurred image data (light and dark image data) processed by the gradation compression (expansion) LUT in the second LUT 86 is added to the main image data processed by the first MTX 78, It is assumed that the tone of the main image data is nonlinearly compressed or expanded to correspond to the density reproduction area by printing. As a result, the gradation, density, and dynamic range of the bright and dark parts of the image data to be output are set to be appropriate, and an appropriate print in which a high-quality image is reproduced is obtained even in a flash shooting scene or a backlight scene. It is possible to output stably. That is, gradation compression (expansion) of the second LUT 86
The LUT is an LUT that performs the above-described processing of the blurred image data (bright and dark image data) in order to obtain processing image data that appropriately adjusts the gradation and the like of main image data.

In the illustrated example, as an example, the selection section 62a of the setup section 62 stores three basic compression LUTs having basic compression characteristics as shown in FIGS. 5A to 5C. Have been. 5A to 5C.
In the formula, Yc is the center of the density, for example, the density D is equal to 0.1.
It is about 8.

The basic compression LUT shown in FIG.
This is a compression characteristic emphasizing good reproduction of bright and dark areas. In other words, by compressing the gradation by strongly compressing the density region that greatly exceeds the print reproduction range without compressing the intermediate gradation, the skipping of the bright part and the crushing of the dark part are reduced, and both the density regions are reduced. Reproduction can be suitably performed. FIG.
The basic compression LUT shown in (B) has a compression characteristic of performing overall compression from a bright portion to a dark portion. According to this basic compression LUT, since the gradation is compressed so that the whole becomes close to the intermediate density, the ratio (pass rate) of a proper image can be improved. That is, this basic compression LUT is a basic compression LUT that increases the ratio of prints that can be output (test OK) only by automatic correction by the processing device 14 and improves productivity in lab shops and the like. Basic compressed LU shown in FIG.
T is a compression characteristic in which a bright portion greatly compresses an area that greatly exceeds the print reproduction range, and a dark portion entirely compresses. Alternatively or additionally, FIG.
A basic compression LUT having a compression characteristic opposite to that of (C) may be provided.

For example, the selection unit 62a uses the document type as a parameter, for example, according to whether the film F is a negative film, a reversal film, or a black and white film.
One or more basic compression LUTs are selected. That is, in this example, one or more basic compression characteristics can be defined according to each document type. The document type may be obtained by a bar code such as a DX code read by a scanner carrier, magnetic information of a new photo system, or an input by an operator. In this example, as an example, when the film F is a negative film, the selection unit 62a converts the basic compression LUT shown in FIG.
In the case of a reversal film and a monochrome film, each of the basic compression LUTs shown in FIG. 5A is selected.

As a selection parameter of the basic compression LUT, a document size, for example, 135, 240 or 120/220 size of the film F can be suitably used. That is, in this example, one or more basic compression characteristics can be defined according to the document size. The document size may be obtained by a carrier mounted on the scanner, a bar code such as a DX code read by the carrier of the scanner, magnetic information of the new photo system, or an input by an operator. In this example, when the film F has 135 size and 240 size, for example, the selection unit 62a determines the basic compression LUT shown in FIG. The basic compression LUT shown in FIG.
Select each.

As a selection parameter of the basic compression LUT, a result of image analysis and selection / setting by an operator are also suitable. When using the results of image analysis,
As the analysis result, the ratio between the dark area and the light area on the image of the original scene, the contrast of the image, and the like can be used. For example, in an image where the bright area is dominant,
Since the image may be a backlight scene, FIG.
Is selected so that gradation compression of a portion darker than the intermediate density is positively performed. In the case of an image having a very high contrast, the basic compression characteristics shown in FIG. 5B can be selected so that the gradation is compressed as a whole.

