JP2002112022A - Image formation device, image formation method, and recording medium capable of reading computer recording image formation program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image formation device by which a user can freely select an image area among a plurality of kinds of image areas that can be separated, and specify the adjustment contents of image characteristic for each of selected image areas. SOLUTION: An area selection screen 200 is displayed on a touch panel. It is provided with area selection keys 201 to 204 which accept the selection of image area by a user among a character area, a photo area, and a background area that can be separated respectively. When a desired area selection key is pressed, a screen for specifying the adjustment contents of concentration or color balance is displayed in every selected image area. As a result, the concentration or color balance is adjusted in every selected image area according to the specified adjustment contents and an image is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, an image forming method, and a computer-readable recording medium on which an image forming program is recorded.

[0002]

2. Description of the Related Art In some cases, image data obtained by reading a document includes a plurality of types of image areas such as a character area, a photograph area, a graphic area, and a background area. 2. Description of the Related Art Conventionally, in order to perform image processing suitable for each attribute such as characters and photographs, an area separation process of separating image data into image areas has been performed.

A technique for correcting an image for each image area separated by the area separation processing is disclosed in, for example, Japanese Patent Laid-Open No.
No. 4,482, and JP-A-11-342647. In particular, according to the electrophotographic apparatus described in JP-A-11-342647, it is possible to adjust the image characteristics for each separated image area. As a result, for example, in a character area, printing can be performed with a high density so as not to be blurred, and in a photographic area, printing can be performed with a low density so that a high gradation portion can be sufficiently expressed. In addition, a technique has been proposed in which, when printing is performed based on image data having a plurality of types of image areas, necessary correction is performed only for a photographic area.

[0004]

However, according to these prior arts, the processing performed for each image area is fixed for each device. Therefore, the user:
It is not possible to specify the adjustment of the image characteristics for each image area as desired. For example, when the user wants to adjust the density, the user can only specify the density as a whole of the image data, and cannot specify the density for each image area.

The present invention has been made to solve the above problems. Therefore, an object of the present invention is to allow a user to freely select an image area from a plurality of types of image areas that can be separated into areas, and further, for each of the selected image areas, such as density or color balance. It is an object of the present invention to provide an image forming apparatus, an image forming method, and a recording medium on which an image forming program can be designated, which can specify adjustment contents.

[0006]

(1) An image forming apparatus according to the present invention is used in an image forming apparatus for forming an image on a sheet based on image data from a plurality of types of image areas which can be separated. Area accepting means for accepting selection of an image area by a user, adjustment content accepting means for accepting a designation by a user for adjustment of image characteristics for each selected image area, and separating image data into a plurality of types of image areas The image processing apparatus further includes a region separating unit and an adjusting unit that adjusts an image characteristic based on a specified adjustment content for each selected image region.

(2) The image forming apparatus has reading means for reading an original and generating image data.

(3) The area separating means (1) or (2) converts the image data into a character area, a photograph area, a graphic area,
And separate into background areas.

(4) The adjusting means of (1) to (3) above
Adjust the density.

(5) The adjusting means of the above (1) to (3)
Adjust the color balance.

(6) In an image forming method according to the present invention, in an image forming method for forming an image on a sheet based on image data, a user selects an image area from a plurality of types of image areas which can be separated. Accepting,
A step of receiving a user's specification of the adjustment of the image characteristics for each selected image area; a step of separating the image data into a plurality of types of image areas; and a step of specifying the adjustment content specified for each of the selected image areas. Adjusting the image characteristics based on the image characteristics.

(7) A computer-readable recording medium according to the present invention is a computer-readable recording medium on which an image forming program is recorded, and includes an image by a user from a plurality of types of image areas which can be separated. A step of receiving a selection of an area, a step of receiving, by a user, a specification of adjustment of image characteristics for each selected image area, a step of separating image data into a plurality of types of image areas, Adjusting the image characteristics based on the specified adjustment content for each time.

[0013]

Embodiments of the present invention will be described below with reference to the accompanying drawings. An example in which the image forming apparatus according to the present invention is applied to a copying machine will be described.

