JP2013066005A - Image forming apparatus and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve visibility of a thin line.SOLUTION: An image forming method includes the steps of: determining a flag related to selected dot data (step S230); when an increase flag=FALSE and a decrease flag=FALSE are related to the selected dot data (step S230 and the increase flag=the decrease flag=FALSE), performing color conversion of the dot data by using a normal LUT (step S240); when the increase flag=FALSE and the decrease flag=TRUE are related to the selected dot data (step S230, the increase flag=FALSE and the decrease flag=TRUE), performing color conversion of the dot data by using a decrease LUT (step S250); and when the increase flag=TRUE and the decrease flag=FALSE are related to the selected dot data (step S230, the increase flag=TRUE and the decrease flag=FALSE), performing color conversion of the dot data by using an increase LUT (step S260).

Description

  The present invention relates to an apparatus and a method for forming an image.

In order to improve the reproducibility of fine lines by printing, a technique is known in which dot data determined to be fine lines is printed with correction for increasing the density. (For example, Patent Document 1)
.

JP 2000-287092 A JP-A-9-62238

According to the technique of Patent Document 1, even if the reproducibility is improved, the visibility is not necessarily improved,
In some cases, it worsened. An object of the present invention is to improve the visibility of fine lines in image formation including printing.

SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

Application Example 1: Drawing element data including drawing start coordinate information, drawing end coordinate information, color information, and thickness information is converted into image formation data, and an image is formed using the image formation data. An image forming apparatus,
An extraction unit that extracts a thin line and an adjacent area adjacent to the thin line from the drawing element data based on the thickness information;
When the result of comparing the color information of the adjacent area and the color information of the fine line with respect to a specific aspect indicates that the visibility of the fine line is worse than a reference, the color information is converted into the image forming data. In this case, the gist includes an adjacent region correction unit that corrects the color of the adjacent region so that the visibility of the thin line is improved.
According to this image forming apparatus, when it is desirable to improve the visibility of the fine line, the visibility of the fine line can be improved by correcting the color of the adjacent region without increasing the fine line. . The “modality” mentioned here is a parameter related to color. Examples of the color parameters include lightness, hue, saturation, luminance, reflectance, and density. A “specific aspect” is at least one of these parameters. “Correcting the color” means changing the above aspect. The aspect to be changed may be the same as or different from the aspect used for the comparison between the adjacent region and the thin line.

Application Example 2: The image forming apparatus described in Application Example 1,
The specific aspect is brightness,
The adjacent area correction unit corrects the brightness of the adjacent area so that the brightness difference is increased when the brightness difference, which is a difference obtained by subtracting the brightness of the thin line from the brightness of the adjacent area, is less than a comparison reference value. This is the gist.
According to this image forming apparatus, the brightness difference with the adjacent region is enlarged, so that the visibility of the thin line is improved. The “lightness difference” can take a positive or negative value. “Enlarging the brightness difference” means increasing the absolute value of the brightness difference.

Application Example 3: The image forming apparatus according to Application Example 2,
When the brightness difference is less than the comparison reference value and the brightness of the adjacent area is equal to or greater than the absolute reference value, the adjacent area correction unit increases the brightness of the adjacent area higher than the brightness indicated by the color information. The gist is to correct as follows.
In this image forming apparatus, when the brightness of the adjacent area is equal to or greater than an absolute reference value, correction is performed to increase the brightness of the adjacent area. That is, the lightness of the originally high adjacent area is corrected to be further increased. Such a correction appears to be small in change. Therefore, according to this image forming apparatus, it is possible to increase the visibility of the thin line and to reduce the influence of the lightness correction of the adjacent region.

Application Example 4: The image forming apparatus according to Application Example 2,
When the brightness difference is less than the comparison reference value and the brightness of the adjacent area is less than the absolute reference value, the adjacent area correction unit makes the brightness of the adjacent area lower than the brightness indicated by the color information. The gist is to correct as follows.
In this image forming apparatus, when the brightness of the adjacent area is less than an absolute reference value, the brightness of the adjacent area is corrected to be low. That is, the lightness of the originally low adjacent area is corrected to be further lowered. Such a correction appears to be small in change. Therefore, according to this image forming apparatus, it is possible to make the influence of the lightness correction of the adjacent region small while increasing the visibility of the thin line.