That is, the basic compression L based on the image analysis result
As a method of selecting the UT, for example, using the information of the density histogram, if the ratio of the image light and dark parts is large and the density difference between the light and dark parts is large, the basic compressed LUT shown in FIG. If the ratio of the bright portion of the image is large and the density of the bright portion is very large, the basic compressed LUT shown in FIG. 5C is used. Otherwise, the basic compressed LUT shown in FIG. The basic compression LUT to be used is selected. In addition,
At this time, the analysis result of the image used for selecting the basic compression LUT, for example, the ratio, the density, the density difference, etc. of the bright and dark portions of the image may be appropriately set according to the device characteristics of the photo printer 10 and the like. Good.

The basic compression L shown in FIGS.
The UT corresponds to the compression of the dynamic range of the entire density range from the bright part to the dark part. However, the present invention is not limited to this, and has a plurality of independent basic compression LUTs for the light part and the dark part. The basic compression LUT for the light part and the dark part are selected according to selection parameters such as the document type and document size. May be selected as the basic compression LUTs corresponding to the dynamic range compression of the entire density range.

FIGS. 6A to 6D show an example.
In the example shown in FIGS. 6A to 6D, FIG.
6C and 6C correspond to compression of a light portion, and FIGS. 6B and 6D correspond to compression of a dark portion. Basic compression LUT shown in FIGS. 6 (A) to 6 (D)
Is a basic compression LUT shown in FIGS. 5A and 5B.
Is divided into a bright portion side and a dark portion side with Yc as a boundary. The selection unit 62a of the setup unit 62 includes, for example,
One or more of the document type, document size, image analysis result, and selection / setting by the operator are used as parameters, and one or more of the basic compression LUTs of FIGS. One or more of the basic compression LUTs of FIGS. 6B and 6D for compressing the dark part are selected, and the two are added to create a basic compression LUT corresponding to the compression of the entire density range.

In the image processing apparatus of the present invention, the number of basic compression LUTs to be selected is not limited to one, but may be plural as described above. In this case, for example, the selected basic compression LUTs may be combined or cascaded and used. The parameter used for selecting the basic compression LUT is not limited to one, and the basic characteristic LUT may be selected using a plurality of parameters. Further, the method of selecting the basic compression LUT according to the parameters is not particularly limited.
The selection unit 62a may have the file as a preset file, or the setup unit 62 may appropriately determine the file according to the selection parameter.

The setup unit 62 uses the basic compression LUT selected by the selection unit 62a in this way to automatically set dodging processing conditions according to image analysis (auto setup). The setup unit 62 may, of course, set the basic compression LUT selected by the selection unit 62a as the dodging processing condition. In the present invention, a plurality of basic compression LUTs and basic decompression LUTs (compression or expansion characteristics) are set in advance in this way, for example, according to the document type, document size, image analysis result, selection / setting by an operator, and the like. Then, select a basic compression LUT, etc., and use it to compress (expand) the dodging process
An LUT (condition of dodging process) is set. Thereby, even in a backlight scene or a flash photography scene, a dodging process capable of greatly reducing the jump of a bright portion and the collapse of a dark portion can be performed more quickly than in the past. Print productivity can be improved satisfactorily.

For the sake of convenience, assuming that the compression on the _light side is g _light and the compression on the dark side is g _dark at the boundary of the intermediate density Yc, the basic compression LUT is: “Basic compression LUT = g _light + g _dark "Is indicated. In the illustrated example, the compression ratio f _auto (gradation compression LUT, hereinafter referred to as compression LUT) of the dodging process, which is automatically set by the setup unit 62, is obtained by using the selected basic compression LUT, “f _auto = A × g _light + B × g _dark ”. Here, the coefficients A and B are 0 ≦ A ≦
1, 0 ≦ B ≦ 1, and is appropriately determined according to the state of the image, specifically, the frequency of the light and dark parts, and the image feature amounts such as the maximum density, the minimum density, and the average density of the density histogram. You.