FIG. 1 is a block diagram showing the configuration of a copying machine according to the present invention.

The copying machine 100 has a scanner unit 110, an image processing unit 120, and a printer unit 130. Note that, unlike the present embodiment, the scanner and the printer may be provided in different housings.

The scanner section 110 reads a document to obtain image data.

The image processing section 120 processes the input image data. The image processing unit 120 separates the image data into a plurality of types of image regions such as a character region, a photograph region, a graphic region, and a background region. The image processing unit 120
Accepts the selection of the image area by the user from the separable image areas, and accepts the designation of the adjustment contents of the image characteristics for each selected image area.

The "character area" refers to an image area including a character portion. The “photo region” refers to an image region including a photo portion, and is an image region that is relatively smoothly expressed with a halftone density. The “graphic area” refers to an image area including a line drawing graphic or the like. The “background area” is the scanner unit 1
Reference numeral 10 denotes an image area of the same color as the ground color of the document read. “Separation of image area” means to extract a specific image area from image data.

The printer unit 130 prints out on paper based on the image data whose image characteristics have been adjusted.

The image processing section 120 has the following configuration.

The CPU 121 controls the entire copying machine 100. The RAM 122 temporarily records data.
The ROM 123 stores various control programs. The hard disk 124 is used for spooling image data obtained by reading a document.

The operation panel 125 displays an area selection screen for receiving selection of an image area for adjusting image characteristics from a user. Further, the operation panel 125 displays a density / color balance adjustment screen for accepting a designation by the user for the adjustment content of the image characteristics for each selected image area. Preferably, operation panel 125 is a touch panel. Therefore, the user can easily select an image area and specify adjustment contents of image characteristics by pressing a predetermined portion on the area selection screen and the density / color balance adjustment screen.

The scanner interface 126 is an interface for connecting the scanner unit 110 and the image processing unit 120. The printer interface 127
This is an interface for connecting the printer unit 130 and the image processing unit 120.

FIG. 2 is a block diagram showing a software configuration of the copying machine.

The copying machine 100 has an image processing program 140 and a designation receiving program 150 in addition to a normal control program (not shown).

The image processing program 140 performs processing for separating image data into a plurality of types of image areas and adjusting image characteristics for each of the separated image areas. The designation receiving program 150 displays an area selection screen and a density / color balance adjustment screen on the operation panel 125, and also receives selection of an image area for adjusting image characteristics and designation of adjustment contents of image characteristics.

The character area separating section 141 separates a character area from the image data. Figure / photo area separation unit 14
2 separates both the graphic region and the photograph region from the remaining image data from which the character region has been separated. At this time, a photograph area and a graphic area are distinguished.

The combining unit 143 combines the image data of each image area after the image area to which each pixel belongs is determined by dividing the image data into a plurality of types of image areas. The color conversion unit 144 converts image data represented by RGB into image data represented by CMYK.

The image characteristic conversion unit 145 adjusts image characteristics for each image region separated by the character region separation unit 141.

It should be noted that, unlike the present embodiment, it is also possible to execute image processing using a dedicated IC instead of the image processing program 140. In this case, the CPU 121
Transmits the adjustment contents of the image characteristics specified by the user to the dedicated IC. The dedicated IC performs image processing according to the specified adjustment content.

The copying machine configured as described above performs the following processing.

FIG. 3 is a flowchart showing the processing contents of the copying machine. 3 is stored as a program in the ROM 123 or the hard disk 120, and is executed by the CPU 121.

In step S100, it is determined whether an instruction to adjust the image characteristics for each image area (hereinafter referred to as "area-specific adjustment") has been received. If the instruction for adjustment by region has not been received (step S100: N
O), the process of step S101 is performed. As a result, a normal copying process is performed and the process ends. on the other hand,
If the instruction for adjustment by region has been received (step S100: YES), the process of step S102 is executed.

In step S102, selection of an image region for which image characteristics are to be adjusted, and designation of adjustment of image characteristics in the region are accepted.