Application Example 5: The image forming apparatus according to any one of Application Example 2 to Application Example 4,
The comparison reference value is a positive value,
The gist of the adjacent area correction unit is to correct the brightness of the adjacent area to be higher than the brightness indicated by the color information when the brightness difference is equal to or greater than the comparison reference value.
According to this image forming apparatus, the brightness difference with the adjacent region is enlarged, so that the visibility of the thin line is improved.

Application Example 6: The image forming apparatus according to any one of Application Example 2 to Application Example 5,
The gist of the adjacent area correction unit is that the correction is not performed when the brightness difference is smaller than the comparison reference value and less than a second comparison reference value that is a negative value.
If it is not “when the visibility of the thin line is worse than the reference”, for example, it can be defined like this image forming apparatus.

Application Example 7: The image forming apparatus according to any one of Application Example 1 to Application Example 6,
When the visibility of the fine line indicates that it is worse than the standard, the gist is to include a fine line correction unit that corrects the color of the fine line.
According to this image forming apparatus, since the color of the fine line is corrected in addition to the adjacent area, the visibility of the fine line can be further improved. The thin line reference value may be the same as or different from the comparison reference value or the second comparison reference value. The aspect for correcting the thin line may be the same as or different from the aspect for correcting the adjacent region.

Application Example 8: Drawing element data including drawing start coordinate information, drawing end coordinate information, color information, and thickness information is converted into image formation data, and an image is formed using the image formation data. An image forming method comprising:
An extraction step of extracting a thin line and an adjacent area adjacent to the thin line from the drawing element data by the thickness information;
When the result of comparing the color information of the adjacent area and the color information of the fine line with respect to a specific aspect indicates that the visibility of the fine line is worse than a reference, the color information is converted into the image forming data. In this case, the present invention includes an adjacent region correction step of correcting the color of the adjacent region so as to improve the visibility of the thin line.
According to this image forming method, the same effect as that of the image forming apparatus of Application Example 1 can be obtained.
In addition, according to this image forming method, for example, printed matter can be produced.

1 is a schematic configuration diagram of a printing apparatus 10. FIG. 5 is a flowchart showing output image data creation processing. The flowchart which shows a rasterization process. The graph which showed the relationship of the brightness of a thin line | wire and an adjacent area | region, and brightness correction. 6 is a flowchart showing color conversion processing. A graph comparing a reduction LUT, a normal LUT, and an increase LUT.

1. Hardware configuration (Figure 1):
FIG. 1 is a schematic configuration diagram of the printing apparatus 10. The printing apparatus 10 is a color ink jet type, and includes a mechanism that transports a print medium P (white background) by a paper feed motor 74, a mechanism that reciprocates a carriage 80 in the axial direction of a platen 75 by a carriage motor 70, and a carriage 80 A mechanism that forms dots by driving the mounted print head 81 to eject ink, a control unit 30 that controls objects to be controlled (paper feed motor 74, carriage motor 70, and print head 81), a computer and a memory An image data supply unit 91 that acquires input image data from a medium (not shown) and supplies the input image data to the control unit 30 is provided.

The carriage 80 carries ink cartridges 82 to 85 for color ink. The ink cartridge 82 contains cyan ink C, the ink cartridge 83 contains magenta ink M, the ink cartridge 84 contains yellow ink Y, and the ink cartridge 85 contains black ink K. In the print head 81 below the carriage 80, nozzle rows corresponding to the inks described above are formed. When the ink cartridges 82 to 85 are mounted on the carriage 80 from above, ink can be supplied from the ink cartridges 82 to 85 to the print head 81.

The control unit 30 includes a CPU 40, a ROM 51, a RAM 52, and an EEPROM 60.
With. The CPU 40 develops and executes a control program stored in advance in the ROM 51 in the RAM 52, thereby controlling paper feeding and reciprocation of the carriage 80 and driving the print head 81 to eject ink onto the print medium P. To control. The ink ejection program (driver) is for controlling each nozzle.

The input image data supplied by the image data supply unit 91 is composed of a combination of drawing element data as vector data. Vector data represents a drawing element by any one of basic figures. Basic figures include polygonal lines (including line segments), polygons, ellipses (including circles), and Bezier curves. These basic figures include drawing start coordinate information, drawing end coordinate information, color information (RGB values), and thickness information (numerical value indicating line width: unit mm).

The EEPROM 60 stores a color conversion LUT 61. The color conversion LUT 61 is a table for converting RGB color information included in the drawing element data into an ink amount set indicating the amount of ink (CMYK) contained in each of the ink cartridges 82 to 85. Three types are prepared according to the type of element (details will be described later).