That is, for example, as shown in FIG.
In the case of the image of histogram b,
(Low density) is frequently used, and images such as nighttime flash photography
Can be determined. In the case of such an image, the light side pressure
Large shrinkage, ie g _lightLarge coefficient A
Set it properly. In night flash photography, etc.
The main subject such as an object is on the bright side of the histogram (on the film
High-density side of the image)
However, by performing such processing, the main
The density (brightness) of the subject of interest can be made appropriate.
Conversely, an image of a histogram c indicated by a two-dot chain line in FIG.
In the case of, scenes in snow or backlight
Can be determined. In the case of such an image
Increases the compression ratio on the dark side, that is, g_darkHang on
The coefficient B is set large. In backlit scenes, etc.
The subject of interest is on the dark side of the histogram, creating a dark image.
However, by performing such processing, the main
Brightens the subject to create a high-quality image
You. Also, the maximum density and minimum density of the density histogram
Are significantly out of print gamut,
In order to reproduce the image of
It is necessary to increase the compression ratio.

As a method of determining the coefficients A and B, for example, in the density histogram shown in FIG. 4, the width of the density area deviating from the print reproduction area to the bright side is a, and the density of the density area deviating to the dark side is FIG. 7A shows an LUT showing the relationship between the density area a and the coefficient A which deviate from the bright part side, as shown in FIG. An example is shown in which a LUT indicating the relationship between the density region b deviating on the dark side and the coefficient B as shown in FIG. 7B is prepared, and A and B are determined using the LUT.

Alternatively, as shown in FIG.
An LUT indicating the relationship between the frequency on the dark side (cumulative% = X%) and the coefficient A, and the frequency on the light side (cumulative% = Y%) and the coefficient B as shown in FIG. LUT showing the relationship
9 is prepared from the histogram, and from the print reproduction limit P on the dark side and the print reproduction limit Q on the light side, the cumulative histogram is used. A method of calculating the cumulative percentage of the dark part and the cumulative percentage of the bright part and determining the coefficients A and B using the LUT shown in FIGS. 7A and 7B is also exemplified.

6 (A) to 6 (D) and FIG.
A method of calculating the coefficients A and B from the LUTs shown in (A) and (B) and determining the coefficients A and B by averaging the two, and a method of determining the larger of the two as the coefficients A and B, etc. It is preferably exemplified. Furthermore, the coefficients A and B may be determined by selecting which LUT to use from the histogram.

On the other hand, as described above, when the image of the film F is under / overexposed, to correct this, the gradation of the dark part is set in the case of underexposure, and in the case of overexposure, Raise the gradation of the bright part. That is,
If the image is under / overexposed, the setup unit 62 sets a gradation expansion LUT (hereinafter, referred to as expansion LUT), and expands the image gradation to expand the dynamic range. Note that there is no particular limitation on the method of determining that an image is under / overexposed, and a known method of determining from an image feature amount obtained from a density histogram, an average density, a maximum density, a minimum density, and the like may be used. .

The selection section 62a of the setup section 62 includes:
As an example, the basic expansion LUT shown in FIGS. 10A to 10C is stored. Similar to the compression, the selection unit 62a uses, for example, one or more of the document type, the document size, the image analysis result, and the selection / setting by the operator as parameters as shown in FIGS. 10A to 10C. Select one or more of the basic decompression LUTs.

As an example, in the case of overexposure, FIG.
0 (A), the basic expansion LUT shown in FIG. 10 (B) for underexposure, and FIG. 10 (C) for super underexposure or super overexposure. Are selected respectively. Note that the determination of (super) underexposure or (super) overexposure used for selecting the basic expansion LUT may be appropriately set according to the device characteristics of the photo printer 10 or the like.

Hereinafter, assuming that the expansion of the bright part for mainly correcting the overexposure is q _over and the expansion of the dark part for mainly correcting the underexposure is q _under , the same as the above-described gradation compression. The basic decompression LUT is indicated by “basic decompression LUT = q _over + q _under ”, and the extension rate q _auto (decompression LUT) of the dodging process automatically set by the setup unit 62 is determined by using the selected basic decompression LUT. , “Q _auto = A × q _under + B × q _over ”.