In step S103, it is determined whether an instruction to start the copying process has been received. When the instruction to start the copying process is received (step S103: YE
S), the process of step S104 is performed, and if the start instruction has not been received (step S103: N
O), the copier 100 waits until a start instruction is received. Specifically, it is detected that the user has pressed a start button (not shown).

In step S104, reading of the document is started. When copying a plurality of pages of an original, the originals are automatically sent to the scanner unit 110 continuously by an ADF (automatic original feeder) (not shown).

In step S105, the image data obtained by reading the document is analyzed, and the image data is separated into a plurality of types of image areas.

In step S106, the image data of each image area is synthesized.

In step S107, the image data represented by RGB is converted into data represented by CMYK.

In step S108, a region-by-region adjustment process is performed. Specifically, based on the image area selected in step S102 and the specified image characteristic adjustment content, the image characteristics are adjusted in accordance with the adjustment content specified for each selected image region.

In step S109, the image data whose image characteristics have been adjusted is output to the printer unit 120 as print data. As a result, the printer unit 120 performs printout.

The following is a detailed description of the image area selection reception processing, adjustment specification designation reception processing, area separation processing, and area-specific adjustment processing.

FIG. 4 is a flowchart showing an example of an image area selection reception process and an adjustment content designation reception process. FIG. 4 shows the processing content of step S102 in FIG. 3 in detail.

In step S200, an area selection screen is displayed, and a user's selection of an image area for adjusting image characteristics is accepted.

FIG. 5 schematically shows an area selection screen.

The area selection screen 200 includes an operation panel 125
Displayed above. The area selection screen 200 is provided with area selection keys 201 to 204 corresponding to image areas that can be separated by the area separation processing described later. The copying machine 100 according to the present embodiment can separate image data into four types of image areas: a character area, a photograph area, a graphic area, and a background area. Therefore, the area selection screen 200 is provided with a character area selection key 201, a photograph area key 202, a graphic area key 203, and a background area key 204. Further, the area selection screen 200 is provided with a cancel key 205 for canceling the input contents. Further, the area selection screen 200 displays an OK button pressed by the user when the specification of the image characteristic adjustment content is completed for all the image areas desired by the user.
A key 206 is provided.

In step S201 in FIG. 4, it is determined whether an image area has been selected from among a plurality of types of image areas. Specifically, the area selection key 20 shown in FIG.
It is confirmed whether or not 1 to 204 have been pressed by the user. If an image area has been selected (step S20)
1: YES), the process of step S202 is performed.
If no image area has been selected (step S20)
1: NO), and waits until an image area is selected.

In step S202, as processing when an image area is selected, a density / color balance adjustment screen corresponding to the selected image area is displayed, and the density and color balance are adjusted for each selected image area. Accept the specification of the content by the user.

FIG. 6 schematically shows a density / color balance adjustment screen.

The density / color balance adjustment screen 300 includes a density designation portion 301 and a color balance designation portion 30.
2 are provided. Further, an OK key 305 which is pressed by a user after designating the adjustment contents of the image characteristics for one image area is provided. OK key 305
When the button is pressed, the screen returns to the area selection screen 200, and a state in which another image area is selected is received. Further, a cancel key 304 is provided to cancel the adjustment content.

The density designation portion 301 accepts designation of density adjustment contents for each selected image area. The color balance designation portion 302 receives designation of color balance adjustment content for each selected image area. The density is specified using, for example, relative values of -3, -2, -1, 0, +1, +2, and +3. Also, the color balance, that is, cyan (C), magenta (M), yellow (Y),
The ratio of each basic color of black (K) is set by relatively specifying the color (saturation) of cyan (C), magenta (M), yellow (Y), and black (Bk). Note that the larger the positive (+) value of the designated value, the higher the density or color, and the larger the designated negative (-) value, the lower the density or color. Since the density / color balance adjustment screen 300 is displayed on the operation panel 125 which is a touch panel, it is possible to easily specify the adjustment content of the image characteristics such as the density and the color balance by pressing the portion where the value is displayed. Can be. In addition, as shown in FIG.
By pressing the portion where is displayed, it is also possible to specify the adjustment content of the density and the color balance.

