JP2000036912A - Image processing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image processing method that reproduces image data to be recorded from a character or a line drawing or the like with fidelity independently of an environment or a shape of image and to provide an image processing unit. SOLUTION: An image input section 1 receives image data resulting from reading an image including characters of an original, after a prescribed processing such as color conversion, sharpening, smoothing and inking to the received image data, the resulting image data are printed out by an image output section 8 in a digital color copying machine. A line width control section 6 applies line width control processing such as expansion or reduction of a line width of the received image data and an image area identification section 3 identifies each pixel of the received image data as to whether or not it belongs to a character area to vary a control variable of the line width control section 6 depending on the identification result as to whether or not each pixel belongs to the character area.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to, for example, an image input device such as a color scanner for reading an image including characters on a color original and inputting color image data. Image processing in an image processing apparatus such as a digital color copier that performs predetermined image processing such as line width correction processing and then outputs the image data on paper by image output means such as an electrophotographic color printer. About the method.

[0002]

2. Description of the Related Art In a conventional electrophotographic apparatus, laser light applied to a photosensitive drum does not form an image at one point, and blur occurs. Further, the relationship between the charge potential on the photosensitive drum and the development density is non-linear, and this relationship is easily affected by environmental changes such as temperature and humidity. Therefore, in order to solve the problem that an image faithful to the image data to be recorded is not recorded, for example, the image is recorded thicker than the image data to be recorded, a density correction process is performed.

In this density correction processing, the relationship between the image data to be recorded and the recording density is measured, and the inverse correction is applied to the image data to be recorded based on the measured value to thereby determine the relationship between the image data to be recorded and the recording density. It is to reproduce faithfully.

[0004] However, this method is effective for an image such as a gradation image in which the shading changes continuously, but is not necessarily effective for characters and line drawings. This is because, in the case of a grayscale image, the density can be corrected by increasing or decreasing the image data to be recorded for each pixel, whereas in the case of a line image, the line thickness can be controlled even if only the density is changed. It is difficult to do so.

For this reason, the density of a gradation image is reproduced with some fidelity, but the thickness of characters and line drawings is not faithfully reproduced, and the degree varies depending on the environment and the thickness of characters. There was a problem.

Further, the reproduction of the line depends on the user's request and the type of manuscript, and it is desirable that these can be freely controlled, but this is not possible. As a method for stably recording a line width with an electrophotographic printer, a method of referring to a recording pixel pattern around a target pixel and correcting data of the target pixel if a specific pattern is described in US Pat. No. 4,544,264. It has been disclosed.

However, this method is intended only for characters and line drawings, and when applied to a copying machine in which characters and line images and gradation images are mixedly inputted, there is a problem that the density of the gradation region fluctuates. is there.

[0008]

As described above, according to the conventional recording methods such as the electrophotographic method, especially in the case of images such as characters and line drawings, the image data to be recorded does not exactly match the recorded image. In addition, the degree of the mismatch varies depending on the environment and the like.

Further, when the characters become thicker, an image deterioration such as an increase in copy cost due to an increase in the amount of toner and a crushing of fine and thick characters may occur. However, it was impossible to control them freely.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image processing method capable of faithfully reproducing image data to be recorded, regardless of the environment or the shape of an image, such as characters and line drawings.

[0011]

According to an image processing method of the present invention, an image including characters on a document is read by an image input means, image data is input, and predetermined processing is performed on the input image data. Detecting the line width of the image included in the character area from the input image data, and expanding or reducing the line width of the input image data. The method includes a step of performing a line width control process such as a reduction, and a step of varying a control amount of the line width control process according to a detection result of the line width.