Here, the coefficients A and B are similarly set such that 0 ≦
A ≦ 1, 0 ≦ B ≦ 1, and the state of the image, specifically, the difference between the minimum density of the density histogram and the film base density, the frequency of light and dark areas, the maximum density of the density histogram, It is appropriately determined according to the image feature amount such as the minimum density and the average density. For example, as shown in FIG. 11, a table showing coefficients A and B with respect to the difference between the minimum density (D _min ) of the density histogram and the film base density is created, and the coefficients A and B are used by using this table. An example of a method for determining is shown.

In the image processing apparatus of the present invention, the compression ratio and the expansion ratio by the dodging process are not limited to being automatically set by the setup unit 62, but may be operated by a keyboard operation of the operator (for example, the gradation adjustment key, The compression LUT and the decompression LUT may be created by adding the adjustment by the operator to the compression rate f _auto and the decompression rate q _auto in accordance with the light part adjustment key and the dark part adjustment key). The adjustment of the compression ratio and the expansion ratio by the operator is described in detail in Japanese Patent Application Laid-Open No. 10-13680 by the present applicant. Further, the image processing apparatus of the present invention is not limited to performing both gradation compression and decompression. For example, the image processing apparatus may include only a plurality of basic compression LUTs and perform only gradation compression. Good. Further, if necessary (for example, when a soft focus image is desired), the gradation may be expanded using the blurred image data processed by the LPF 84.

The blurred image data (bright and dark image data) processed by the second LUT 86 is sent to the adder 88. The adder 88 adds the main image data processed by the first MTX 78 and sent directly to the adder 88, and the blurred image data. As a result, the gradation of the main image data is compressed (expanded), and the same effect as that obtained by performing dodging by surface exposure is provided.

More specifically, in the blurred image data processed by the compression LUT in the second LUT 86, the bright part (large image data) is minus and the dark part is plus image data. Therefore, by adding this blurred image data to the main image data processed by the first MTX 78, the bright part of the main image data is small and the dark part is bulky, that is, the dynamic range of the image data is compressed, and The image data is converted into image data corresponding to the output density area. Conversely, the bright and dark image data processed by the decompression LUT has positive light portions and negative dark portions. Therefore, by adding the bright and dark image data to the main image data, the gradation of the image data is obtained. Is stretched.

In this way, a dodging process is performed,
As for the image data whose dynamic range has been compressed (expanded), the pre-scan data is sent to the data conversion unit 70, and the fine scan data is sent to the data conversion unit 74. Note that an image processing unit such as a sharpness processing unit may be arranged between the adder 88 and each conversion unit.
The data conversion unit 70 of the prescan processing unit 56 converts the prescan data processed by the image processing unit 68 into image data corresponding to display on the display 20 using a 3D (three-dimensional) -LUT or the like. It is. On the other hand,
Similarly, the data conversion section 74 of the fine scan processing section 58 converts the fine scan data processed by the image processing section 72 using a 3D-LUT or the like, and converts the data into image data corresponding to image recording by the printer 16. Part.

In the processing device 14, the image data processed by the data conversion unit 70 of the prescan processing unit 56 is displayed on the display 20, while the fine scan processing unit 58 is
The image data processed by the data conversion unit 74 is sent to the printer 16. The display 20 is not particularly limited, and various known display means such as a CRT (Cathode Ray Tube) and a liquid crystal display can be used.