In step S203, it is determined whether or not the adjustment contents of the image characteristics have been designated. When the adjustment content of the image characteristics is designated (step S203: YE
S), the process of step S204 is performed. If the adjustment content of the image characteristics is not specified (step S2
03: NO), and waits until the adjustment contents of the image characteristics are designated. Specifically, when the user presses the OK key 303, the designation of the adjustment content for the corresponding image area is determined.

In step S204, the adjustment contents specified for each image area are temporarily stored in the RAM 123.

In step S205, the area selection screen 20
0 is displayed again.

In step S206, it is determined whether or not a reception processing completion instruction has been received from the user. Specifically, whether or not the OK key 206 has been pressed on the area selection screen 200 is confirmed. If the instruction completion instruction has been received (step S206: YES), the process ends, and the process returns. On the other hand, if the instruction completion notification has not been received (step S206: NO), step S2
Returning to 01, it is determined whether or not another image area has been selected.

By repeating the above processing, it is possible to receive the specification of the adjustment of the density and the color balance for each area selected by the user from the plurality of types of image areas.

Next, the contents of the area separation processing will be described.

FIG. 7 is a flowchart showing an example of the area separating process. FIG. 7 shows the processing content of step S105 in FIG. 3 in detail.

In step S300, a character area is separated from image data obtained by reading a document.

The separation of the character area can be performed based on pattern matching, similarly to ordinary OCR (optical character reader) software.
In addition, characters often have a uniform color and have a uniform character size (font size). Therefore, the color of the part surrounded by the edge (contour) is uniform,
In addition, when adjacent edges are connected, it is possible to separate a character region by determining whether or not the connected edges fall within a predetermined rectangle. Further, it is also possible to separate the character area by decomposing the image data into frequency components and detecting a frequency unique to the character area. Note that the decomposition into frequency components is the same as that used in general discrete cosine transform (DCT) and the like, and a detailed description thereof will be omitted.

In step S301 of FIG. 7, a graphic area and a photograph area are separated from the image data from which the character area has been removed.

In step S302, the graphic region and the photograph region are removed.

In step S303, the remaining image area (remaining area) from which the graphic area and the photograph area have been removed is recognized as the background area.

FIGS. 8 and 9 are flowcharts showing an example of a process for separating a graphic region from a photograph region. FIGS. 8 and 9 show the processing content of step S301 in FIG. FIG. 10 is a diagram schematically showing the processing contents.

In step S400, a histogram between edges in the main scanning direction is calculated. Specifically, FIG.
An edge 401 illustrated in (A) is detected. next,
Between edges facing each other along the main scanning direction (for example, FIG.
(Between A and B shown in FIG. 3) is detected. By organizing the detected results, a histogram, that is, lightness and its appearance frequency (Hist1
A graph displaying [i]) is created.

FIGS. 11A and 11B show examples of histograms between edges in the main scanning direction. The horizontal axis is the brightness, and the vertical axis is the appearance frequency of the brightness. FIG. 11A shows a histogram in a graphic area, and FIG. 11B shows a histogram in a photograph area.

In steps S401 to S404, the frequency of appearance (Hi
Based on the degree of variation in st1 [i]), a graphic area and a photograph area are distinguished. When the degree of variation is large, the area is separated as a graphic area, and when it is small, the area is separated as a photographic area.

Specifically, the following processing is performed.

In step S401, step S400
A histogram is calculated by smoothing the histogram as the raw data calculated in. Specifically, FIG.
By fitting a predetermined regression curve as shown by a bold line in FIG. 1, the frequency of appearance (Hist2 [i]) in the smoothed histogram is calculated.

In step S402, Hist1 [1]
And Hist1 [2] are calculated for each lightness, and the absolute values of the differences in all the lightnesses are summed to obtain a feature amount (= Σ | Hist1 [1] −Hist1).
[2] |) is calculated.