According to the present invention, the line width of the image included in the character area is detected from the input image data, and the control amount of the line width control processing for the input image data is varied according to the detection result. By doing, the character area on the image,
The expansion, reduction, and degree of expansion of image data to be recorded can be controlled according to the line width of characters, the recording characteristics of line segments in the image output unit, and the like, whereby the state of the image data and the image output unit can be controlled. And faithful reproduction of the line width according to.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 schematically shows a configuration of a digital color copying machine as an example of an image processing apparatus to which an image processing method according to the present invention is applied.
The digital color copying machine includes an image input unit 1 such as a color scanner as an image input unit, a color conversion unit 2, an image area identification unit 3 as an identification unit, a filter processing unit 4, an inking unit 5, a line width control. A line width control unit 6, a gradation processing unit 7, an image output unit 8 such as a color printer as an image output unit, a line image pattern generation unit 9 as a test pattern generation unit, and a density measurement as a measurement unit Part 10
It is constituted by such as.

Incidentally, enlargement / reduction processing and various editing processing such as trimming and masking are not directly related to the present invention, and are omitted here. These processes are placed immediately after the image input unit 1, for example.

Hereinafter, the configuration of each unit will be described in detail. First, the image input unit 1 will be described. The image input unit 1 is, for example, a color scanner, optically reads a color image including characters of a document, and outputs color image data 1.
Outputs 1. The color image data 11 represents the R (red), G (green), and B (blue) reflectance of each pixel of the document, and is output as three time-series data obtained by two-dimensionally scanning the information of each pixel. At this time, the number of read pixels per unit length is called a pixel density. In this embodiment, the reading density is 60
0 dpi, that is, a density of 600 pixels per 25.4 mm.

Next, the color conversion section 2 will be described. The color conversion unit 2 outputs color image data 11 representing RGB reflectance.
Is converted into YMC color image data 12 representing the density of the color material to be recorded. The relationship between the RGB reflectance and the YMC density generally has a complicated non-linear relationship. For this reason,
To realize this conversion processing, a three-dimensional table lookup method, a method combining a one-dimensional table lookup and a 3 × 3 matrix, or the like is used. In addition, about a specific structure, for example,
No. 5, JP-B-61-7774, etc., and the description thereof is omitted.

Next, the image area identifying section 3 will be described. The image area identification unit 3 converts the image data 1 output from the color conversion unit 2
2, the character area and the non-character area are separated by referring to the density distribution and density change. The identification signal 1 takes "1" in the character area and "0" in the area other than the character area.
3 is output. Here, the character region is a region including the character and the vicinity outside the edge thereof. For a specific method of image area identification, see, for example,
Since it is described in detail in Japanese Patent Application Laid-Open No. 1995588 and Japanese Patent Application Laid-Open No. Hei 1-3783, the description thereof will be omitted.

Next, the filter section 4 will be described. The filter unit 4 performs a sharpening or smoothing process on the YMC color image data 12 output from the color conversion unit 2.
Generally, in a copying machine, a document image is mainly used as a document in many cases. In such an image, a character image, a gradation image, and the like are mixed. It is important that a character image be reproduced sharply, while a gradation image is important that gradation be reproduced smoothly. Further, printing and commercially available printers often use halftone dots for gradation expression, and it is also important to remove these halftone components.

For this reason, the filter unit 4 selectively switches the filtering process according to the identification signal 13 output from the image area identification unit 3. If the identification signal 13 represents a character, an edge enhancement filter is used to perform edge enhancement processing. When the identification signal 13 represents a grayscale edge, a weak edge emphasis filter is applied. When the identification signal 13 has a gentle gradation, noise and halftone components are removed by applying a smoothing filter. Thereby, the character image can be reproduced sharply, and the gradation image can be reproduced smoothly.

Next, the inking unit 5 will be described. The inking unit 5 converts the YMC color image data 14 filtered by the filter unit 4 into YMCK color image data 1.
Convert to 5. Although black can be expressed by superimposing three color materials of YMC, black color material is generally higher in color density than YMC superimposition and is cheaper in general color recording because it is inexpensive. Recording is performed in four colors of YMCK including materials.

Specifically, for example, systems such as UCR and GCR are known and are actually used. The calculation formula of the GCR method is shown below. However, the input CMY color image data 14 is described as C, M, Y, and the output CMYK color image data 15 is described as C ', M', Y ', K'.