On the other hand, the printer 16 exposes a photosensitive material (photographic paper) according to the image data output from the fine scan processing section 58 to record a latent image, and performs a developing process according to the photosensitive material ( Finish) Output as print.
For example, after the photosensitive material is cut into a predetermined length corresponding to the print, recording of the back print, R exposure, G exposure, and B exposure according to the spectral sensitivity characteristics of the photosensitive material (photographic paper).
The type of light beam is modulated in accordance with image data (recorded image), and is deflected in the main scanning direction to record a latent image by transporting the photosensitive material in a sub-scanning direction orthogonal to the main scanning direction. The photosensitive material on which the latent image has been recorded is subjected to predetermined wet development processing such as color development, bleach-fixing, and washing with water, dried, printed, sorted, and accumulated.

Hereinafter, the present invention will be described in more detail by describing the operation of the photo printer 10.

The operator requested to make a print of the film F loads the carrier corresponding to the film F into the scanner 12, sets the film F at a predetermined position of the carrier, and gives necessary instructions such as a print size to be made. After inputting, the user instructs to start printing. This allows
The aperture value of the variable aperture 24 of the scanner 12 and the accumulation time of the image sensor 34 are set according to the prescan reading conditions, and then the carrier transports the film F, and the frame for printing is transported to the reading position. Is done. Also,
At the time of transporting the film F, barcodes such as DX codes and magnetic information recorded on a magnetic recording medium are read, and necessary information such as a document type and a document size (carrier mounting information is also acceptable) is set up. It is sent to a predetermined site such as the selecting section 62a. Next, the pre-scanning of the frame is started, and the color filters of the color filter plate 26 are sequentially inserted as described above, and the projection light in each is read by the image sensor 34, so that the image of the frame is R, G And B are separated into three primary colors and read photoelectrically.

Pre-scan and fine scan are
The prescan and the fine scan may be performed one frame at a time, or continuously for all frames or for a plurality of predetermined frames. In the following example, in order to simplify the description and clarify the operation, a case where pre-scan and fine scan are performed frame by frame will be described as an example.

The output signal of the image sensor 34 by the pre-scan is amplified by the amplifier 36 and
8 and converted into a digital signal. The digital signal is
The data is sent to the processing unit 14, subjected to predetermined data processing by the data processing unit 46, converted into digital image data by the Log converter 48, and stored in the prescan memory 50.

When the pre-scan data is stored in the pre-scan memory 50, the setup section 62 of the condition setting section 54 reads out the pre-scan data, and prepares a density histogram of the image and calculates image features such as highlights and shadows. Then, the reading conditions of the fine scan of the frame are set and supplied to the scanner 12.

The set-up section 62 further receives the first LU in response to the density histogram, the calculated image feature quantity, or the operator's instruction given as necessary.
LUT in T76, compressed LUT in second LUT
The image processing conditions for the image (frame) in the prescan processing unit 56 and the fine scan processing unit 58 are set, and the image processing conditions are supplied to the parameter integration unit 66. Parameter integration unit 66
The pre-scan processing unit 56
And it is set to a predetermined part of the fine scan processing unit 58. The compression LUT in the second LUT is selected by the selection unit 6
2a selects a basic compression LUT from a plurality of stored basic compression LUTs (or a basic decompression LUT), according to one or more parameters of a document type, a document size, an image analysis result, and an instruction from an operator. The setup unit 62 creates the basic compressed LUT according to the image analysis as described above.

When the image processing conditions are set, the display 20 becomes a verification screen, the prescan processing section 56 reads out the prescan data from the prescan memory 50, and the image processing section 68 displays the image processing conditions corresponding to the image data. , And an image obtained by reproducing the pre-scan data (pre-scan image) is displayed on the display 20 as a simulation image (finished expected image).

Next, the operator performs verification by looking at the simulation image, and, if necessary,
The color, density, gradation, etc. are adjusted using the adjustment key a or the like.
The input of this adjustment is sent to the key adjustment unit 64, which calculates the adjustment amount of the image processing condition according to the adjustment input, and sends it to the parameter integration unit 66. The parameter integration unit 66 corrects the image processing conditions set in the prescan processing unit 56 and the fine scan processing unit 58 according to the sent adjustment amount, and calculates the correction conditions for performing the adjustment to perform both processing. Set at a predetermined position of the unit. Therefore, the image displayed on the display 20 also changes according to the correction, that is, the adjustment input by the operator.