In step S403, a threshold value T is calculated according to the number of pixels between edges. The threshold value T is obtained by dividing the number of pixels between edges by a predetermined constant.

In step S404, it is determined whether or not the feature value is less than the threshold value T. If the feature value is less than the threshold value T (step S404: YES), the line between edges along the main scanning direction is determined to belong to the photographic area. On the other hand, when the feature amount is equal to or larger than the threshold value T (step S404: NO), the line between the edges along the main scanning direction is determined to belong to the graphic area.
As shown in FIG. 10A, the area separation in the main scanning direction is repeated at a predetermined scanning interval. Note that FIG.
Indicates a line determined to belong to the photograph area.

When the processing is completed up to the last pixel (step S407), the area separation in the main scanning direction is completed, and the subsequent processing in FIG. 9 is executed.

In step S408 in FIG. 9, it is determined whether or not there is a line portion determined as a photographic area between edges in the sub-scanning direction. If there is a line portion determined to be a photographic region by the process of step S405 (step S408: YES), the area between the edges in the sub-scanning direction is separated as a photographic region, and if it does not exist (step S408: NO), the area between the edges in the sub-scanning direction is separated as a graphic area. As shown in FIG. 10B, the area separation in the sub-scanning direction is repeated at a predetermined scanning interval.

The interval (CB) between edges in the sub-scanning direction in FIG.
In (between), there are four line portions determined to be a photographic area, and this area is separated as a photographic area.

When the processing has been completed up to the last pixel (step S411: YES), the area separation in the sub-scanning direction is completed. By the above processing, finally, the edge 401
The image area surrounded by is separated as a photograph area or a graphic area.

As a result of the above processing, the image data is divided into a character area, a photograph area, a graphic area, and a background area. The result of the area separation is stored in the RAM 12 as a map.
2 is stored.

FIG. 12 shows an example of the map. Region information J is assigned to each pixel. Specifically, first, area information “01” is assigned to each pixel belonging to the character area, and then,
Region information “11” and “10” are assigned to each pixel belonging to the photograph region and each pixel belonging to the graphic region.
Further, the remaining pixels are given area information “00” as belonging to the background area.

Next, an example of the adjustment processing for each area will be described.

FIG. 13 is a flowchart showing an example of the adjustment processing for each area. FIG. 13 is a flowchart showing step S10 in FIG.
8 will be described in detail.

According to the present embodiment, the adjustment of the image characteristics for each image area, specifically, the adjustment of the density and the color balance is executed when performing the γ conversion. Where γ
The conversion is generally performed using a gamma correction table (look-up table: LUT). Here, the γ correction table is a table for assigning output pixel values to input pixel values. The density adjustment and the color balance adjustment designated by the user can be performed by shifting the data of the γ correction table.

In step S500, a correction coefficient for shifting the γ correction table data for each selected image area is obtained. Density / color balance adjustment screen 3 for each image area selected using area selection screen 200 in FIG.
The correction coefficient is obtained according to the density designated by 00 and the relative value (-3 to +3) of the CMYK color balance.

More specifically, a correction coefficient table showing the relationship between the relative values (−3 to +3) of the density and the CMYK color balance specified on the density / color balance adjustment screen 300 and the correction coefficients is referred to. The correction coefficient table is stored in the ROM 123 or a non-volatile RAM (not shown).

FIG. 14 is a diagram schematically showing a correction coefficient table.

In the correction coefficient table, designated relative values and correction coefficients are associated one-to-one. Therefore, by referring to the correction coefficient table, a correction coefficient corresponding to the adjustment content of the designated image characteristic is obtained. The correction coefficients include a density correction coefficient Ag, C (cyan), magenta (M),
Correction coefficients Ac, A for yellow (Y) and black (K)
m, Ay, and Ak. In the present embodiment, each of the correction coefficients Ag, Ac, Am, Ay, and Ak is set for each of the character area, the photograph area, the graphic area, and the background area.
It is temporarily stored in M123. FIG. 15 shows an example of the table for each image area.