2. Output image data creation processing (FIG. 2):
FIG. 2 is a flowchart showing output image data creation processing. The output image data creation process is a process executed mainly by the CPU 40 in order to create output image data from the input image data. It is confirmed that the input image data is supplied from the image data supply unit 91 to the control unit 30. It is a process that is executed when triggered. When the output image data creation processing is started, rasterization processing is executed (step S100).

2-1. Rasterization processing (FIG. 3):
FIG. 3 is a flowchart showing the rasterizing process. First, one of the rendering element data constituting the supplied input image data that has not been rasterized is selected (step S110). The drawing start coordinates are selected in order from the vector data arranged on the top. When the upper and lower positions are the same, the drawing start coordinates are selected in order from the vector data arranged on the left.

Next, the selected drawing element data is rasterized, that is, dot data is formed by converting from the vector format to the raster format (step S120). continue,
A drawing element indicated by the selected drawing element data (hereinafter abbreviated as “selected drawing element”).
) Is a fine line, an adjacent area in contact with the fine line, or another area that is neither a fine line nor an adjacent area (step S130). This determination is performed based on the selected drawing element data and the thickness information included in the drawing element data adjacent to the selected drawing element data. This “adjacent” means sharing at least a part of the boundary line when drawn by vector data.

2-1-1. Adjacent area:
When the selected drawing element is an adjacent area (step S130, adjacent area), the brightness difference with the fine line in contact with the adjacent area is determined (step S145). The lightness mentioned here is the lightness defined by the Munsell color system. Hereinafter, the brightness of the thin line is X, and the brightness of the adjacent region is Y
Also written. If XY ≧ 4 (step S145, XY ≧ 4), the process proceeds to step S170 without correcting the brightness. The reason why the brightness is not corrected when X−Y ≧ 4 is that the fine line has a sufficiently higher brightness than the adjacent region without correction, and the visibility of the fine line is good.

In step S170, it is determined whether all elements have been rasterized. If there is drawing element data that has not been rasterized (NO in step S170), the process returns to step S110.

FIG. 4 is a graph showing the relationship between the brightness of the thin line and the adjacent region, and the brightness correction. That is, it is a graph showing what kind of lightness correction is performed when there is a relationship between the lightness of the thin line and the lightness of the adjacent region. The vertical axis represents the brightness of the adjacent region, and the horizontal axis represents the brightness of the thin line. The case of XY ≧ 4 corresponds to the region (A) in FIG.

On the other hand, when YX ≧ 4 (step S145, YX ≧ 4), the reduction flag is set to TRUE for each dot data generated based on the selected adjacent region (step S164).
). In FIG. 4, it corresponds to the region (B). The initial value of this reduction flag is FALSE, and when it is changed to TRUE, processing for reducing the amount of dot generation is executed in the subsequent halftone processing (step S300). The purpose of reducing the amount of dot generation is to increase the brightness of the adjacent area. As described above, since the print medium P is a white background, the lightness increases as the dot generation amount decreases. The purpose of increasing the brightness is to improve the visibility of the fine line by increasing the brightness difference from the fine line. After step S164, the process proceeds to step S170 described above.

On the other hand, if | X−Y | <4 (step S145, | X−Y | <4), that is, 0 ≦ X.
When −Y <4 or 0 ≦ Y−X <4, it is determined whether the brightness of the adjacent region is 4 or more (step S
155). When the brightness of the adjacent region is 4 or more (step S155, YES), step S1
Proceed to 64 to set the reduction flag to TRUE. In FIG. 4, it corresponds to the area (C).

On the other hand, if the brightness of the adjacent region is less than 4 (step S155, NO), the increase flag is set to TRUE for each dot data generated based on the selected adjacent region (step S
166). This increase flag has an initial value of FALSE, and when it is changed to TRUE, a process for increasing the dot generation amount for the purpose of reducing the brightness of the adjacent area is performed as a subsequent halftone process (step S300). Will be executed. In FIG.
) Corresponds to the area. After step S166, the process proceeds to step S170 described above.