K ′ = k · min (C, M, Y) C ′ = (CK) / (1−K) M ′ = (M−K) / (1−K) Y ′ = (Y− K) / (1-K) Next, the line width control unit 6 will be described. Line width control unit 6
Performs a correction process of the width of the line to be recorded. Here, the identification signal 13 output from the image area identification unit 3 and the recording state signal 1 measured by the density measurement unit 10 described later in detail and stored in the recording state register in the density measurement unit 10
6, the CMYK color image data 15 output from the inking unit 5 is subjected to line width control processing.

A block for detecting the thickness of an input image is provided in the line width control unit 6. The thickness information of the image detected in this block and the input identification signal 1
3 and the recording state signal 16, a line width control amount on the image data is calculated, and the line width is enlarged or reduced according to the calculated control amount. CMYK with line width control
Is sent to the gradation processing unit 7 at the subsequent stage. The line width controller 6 will be described later in more detail.

Next, the gradation processing section 7 will be described. Generally, in recording by electrophotography or the like, an intermediate density is expressed by modulating the length of on / off of light. In the gradation processing unit 7,
This modulation processing is performed. Specifically, a pulse signal having a width corresponding to the image data 17 is generated. On / off of the laser beam is controlled according to the pulse. Here, it is configured to be able to switch between control for moving a pulse forward and control for moving a pulse backward within a unit cycle.

There are two types of modulation, two-pixel modulation and one-pixel modulation. In the two-pixel modulation method, the odd-numbered pixels are recorded in front, and the even-numbered pixels are recorded in back. On the other hand, in the one-pixel modulation method, all the pixels are recorded with the leading edge. In the one-pixel modulation method, since the ON / OFF cycle of the pulse is in units of one pixel, recording can be performed with a resolution of one pixel.

On the other hand, the resolution of the two-pixel modulation method is lower than that of the one-pixel modulation method because the cycle is a unit of two pixels. However, since the pulse width for expressing the same density is doubled, the stability of the density is increased, and the gradation is improved as compared with the one-pixel modulation method. As described above, the one-pixel modulation method is a method suitable for recording a character image, while the two-pixel modulation method is a method suitable for recording a gradation image.

In this embodiment, the identification signal 13
Two-pixel modulation processing and one-pixel modulation processing are selected. Specifically, when the identification signal 13 represents a character, one-pixel modulation processing is selected. When the identification signal 13 represents a gradation edge or a gentle part, two-pixel modulation processing is selected. As a result, in the gradation area, it is possible to reproduce an image with a smooth gradation and rich gradation.
In the character area, a high-resolution and sharp image can be recorded.

Next, the image output unit 8 will be described. The image output unit 8 is, for example, a color printer using an electrophotographic recording method. To briefly explain the principle of the electrophotographic recording method, first, intensity of laser light or the like is modulated according to image data to be recorded, and the modulated light is irradiated onto a photosensitive drum. Electric charges are generated on the photosensitive surface on the photosensitive drum according to the amount of irradiation light. Therefore, by scanning the laser beam in the axial direction of the photosensitive drum according to the scanning position of the image data and rotating and scanning the photosensitive drum, a two-dimensional charge distribution according to the image data is formed on the photosensitive drum. It is formed.

Next, the toner charged by the developing device is caused to adhere to the photosensitive drum. At this time, an amount of toner corresponding to the potential adheres to form an image. Next, the toner on the photosensitive drum is transferred onto a sheet via a transfer belt or the like, and finally, the toner is melted and fixed by a fixing device. By performing this operation sequentially for the four color toners of YMCK, a full-color image can be recorded on paper.

Next, the concentration measuring section 10 will be described.
The density measuring unit 10 measures the density of a line image pattern recorded and output on a sheet. That is, the line image pattern is
In accordance with the line image pattern signal generated by the line image pattern generator 9, the image output unit 8 records and outputs the image on a sheet.

The density measuring unit 9 measures the recording density by irradiating the line image pattern recorded on the paper with light and detecting the reflected light with a light amount sensor or the like. The measured density information is stored as a recording state signal 16 in a recording state register (not shown) in the density measuring section 9 and supplied to the line width control section 6 at the time of image recording.