In step S501, a pixel value is obtained (step S501). Specifically, each pixel value of CMYK is obtained.

In step S 502, the area information J (“00”, “01”, “10”, or “11”) corresponding to the target pixel is read from the map in the RAM 122.

In step S503, a γ correction table corresponding to the target pixel is obtained. The γ correction table is provided for each image region so that appropriate processing is performed according to each image region. Based on the γ correction table, an output pixel value in a case where there is no instruction from the user for density and color balance adjustment is calculated.

Further, each correction coefficient A corresponding to the pixel of interest
g, Ac, Am, Ay, and Ak are acquired with reference to the image area-specific table. Using these correction factors,
The output density is adjusted.

FIG. 16 is a flowchart showing the processing contents of step S503.

In step S600, referring to the map shown in FIG. 12, image area information J = “0” of the pixel of interest.
It is determined whether it is "0". Area information J = “00”
(Step S600: YES), the process proceeds to step S601 to obtain a γ correction table for the background area, and to set the correction coefficients Ag, Ac, Am,
Ay and Ak are obtained. On the other hand, the area information J =
If not “00” (step S600: NO),
Proceed to step S602.

Similarly, in step S602, J = 0
In the case of 1 (Step S602: YES), Step S602
Proceeding to 603, a gamma correction table and a correction coefficient for the character area are obtained. If J is not 01 (step S
602: NO), and proceed to step S604. Step S
If J = 10 in 604 (step S60)
4: YES), the process proceeds to step S605, and a γ correction table and a correction coefficient for the graphic area are obtained. On the other hand, if J is not 10 in step S604 (step S604: NO), that is, if J is 11, a γ correction table and a correction coefficient for the photograph area are obtained.

Returning to FIG. 13, in step S504, output pixel values C ′, C ′,
M ', Y', K 'are calculated. The output pixel values are the respective input pixel values C, M, Y, and K, and the regular (unspecified by the user) output assigned to the input pixel values according to the gamma correction table obtained in step S503. Pixel values γ [C], γ [M], γ [Y], γ [K];
Based on the correction coefficients Ag, Ac, Am, Ay, and Ak,
Is calculated. Specifically, the output pixel value is calculated by the following equation. C ′ = γ [C] × Ag × Ac (1) M ′ = γ [M] × Ag × Am (2) Y ′ = γ [Y] × Ag × Ay (3) K ′ = γ [ K] × Ag × Ak (4) where γ [C], γ [M], γ [Y], γ [K] are
This is a normal output pixel value obtained using the γ correction table set for each image area.

Ag is a correction coefficient for the density of the target pixel.

Ac is a C (cyan) correction coefficient of the target pixel.

Am is a correction coefficient for M (magenta) of the target pixel.

Ay is a Y (yellow) correction coefficient of the target pixel.

Ak is a correction coefficient for k (black) of the target pixel.

By the above equations (1) to (4), the output pixel value of each color according to the adjustment of the image characteristic specified for each image area is calculated, and the partial density adjustment processing is realized.

As is clear from the equations (1) to (4), according to the partial density adjustment processing, the ratio of the output pixel value to the input pixel value is adjusted. Therefore, according to the partial density adjustment processing, it can be said that the γ correction table is adjusted according to the image characteristic adjustment content received for each image area.

FIG. 17 schematically shows the relationship between the input pixel value and the output pixel value. The horizontal axis is the input pixel value, and the vertical axis is the output pixel value. Note that the example shown in FIG. 17 shows a case where the color balance is not adjusted.

When the relative value of the density specified on the density / color balance adjustment screen 300 is 0, that is, when the density is not adjusted, the correction coefficient Ag = 1 as shown in the correction coefficient table of FIG. . Therefore, the output pixel value is a value automatically set using the γ correction table.

On the other hand, when the relative value of the designated density is +3, the correction coefficient Ag is 1.3. Therefore, the output pixel value is higher than the automatically set pixel value. When the density value of each color is represented by 8 bits,
The pixel value is indicated by a gradation from 0 to 255. Therefore, when the output pixel values obtained by the calculations of the expressions (1) to (4) are equal to or greater than 255, the output pixel values are all
255 is set.