When the operator determines that the image is appropriate (test OK), the operator issues an output instruction. In response, the image processing conditions are determined, and fine scan is started. In addition,
When the test is not performed, the image processing conditions are determined when the image processing conditions are set by the parameter setting unit 66, and the fine scan is started. The fine scan is performed in the same manner as the pre-scan except that the accumulation time of the image sensor 34 and the aperture value of the variable aperture 24 are different, and the output signal from the image sensor 34 is amplified by the amplifier 36, and the A / D converter The digital signal is converted into a digital signal by 38, processed by the data processing section 46 of the processing device 14, converted into fine scan data by the Log converter 48, and sent to the fine scan memory 52. Next, the fine scan data is read from the fine scan memory 52 by the fine scan processing unit 58, image-processed under the image processing conditions determined by the image processing unit 72, further converted by the image data conversion unit 74, and processed by the printer 16. The image data is output as image data corresponding to image recording, output to the printer 16, and printed.

Although the image processing method and apparatus of the present invention have been described in detail with reference to various embodiments, the present invention is not limited to the above-described embodiments, and various modifications may be made without departing from the spirit of the present invention. It goes without saying that improvements and changes may be made.

[0090]

As described in detail above, according to the present invention, in a backlight scene or a flash shooting scene,
The dodging process, which has excellent characteristics that can significantly reduce the jumping of bright areas and the crushing of dark areas, can be performed in a shorter processing time than in the past. Properties can be suitably improved.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment of a digital photo printer using an image processing method and apparatus of the present invention.

FIG. 2 is a block diagram of an embodiment of the image processing apparatus of the digital photo printer shown in FIG.

FIG. 3 is a block diagram of an embodiment of an image processing unit of the image processing apparatus shown in FIG. 2;

FIG. 4 is an example of a density histogram.

FIGS. 5A, 5B, and 5C are diagrams each showing an example of a basic compression LUT.

FIGS. 6A, 6B, 6C and 6D are diagrams each showing another example of a basic compression LUT.

FIGS. 7A and 7B are diagrams illustrating examples of an LUT for determining a coefficient applied to a basic compression LUT.

FIGS. 8A and 8B are diagrams each showing another example of an LUT for determining a coefficient applied to a basic compression LUT.

FIG. 9 is an example of a cumulative histogram of density.

FIGS. 10A, 10B, and 10C are examples of a basic decompression LUT, respectively.

FIG. 11 is a diagram showing an example of an LUT for determining a coefficient for a basic decompression LUT.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 (Digital) photo printer 12 Scanner 14 (Image) processing device 16 Printer 18 Operation system 18a Keyboard 18b Mouse 20 Display 22 Light source 24 Variable aperture 26 Color filter plate 28 Diffusion box 32 Imaging lens unit 34 Image sensor 36 Amplifier 38 A / D converter 46 Data processing unit 48 Log converter 50 Prescan (frame) memory 52 Finescan (frame) memory 54 Condition setting unit 56 Prescan processing unit 58 Finescan processing unit 62 Setup unit 62a Selection unit 64 Key adjustment unit 66 Parameter integration unit 68, 72 Image processing unit 70, 74 Data conversion unit 76 First LUT 78 First MTX 80 Dodging processing unit 82 Second MTX 84 LPF 86 Second LUT 88 Adder

Claims (15)