A line image pattern as a test pattern is composed of lines having a plurality of types of line widths. By using such a pattern, a relationship between image data to be recorded and a line thickness to be recorded is obtained. be able to. In the present embodiment, the content of the recording status register (recording status signal 16) is a 2-bit signal that takes one of 0, 1, 2, and 3. When the recording density of the line is low, the value is small. When the density is high, a large value is taken.

In this embodiment, a value obtained by integrating the reproduction densities of several types of thickness lines is used as the recording state signal. However, a configuration is provided in which each of the thin line and the thick line has a value independently. Is also good.

A series of recording and measuring operations are performed when the copying machine is started. However, the timing is not limited to this. For example, it is performed at regular time intervals or every time before the copying operation. It may be timing. The shorter the interval, the more the influence of the short-term temporal fluctuation of the line width of the recording system can be eliminated.

Next, the configuration and operation of the line width control unit 6 will be described in more detail. FIG. 2 shows the configuration of the line width control unit 6. The line width control unit 6 includes a line width detection unit 21 as a line width detection unit and a line width control amount calculation unit 2 as a line width control amount calculation unit.
2, and a line width expansion / reduction unit 23 as line width expansion / reduction means.

The line width detecting section 21 receives the image data 15 and the identification signal 13 from the inking section 5 and calculates the line width on the image. In the present embodiment, after the image is binarized with an appropriate threshold value, a 7 × 7 pixel reference region centered on the target pixel is taken, and the vertical region of the region where the pixel is “1” is set inside the reference region.
Determine the width in the horizontal and diagonal directions. Then, the minimum value is output as the line width value signal 24. For example, if the binarized image is an image as shown in FIG. 3A, the line width value signal is “4”, and if the image as shown in FIG.
The line width signal is 2 × √2 = 2.8. In the latter case,
The line width value signal is output as "3" by rounding off the decimal part.

In the present embodiment, a signal value "7" is output even when the line width value signal is "7" or more. this is,
This is set in order to reduce the number of bits of the signal, and since it is not necessary to change the processing for lines having a width of 7 pixels or more depending on the line width.

Next, referring to the identification signal 13, if it is "0", that is, if the pixel is determined to be a non-character area, the line width value signal is set to "0". As a result, in the gradation image area, the line width value signal becomes “0”, and it is possible to prevent a linear area or a halftone dot structure on the gradation image from being detected as a line.

In this embodiment, image processing is performed in a pipeline configuration. For this reason, if the sub-scanning size of the reference area is increased, the amount of the line memory for signal delay becomes enormous, and the reference area is set to 7 × 7 pixels. The reference area may be, for example, 5 × 5 pixels or 9 × 9 pixels.
The larger the reference area, the higher the line width resolution of a line with a large line width, but the larger the hardware scale. In practice, it is sufficient to detect a line width of about 5 pixels, so the reference area may be at most about 5 to 7 pixels.

The line width is measured in one direction (main scanning direction).
It may be just. In this case, only the line width of a line parallel to the sub-scanning direction can be correctly detected, so that line width control can be performed only for such a line. it can.

Next, the line width control amount calculation unit 22 outputs a line width control amount signal 25 with reference to the line width value signal 24 and the recording state signal 16 which are the outputs of the line width detection unit 21. The line width control amount signal 25 includes an expansion / reduction selection signal 25a and an expansion / reduction amount signal 25b. The expansion / contraction selection signal 25a is a signal for selecting whether to increase or decrease the line width on the signal. When the signal is “1”, the line width is increased, and when the value is “0”, the line width is decreased. The expansion / contraction amount signal 25b is a signal indicating the degree of increase or decrease in the width. The larger the signal value, the larger the amount of increase or decrease.