If the relative value of the designated density is -3, the correction coefficient Ag is 0.7. Therefore, the output pixel value is lower than the automatically set pixel value. Here, the output pixel value corresponds to the output density.

According to the copying machine 100 of the present embodiment, unlike the case where the γ conversion is simply performed automatically according to each image area, the user designates the adjustment of the image characteristics for each image area. be able to.

A specific example of the processing by the copying machine 100 according to the present embodiment will be described.

A case in which the region-specific adjustment processing is applied to the image shown in FIG. 18 will be described.

If there is no difference in density or color (saturation) between the background area 601 and the character area 602, and it is difficult to identify a character, for example, a background area is selected as follows, and the selected background area is selected. And the color (saturation) can be adjusted.

Specifically, the background area key 204 is pressed by the user on the area selection screen 200 shown in FIG. As a result, the copier 100 accepts the selection of an image area for adjusting image characteristics. Further, on the density / color balance adjustment screen 300 shown in FIG. 6, the user can select -1 as the content of density adjustment, C = + 2, M = 2, Y = + 1, K = 0 as the content of color balance adjustment. Is specified.
As a result, the copying machine 100 accepts the designation of the image characteristic adjustment content for the selected background area.

Referring to the correction coefficient table shown in FIG. 14, the correction coefficient corresponding to the background area is Ag (background) =
0.9, Ac (background) = 1.2, Am (background) = 0.
8, Ay (background) = 1.1 and Ak (background) = 1.0. The correction coefficients corresponding to the character area, the graphic area, and the photograph area are all 1.

Therefore, the output densities are (1) to (4)
By substituting these values into the formula, it is calculated as follows.

For the pixels belonging to the background area, the output density of each color is C ′ = γ [C] × 1.08, M ′ = γ
[M] × 0.72, Y ′ = γ [Y] × 0.99, K ′ =
γ [K] × 0.90. On the other hand, for pixels belonging to an image area other than the background area, the output density of each color is C ′
= Γ [C] × 1.0, M ′ = γ [M] × 1.0, Y ′ =
γ [Y] × 1.0 and K ′ = γ [K] × 1.0.

As a result, the color of the image in the background area changes to light blue or the like, and the density decreases. On the other hand, the colors and densities of images in other image areas do not change.

Similarly, it is possible to specify the adjustment of the image characteristics for each image area, such as decreasing the density in the background area and increasing the density in the character area.

In order to faithfully reproduce the image of the original, the user can select not to specify the adjustment of the image characteristics. Also, the degree of adjustment of the density and the color balance can be freely specified. Therefore, it is possible to form an image that satisfies the user's request, as compared with a normal copying machine.

As a result of the area determination, two or more different types of image areas may overlap each other. If there is a pixel in the overlapping image area, the image area to which the pixel belongs can be virtually determined according to a preset priority, and the process can proceed. For example, it is desirable to set the priority order of the character area and the graphic area higher than the other image areas. In this case, when a certain pixel belongs to the character area and the photograph area, the pixel is virtually determined to belong to the character area, and the process proceeds according to the above-described procedure.

The present invention is not limited to only the above-described embodiments, but can be variously modified within the scope of the claims.

For example, in the above description, the case where the density and the color balance are adjusted for each image area by multiplying by the correction coefficient has been described, but the present invention is not limited to this case. In the case of a monochrome copying machine, there is no need to have a configuration for receiving designation of the content of color balance adjustment.
Further, the image characteristics for which adjustment content can be specified for each image area are not limited to the density and the color balance, but may be, for example, sharpness. In this case, the adjustment of the sharpness is realized by a normal process of calculating a high frequency component included in the image using a spatial filter and adding the calculated result to the original image.

According to the present invention, it is possible to receive a selection of an image region desired by a user from a plurality of types of image regions that can be separated, and to adjust image characteristic adjustment contents specified for each selected image region. Any image forming apparatus and image forming method capable of forming an image based on the image may be used.