Thus, if | X−Y | <4, that is, if the brightness difference between the thin line and the adjacent region is small, either increase or decrease in the amount of dot generation in the adjacent region is selected and executed. The purpose of performing such processing is to widen the brightness difference from the thin line in any case. The purpose of selecting the way to increase the brightness when the brightness of the adjacent area is 4 or more is to make it appear that the color of the adjacent area has not changed much. This makes use of the fact that when a color with high brightness is corrected, the change is less perceived when the brightness is further increased than when the brightness is decreased. Similarly, the brightness of the adjacent area is 4
The purpose of selecting the method of lowering the brightness when it is less than is less than the change in the color of the adjacent region by using the fact that the lower brightness is less perceptible when correcting the lightness of the low brightness To make it look like.

2-1-2. Fine line:
If the selected drawing element is a thin line (step S130, thin line), the brightness difference from the adjacent area in contact with the thin line is determined (step S140). When XY ≧ 4 (step S140,
X−Y ≧ 4), the process proceeds to step S170 without correcting the lightness. In FIG.
) Corresponds to the area. The reason why the brightness is not corrected in the case of XY ≧ 4 as described above is that, as already described, the visibility of the thin line is good without correction.

On the other hand, when YX ≧ 4 (step S140, YX ≧ 4), the increment flag is set to TRUE for each dot data generated based on the selected thin line (step S162).
In FIG. 4, it corresponds to the region (B). The purpose of increasing the dot generation amount by setting the increase flag to TRUE is to reduce the brightness of the thin line. The purpose of reducing the lightness of the fine line is to increase the visibility of the fine line by increasing the lightness difference with the adjacent region.
After step S162, the process proceeds to step S170 described above.

On the other hand, if | X−Y | <4 (step S140, | X−Y | <4), it is determined whether the brightness of the adjacent region is 4 or more (step S150). When the brightness of the adjacent area is 4 or more (step S150, YES), the process proceeds to step S162, and the increase flag is set to TRUE. In FIG. 4, it corresponds to the area (C).

On the other hand, when the brightness of the adjacent region is less than 4 (step S150, NO), the reduction flag is set to TRUE for each dot data generated based on the selected thin line (step S16).
0). In FIG. 4, it corresponds to the (D) region.

Thus, when | X−Y | <4, the brightness of the fine line is lowered when the brightness of the adjacent area is 4 or more, and the brightness of the fine line is raised when the brightness of the adjacent area is less than 4. That is, the fine line is lowered when the lightness is originally high, and is raised when the lightness is originally low. This is the reverse of the case of the adjacent region, and the color appears to change from the adjacent region. However, since the thin line is often long and narrow compared to the adjacent region, this change is often difficult to perceive.

2-1-3. Other areas:
If the selected drawing element is the other region (step S130, other region), that is, neither the fine line nor the adjacent region, the influence on the visibility of the thin line is small, and the process proceeds to step S170 without correcting the lightness. If it is determined in step S170 that all elements have been rasterized, the rasterization process ends.

2-2. Color conversion process (FIG. 5):
Subsequently, the color conversion process is started (step S200). FIG. 5 is a flowchart showing the color conversion process. Among the dot data formed in the rasterization process, one that has not undergone color conversion is selected (step S210). This selection order follows the procedure of starting from the dot data arranged at the uppermost left, proceeding to the right, and moving to the rightmost leftmost dot data when reaching the rightmost.

Subsequently, the flag associated with the selected dot data is determined (step S).
230). When the increase flag = FALSE and the reduction flag = FALSE are associated (step S230, increase flag = F, reduction flag = F), the color conversion of the dot data using the normal LUT in the color conversion LUT 61 (RGB → CMYK) (step S240)
). The normal LUT is a color conversion LUT that emphasizes color reproducibility.

On the other hand, when the increase flag = FALSE and the reduction flag = TRUE are associated (step S230, increase flag = F, reduction flag = T), the reduction L in the color conversion LUT 61
Color conversion of dot data is performed using the UT (step S250). Reduction LUT is C
A color conversion LU whose MYK ink amount is 0.8 times the normal LUT
T.

When the increase flag = TRUE and the reduction flag = FALSE are associated (step S230, increase flag = T, reduction flag = F), the increase L in the color conversion LUT 61
Color conversion of dot data is performed using the UT (step S260). The increase LUT is C
A color conversion LU in which the value indicating the ink amount of each of MYK is 1.2 times the normal LUT
T.

FIG. 6 shows the amount of ink for printing a certain color, a reduction LUT, a normal LUT, and an increase L.
It is the graph compared in the case of UT. As shown in FIG. 6, the ink amounts by the three LUTs have the relationship described above.