In the present embodiment, these signals are generated with reference to a table. The table uses the 2-bit recording state signal 16 and the 3-bit line width value signal 24 as addresses,
It is a 32-entry 4-bit table in which 1 bit of expansion / reduction selection signal and 3 bits of expansion / reduction amount signal are used as data. FIG. 4 shows a configuration example of the table. As shown in FIG. 4, when the recording state signal 16 is large, that is, when the line width tends to be large in the image output unit 8, the expansion / reduction selection signal 2
5a is set to “0” and reduction is selected.
When 6 is small, that is, when the line width tends to be narrow,
The expansion / reduction selection signal 25a is set to “1” to select expansion.

Next, the line width expansion / reduction unit 23 converts the image data 15 according to the line width control amount signal 25 from the line width control amount calculation unit 22 so that the line width expands or contracts. . FIG. 5 shows the configuration of the line width expansion / reduction unit 23. First,
The maximum value filter unit 31 obtains the maximum value of the image signal in the reference area of 3 × 3 pixels centering on the target pixel, and outputs this as the maximum value signal 32. Similarly, the minimum value filter section 33 obtains the minimum value in the reference area, and outputs this as the minimum value signal 34.

Next, the selector 35 outputs the expansion / reduction selection signal 2
Selection of the maximum value signal and the minimum value signal is performed according to 5a.
Here, when the expansion / reduction selection signal 25a is “1”, the maximum value signal 32 is selected, and when the expansion / reduction selection signal 25a is “0”, the minimum value signal 34 is selected.
Output as 6.

Next, the line width modulating section 37 performs an internal division operation represented by the following equation based on the image data (P) 15 and the filter output signal (Q) 36 of the target pixel, which is the central pixel of the reference area, and performs expansion. A reduced output signal (P ') 38 is output.

P '= (1−k) · P + k · Q where k is a coefficient determined from the expansion / contraction amount signal 25b.
Here, for the values of the expansion coefficient signals (K) 0 to 7, k = K
/ 7 value.

Next, the specific meaning of the operation of the line width expansion / reduction unit 23 will be described. The maximum value filter unit 31 is a filter for expanding the image, and expands by an amount corresponding to the size of the reference area of the filter. That is, when the reference area is 3 × 3 pixels as in the present embodiment, expansion is performed by one pixel in both the main scanning direction and the sub-scanning direction. If the input image data is a binary signal, it expands exactly by one pixel, but generally the signal read by the scanner takes an intermediate value due to the influence of the scanner's impulse response characteristics and spatial quantization.
Even in the case of such a signal, an approximately expanded signal can be obtained. For example, when the maximum value filter processing is performed on the image shown in FIG. 6A, the processing result shown in FIG. 6B is obtained.

Similarly, the minimum value signal 34 represents a signal obtained by reducing an image. FIG. 6C shows an example of the processing result of the minimum value filter unit 33 on the input image data shown in FIG. Next, the line width modulation section 37 approximately controls the degree of expansion and contraction by performing internal division processing of these maximum value signals and the signal of the target pixel. That is, when the expansion / reduction amount signal K = 0, the expansion / reduction output signal P ′ = P, and when the expansion / reduction amount signal K = 7, the expansion / reduction output signal P ′ = Q. When the expansion / reduction amount signal K has an intermediate value between them, the expansion / reduction output signal P ′ also has an intermediate value. Therefore, it is possible to approximately control the degree of expansion based on the magnitude of the expansion / reduction amount signal K. it can. This is the same in the case of reduction, and the degree of reduction can be controlled by the expansion / reduction amount signal.

Therefore, by adopting the above configuration, the expansion / reduction selection signal and the expansion / reduction amount signal allow
The expansion, reduction, and degree of expansion and reduction of the image data can be finely controlled. Therefore, by performing recording output in the image output unit 8 according to the image data subjected to these processes, it is possible to freely correct the line width and record.

Further, by controlling the expansion / reduction control amount in accordance with the identification signal, the expansion / reduction processing can be selectively performed only on the character / line width area without affecting the gradation area on the image. it can. Further, by switching the control amount of expansion and contraction in accordance with the line width detection signal, it is possible to perform control in accordance with the line width of the document image. Further, by switching the control amount of expansion and contraction in accordance with the value measured by the density measurement unit, an image having a stable line width can always be recorded and output irrespective of the fluctuation of the recording characteristics of the image output unit.