In the above-described embodiment, the image forming process can be performed by the CPU 121 executing a predetermined program describing the above-described processing procedure. The predetermined program is a computer-readable recording medium such as a flexible disk or a CD.
-It may be provided by a ROM or the like.

[0121]

As described above, according to the present invention, selection of an image area by a user from a plurality of types of image areas that can be separated is accepted, and image characteristics are adjusted for each selected image area. The contents can be specified by the user, and the image characteristics can be adjusted for each selected image area based on the specified adjustment contents. Therefore, the user can freely select an image area from a plurality of types of image areas that can be separated, and can specify adjustment contents such as density or color balance for each selected image area. it can. As a result, the user can make fine designations, and can realize image formation that satisfies the user's wishes.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a copying machine according to the present invention.

FIG. 2 is a block diagram illustrating a software configuration of the copying machine.

FIG. 3 is a flowchart showing processing contents of the copying machine.

FIG. 4 is a flowchart illustrating an example of an image area selection receiving process and an adjustment content designation receiving process.

FIG. 5 is a diagram schematically showing an area selection screen.

FIG. 6 is a diagram schematically illustrating a density / color balance adjustment screen.

FIG. 7 is a flowchart illustrating an example of a region separation process.

FIG. 8 is a flowchart illustrating an example of a process of separating a graphic region from a photograph region.

FIG. 9 is a flowchart subsequent to FIG. 8;

FIG. 10 is a diagram schematically showing the contents of a process for separating a graphic region from a photograph region.

FIG. 11 is a diagram showing a histogram between edges in the main scanning direction.

FIG. 12 is a diagram illustrating an example of a map in which region information is assigned to each pixel.

FIG. 13 is a flowchart illustrating an example of processing for adjusting image characteristics for each selected image area.

FIG. 14 is a diagram schematically showing a correction coefficient table.

FIG. 15 is a diagram schematically illustrating an image area-specific table.

FIG. 16 is a flowchart showing the processing content of step S503 in FIG.

FIG. 17 is a diagram schematically illustrating a relationship between an input pixel value and an output pixel value.

FIG. 18 is an example of an image to which a region-specific adjustment process is applied.

[Explanation of symbols]

 100: Copy machine, 110: Scanner unit, 120: Image processing unit, 130: Printer unit, 140: Image processing program, 150: Designation reception program, 200: Area selection screen, 300: Density / color balance change screen

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Claims (7)

[Claims] 1. An image forming apparatus for forming an image on a sheet based on image data, an area receiving means for receiving a selection of an image area by a user from a plurality of types of image areas which can be separated, and For each image area, an adjustment content receiving means for receiving a specification of the adjustment of the image characteristics by the user, an area separating means for separating the image data into a plurality of types of image areas, An image forming apparatus comprising: adjusting means for adjusting an image characteristic based on adjustment contents. 2. The image forming apparatus according to claim 1, further comprising a reading unit that reads an original to generate image data. 3. The image forming apparatus according to claim 1, wherein the area separating unit separates the image data into a character area, a photograph area, a graphic area, and a background area. 4. The image forming apparatus according to claim 1, wherein said adjusting unit adjusts a density. 5. The image forming apparatus according to claim 1, wherein the adjusting unit adjusts a color balance. 6. An image forming method for forming an image on a sheet based on image data, wherein a step of receiving a selection of an image area by a user from a plurality of types of image areas which can be separated into areas, Receiving, by each user, the specification of the image characteristic adjustment content; separating the image data into a plurality of types of image areas; and, for each of the selected image areas, adjusting the image characteristic based on the specified adjustment content. Adjusting the step of: an image forming method. 7. A computer-readable recording medium on which an image forming program is recorded, wherein a step of receiving a selection of an image area by a user from a plurality of types of image areas which are separable, and a selected image area Receiving, by each user, the specification of the image characteristic adjustment content; separating the image data into a plurality of types of image areas; and, for each of the selected image areas, adjusting the image characteristic based on the specified adjustment content. A computer-readable recording medium on which an image forming program is recorded.