After executing any one of the above-described steps S240 to S260, it is determined whether all the dot data has been color-converted (step S270). If there is dot data that has not yet been converted (step S270, NO), the process returns to step S210, and steps S210 to S270 are repeated until color conversion is performed on all dot data. When all the dot data is color-converted (step S270, YES), the color conversion process is finished.

Subsequently, halftone processing is performed using the color-converted dot data (step S30).
0) The output image data creation process is finished. Although the halftone process is shown as a process having a subroutine in FIG. 2, it is well known and will not be described in detail. Data output through the halftone process, that is, data that is an output result of the output image data creation process is output image data.

The printing apparatus 10 executes printing (image formation) by instructing the control target (paper feed motor 74, carriage motor 70, and print head 81) based on the output image data thus created.

As described above, when the visibility of the thin line is poor, the printing apparatus 10 can improve the visibility of the fine line by widening the brightness difference between the fine line and the adjacent region. In order to widen the brightness difference, as executed by the printing apparatus 10, either the brightness of the thin line is increased to decrease the brightness of the adjacent area, or the brightness of the thin line is decreased to increase the brightness of the adjacent area. It is valid. Regarding which one to select, the printing apparatus 10 places importance on making the color change of the adjacent region appear small. Specifically, when the brightness of the adjacent region is high (in the embodiment, 4 or more), the method of increasing the brightness of the adjacent region by decreasing the brightness of the thin line is selected. The reason is that, as described above, even if the lightness is changed to a higher level, it does not seem to change much. For the same reason, when the brightness of the adjacent region is low (less than 4 in the embodiment), the method of increasing the brightness of the thin line and decreasing the brightness of the adjacent region is selected.

By the way, in each of the regions (B) and (C) shown in FIG. 4, the fine line corresponds to dot increase (lightness decrease) and the adjacent region corresponds to dot reduction (lightness improvement). Therefore, Y = X + 4, which is the boundary line between the (B) and (C) regions, does not function to distinguish the increase / reduction of dots. Y =
X + 4 indicates, as shown in the rasterizing process (FIG. 3), if the adjacent area has a certain level of brightness higher than the thin line (step S140 (145), Y−X ≧ 4), the brightness of the adjacent area is lowered. If the brightness difference between the adjacent area and the thin line is small (step S140 (
145), | X−Y | <4), determination using brightness of adjacent region ”. In the printing apparatus 10, the Y intercept of Y = X + 4 (corresponding to the comparison reference value in the application example) and the lightness 4 as a reference for dividing the (C) and (D) regions (absolute in the application example) (Corresponding to the reference value) coincides with Y = X
+4 is just not working to discriminate dot increase / reduction. If the standard brightness is greater than 4, a part of Y = X + 4 becomes a boundary line with the (B) and (D) areas, and the increase / reduction of dots is distinguished.

3. Correspondence between embodiment and application example:
Step S130 determines the extraction unit and the extraction process, steps S145, 164, 166, 2
Reference numerals 50 and 260 denote the adjacent area correction unit and the adjacent area correction process, steps S145 and S160.
162, 250, and 260 correspond to software for realizing the fine line correction unit.

4). Other embodiments:
The present invention is not limited to the above-described embodiments, and can be implemented in various forms within the technical scope of the invention. For example, additional components in the embodiment can be omitted from the embodiment. The additional components referred to here are elements corresponding to matters not specified in the substantially independent application example. For example, the following embodiments may be used.

In the embodiment, by classifying the brightness difference between the fine line and the adjacent area into three levels, the fine line and the adjacent area are selected from any of the three levels of increasing, decreasing, or maintaining the brightness. Thus, it is not necessary to have three stages. For example, the lightness difference between the fine line and the adjacent region may be classified into four or more stages, and color conversion may be performed to increase the lightness difference as the original lightness difference is smaller.

The aspect used as the standard of classification may be based on the relationship with the visibility of the thin line, not based only on the brightness. It may be based on one or more of lightness, hue, saturation, luminance, reflectance, density, etc., for example, based on an index combining lightness and hue. Similarly, the aspect to be changed is not limited to lightness but may be anything related to the visibility of thin lines. For example, one or more of lightness, hue, saturation, luminance, reflectance, and density are changed. It is possible. The aspect used for the classification criteria and the aspect to be changed may be the same or different.

A configuration may be adopted in which the use of a plurality of color conversion LUTs is stopped based on a user instruction or the like. For example, when high-speed printing is required, all drawing elements may be color-converted by a normal LUT without performing classification based on brightness.