Next, a first modification of the present invention will be described. In the first modified example, the line width expansion / reduction unit 23 in the line width control unit 6 has substantially the same configuration as that of the above-described embodiment, and therefore only the line width expansion / reduction unit 23 will be described. .

FIG. 7 shows the configuration of the line width expansion / reduction unit 23 of the first modification. In the above-described embodiment, the line width is delicately controlled by the internal division processing between each output of the maximum value filter unit and the minimum value filter unit of the fixed size reference region and the pixel signal of interest. In the first modification, the line width is controlled by switching the outputs of the maximum value filter unit and the minimum value filter unit having a plurality of reference areas.

First, the image data 15 is input to the filter unit 41. The filter unit 41 has a reference area of 3 × 3, 5 ×
The filter is composed of filters having three sizes of 5, 7 × 7 and a delay circuit, and outputs two types of signals of the maximum value and the minimum value for the image signal of the target pixel and the size of each reference region. That is, the image signal 42, 3 × 3, 5
Maximum value signals 43, 44, 4 in the area of × 5, 7 × 7 pixels
5, 3 × 3, 5 × 5, 7 × 7 pixel area minimum value signal 4
6, 47 and 48 are output.

The averaging unit 49 outputs the signal
An averaging process is performed between adjacent signals of the reference area size. Specifically, signals 42 and 43, signals 43 and 4
4, signals 44 and 45, signals 42 and 46, signals 46 and 4
7, and the signals 47 and 48 are added and averaged for a total of six sets of signals, and the averaged signals 50, 51, 52, 53, 5
4, 55 are output.

Next, the signal selecting section 56 selects one of the signals 42 to 48 and 50 to 55 generated as described above based on the expansion / reduction selection signal 25a and the expansion / reduction amount signal 25b, and outputs the selected signal. Signal 57 is assumed. Here, the relationship between the expansion / reduction selection signal 25a and the expansion / reduction amount signal 25b and the selected signal is shown in FIG.

Next, the meaning of the signal processing in the first modification will be described. For example, the maximum value signal 4 of a 3 × 3 filter
Reference numeral 3 denotes a signal obtained by subjecting image data to expansion processing of one pixel width. Similarly, the maximum value signals 44 and 45 of the 5 × 5 filter and the 7 × 7 filter are signals obtained by subjecting image data to dilation processing of 2 pixel width and 3 pixel width, respectively. The signal obtained by averaging the maximum value signal 43 of the 3 × 3 filter and the maximum value signal 44 of the 5 × 5 filter is a signal that has been subjected to an expansion process of approximately 1.5 pixel width.

Therefore, the signals 48, 42, 50, 4
Reference numerals 3, 51, and 44 are image data obtained by subjecting the original image data to expansion processing in which the expansion width is sequentially increased. Similarly, the signals 52, 45, 53, 46, 54, and 47 are image data in which the reduction width is sequentially increased. Therefore, the expansion / reduction selection signal 25a and the expansion / reduction amount signal 25
b, by selecting these image data,
Expansion and reduction of image data can be controlled.

In the first modified example, although the circuit scale is larger than that of the above-described embodiment, the range of the expansion width and the reduction width can be widened up to a maximum of three pixel widths, and the variation of the line width can be obtained. This is effective for correction of engines with large noise.

Next, a second modification of the present invention will be described. In a full-color printing apparatus, printing is generally performed using four color materials of YMCK. In the above-described embodiment and the first modification, the line width control process is performed on all the color signals of yellow (Y), magenta (M), cyan (C), and black (K). It is not limited to this. For example, there is a modified example in which the line width is controlled only for the signal of the black color material, and the YMC color materials are output as they are.

Generally, a character image has many black characters, and the image quality is greatly affected by the quality of the black characters. Therefore, the image quality can be sufficiently improved only by performing the line width control processing only on the area of the black character. In general image area identification, identifying only black characters is simpler in identification method and higher in identification accuracy than identifying all characters. In the above-described embodiment, line width control is performed in accordance with the image area identification signal. Therefore, if there is an identification error, line width control is performed on the gradation image portion, and adverse effects such as uneven shading occur. For this reason, high identification accuracy is required.
The modified example is effective.