[Claims] A plurality of basic compression characteristics or basic expansion characteristics are set in advance, and one or more basic compression characteristics or basic expansion characteristics are selected from the plurality of basic compression characteristics or basic expansion characteristics. An image processing method characterized by compressing or expanding the gradation of image information using the above basic compression characteristics or basic expansion characteristics. 2. The image processing method according to claim 1, wherein the plurality of basic compression characteristics or basic expansion characteristics are set in advance according to at least one of a document type, a document size, and an analysis result of the image information. . 3. The method according to claim 1, wherein the one or more basic compression characteristics or the plurality of basic expansion characteristics are selected according to at least one of a document type, a document size, and a result of analyzing the image information. Image processing method. 4. The original type is a negative film, a reversal film or a black and white film, and the original size is 135 size, 240 size and 120/2.
4. The image processing method according to claim 2, wherein the image processing method has a size of 20. 5. The method according to claim 1, wherein the one or more basic compression characteristics or the plurality of basic expansion characteristics are manually selected.
Or the image processing method according to 2. 6. The image processing method according to claim 1, wherein said basic compression characteristic or basic expansion characteristic is given as a parameter or a look-up table. 7. The image processing method according to claim 1, further comprising a step of analyzing the image information, wherein the at least one selected basic compression characteristic or basic expansion characteristic is selected. Compressing or expanding the gradation of the image information by using the one or more selected basic compression characteristics or basic expansion characteristics according to the analysis result. An image processing method, comprising: setting processing conditions for decompression; and processing the image information according to the set processing conditions. 8. The step of compressing or expanding the gradation of the image information by using the one or more selected basic compression characteristics or the basic expansion characteristics is performed by a manual operation. Alternatively, a processing condition for compressing or expanding the gradation of the image information is set using a basic expansion characteristic, and the image information is processed according to the set processing condition. The image processing method described in the above. 9. The image processing method according to claim 7, wherein the processing condition is set as a look-up table. 10. A plurality of basic compression characteristics or a plurality of basic expansion characteristics are set in advance, and one or more basic compression characteristics or one or more basic expansion characteristics are determined from the plurality of basic compression characteristics or the plurality of basic expansion characteristics. At the same time, the image information is analyzed and the selected one is selected according to the analysis result.
A processing condition for compressing or expanding the gradation of the image information is set using the above basic compression characteristics or one or more basic expansion characteristics, and the image information is processed according to the set processing conditions. Image processing method. 11. A plurality of basic compression characteristics or a plurality of basic expansion characteristics are set in advance, and one or more basic compression characteristics or one or more basic expansion characteristics are determined from the plurality of basic compression characteristics or the plurality of basic expansion characteristics. The user selects and manually sets processing conditions for compressing or expanding the gradation of the image information using one or more selected basic compression characteristics or one or more basic expansion characteristics, and according to the set processing conditions. And processing the image information. 12. A method of compressing or expanding gradation of image information supplied from an image information supply source, wherein one or more basic compression characteristics or basic expansion characteristics from a plurality of preset basic compression characteristics or basic expansion characteristics. And an image processing means for compressing or expanding the gradation of image information using one or more basic compression characteristics or basic expansion characteristics selected by the selection means. apparatus. 13. An image processing apparatus according to claim 12, further comprising: analyzing image information; and, according to a result of the analysis, processing conditions for compressing or expanding the gradation of the image information,
A setting unit configured to set using one or more basic compression characteristics or basic expansion characteristics selected by the selection unit, wherein the image processing unit sets the image information in accordance with a processing condition set by the setting unit; An image processing apparatus for performing processing. 14. The image processing apparatus according to claim 12, further comprising: manually setting a processing condition for compressing or expanding the gradation of the image information to one or more of the one or more selected conditions by the selection unit. An image processing apparatus having a setting unit for setting using a basic compression characteristic or a basic decompression characteristic, wherein the image processing unit processes the image information according to processing conditions set by the setting unit; . 15. The image processing apparatus according to claim 1, wherein the selecting unit is configured to determine the one or more of the at least one of: The image processing apparatus according to claim 12, wherein selection of a basic compression characteristic or a basic expansion characteristic is performed.