Extraction of the thin line and the adjacent region may be performed based on raster data instead of vector data.
The increase LUT and the reduction LUT may not be stored, but may be calculated from the normal LUT. For example, the value of the normal LUT may be multiplied by a constant.

The values of CMYK need not be changed at the same ratio. For example, only K may be changed by a different ratio. This is because K is a color whose brightness is lower than that of other colors (CMY), and therefore the brightness is lowered even with a smaller dot generation rate than other colors. Each of CMYK may be changed at different ratios.

The dot generation rate may be changed not in the color conversion LUT but in halftone processing. Specific examples of the method include the following.
When the dither method is used, for example, the dot generation rate may be adjusted by using different dither matrices having different values according to the lightness of the drawing element.
When using the error diffusion method, for example, the dot generation rate may be adjusted by correcting the diffusing error according to the brightness of the drawing element.

In addition, the following forms may be used.
-The printer may be for monochrome printing, a laser printer, or a thermal printer.
-A display or a projector may be used.
-Halftone processing may not be used. For example, binarization may be used.
-The brightness may be adjusted by controlling the size of the ink dots.
A process for improving the visibility of thin lines (in the embodiment, output image data creation process) may be executed using a RIP (raster image processor).

DESCRIPTION OF SYMBOLS 10 ... Printing apparatus 30 ... Control unit 40 ... CPU
51 ... ROM
52 ... RAM
60 ... EEPROM
61 ... Color conversion LUT
DESCRIPTION OF SYMBOLS 70 ... Carriage motor 74 ... Paper feed motor 75 ... Platen 80 ... Carriage 81 ... Print head 82-85 ... Ink cartridge 91 ... Image data supply part

Claims (8)

An image forming apparatus that converts drawing element data including drawing start coordinate information, drawing end coordinate information, color information, and thickness information into image forming data and forms an image using the image forming data. There,
An extraction unit that extracts a thin line and an adjacent area adjacent to the thin line from the drawing element data based on the thickness information;
When the result of comparing the color information of the adjacent area and the color information of the fine line with respect to a specific aspect indicates that the visibility of the fine line is worse than a reference, the color information is converted into the image forming data. And an adjacent region correcting unit that corrects the color of the adjacent region so that the visibility of the thin line is improved. The image forming apparatus according to claim 1,
The specific aspect is brightness,
The adjacent area correction unit corrects the brightness of the adjacent area so that the brightness difference is increased when the brightness difference, which is a difference obtained by subtracting the brightness of the thin line from the brightness of the adjacent area, is less than a comparison reference value. Image forming apparatus. The image forming apparatus according to claim 2,
When the brightness difference is less than the comparison reference value and the brightness of the adjacent area is equal to or greater than the absolute reference value, the adjacent area correction unit increases the brightness of the adjacent area higher than the brightness indicated by the color information. The image forming apparatus corrects as follows. The image forming apparatus according to claim 2,
When the brightness difference is less than the comparison reference value and the brightness of the adjacent area is less than the absolute reference value, the adjacent area correction unit makes the brightness of the adjacent area lower than the brightness indicated by the color information. The image forming apparatus corrects as follows. An image forming apparatus according to any one of claims 2 to 4,
The comparison reference value is a positive value,
The adjacent region correction unit corrects the lightness of the adjacent region to be higher than the lightness indicated by the color information when the lightness difference is equal to or greater than the comparison reference value. An image forming apparatus according to any one of claims 2 to 5,
The adjacent region correction unit is an image forming apparatus that does not perform the correction when the brightness difference is smaller than the comparison reference value and less than a second comparison reference value that is a negative value. An image forming apparatus according to any one of claims 1 to 6,
An image forming apparatus including a fine line correction unit that corrects the color of the fine line when the visibility of the fine line is worse than a reference. An image forming method in which drawing element data including drawing start coordinate information, drawing end coordinate information, color information, and thickness information is converted into image forming data, and an image is formed using the image forming data. There,
An extraction step of extracting a thin line and an adjacent area adjacent to the thin line from the drawing element data by the thickness information;
When the result of comparing the color information of the adjacent area and the color information of the fine line with respect to a specific aspect indicates that the visibility of the fine line is worse than a reference, the color information is converted into the image forming data. And an adjacent region correction step of correcting the color of the adjacent region so that the visibility of the thin line is improved.

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