Next, a third modification of the present invention will be described. As a third modification, there is also an example in which the user specifies a control amount of the line width. In the third modification, the user can specify the control amount of the line width via the control panel. For example, a mode is provided in which thick characters are recorded as they are, and thin characters are recorded thicker than the original, and a corresponding switch is provided. If the user specifies the mode, the line width detecting unit is set according to the mode. It can be realized by switching the relationship between the line width and the line width control amount.

As described above, according to the above-described embodiment, regardless of the characteristics of the image output unit, without affecting the density reproduction of the gradation image, a line having a line width faithful to the input image data can be obtained. Can be recorded. By periodically detecting the line recording characteristics of the image output unit, even if the characteristics of the image output unit fluctuate, it can be corrected and a line with a line width faithful to the input image data can be recorded. it can. Further, the line width of characters can be controlled as desired by the user via a control panel or the like.

[0063]

As described above in detail, according to the present invention, it is possible to provide an image processing method capable of faithfully reproducing image data to be recorded, irrespective of the environment and the shape of the image, etc. .

[Brief description of the drawings]

FIG. 1 is a block diagram schematically showing a configuration of an image processing apparatus to which an image processing method according to an embodiment of the present invention is applied.

FIG. 2 is a block diagram illustrating a configuration of a line width control unit.

FIG. 3 is a view for explaining processing of a line width detection unit.

FIG. 4 is a diagram showing contents of a table of a line width control unit.

FIG. 5 is a block diagram illustrating a configuration of a line width expansion / reduction unit.

FIG. 6 is a view for explaining a processing example in a maximum value filter unit and a minimum value filter unit;

FIG. 7 is a block diagram illustrating a configuration of a line width expansion / reduction unit according to a first modification;

FIG. 8 is a diagram illustrating a selection operation in a line width expansion / reduction unit according to a first modification;

[Explanation of symbols]

1 image input unit (image input means) 2 color conversion unit
3 image area identification unit (identification means), 4 filter processing unit, 5 inking unit, 6 line width control unit (line width control unit), 7 gradation processing unit, 8 ... image output unit (image output means), 9 ... line image pattern generation unit (test pattern generation means), 10 ... density measurement unit (measurement means), 21 ...
... Line width detection unit (line width detection unit), 22 ... Line width control amount calculation unit (line width control amount calculation unit), 23 ... Line width expansion / reduction unit (line width expansion / reduction unit), 31 ... Maximum Value filter section, 3
3 ... Minimum value filter section, 35 ... Selection section, 37 ... Line width modulation section, 41 ... Filter section, 49 ... Averaging section,
56 ... Signal selection unit.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tsukasa Takai 70 Yanagimachi, Yukicho, Kawasaki-shi, Kanagawa Prefecture Inside the Toshiba Yanagimachi Plant Co., Ltd. (72) Inventor Hidekazu Sekizawa 70, Yanagimachi, Saiwai-ku, Kawasaki-shi, Kanagawa F-term (reference) 5B057 AA11 CA01 CA16 CD05 CE02 CE05 CE06 CF01 CF02 DA17 5C077 LL02 MM02 MP06 MP07 MP08 NN04 PP02 PP03 PP05 PP15 PP20 PP27 PP28 PP32 PP33 PP38 PP43 PP47 PP51 PP58 PP61 PQ23 RR06 SS01 SS02 TT02 TT06 5C079 HB01 HB02 HB12 KA17 LA06 LA10 LA12 LA15 LA21 LB11 MA10 NA05 PA02 PA03

Claims (1)

[Claims] An image input device reads an image including characters of a document, inputs image data, performs predetermined processing on the input image data, and outputs the image data by an image output device. Detecting a line width of an image included in a character region from the input image data, and performing a line width control process such as enlargement or reduction of the line width on the input image data, Varying the control amount of the line width control process in accordance with the line width detection result.