JP2006270655A - Apparatus and method for image processing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image processing apparatus capable of improving image quality by providing an appropriate screen for an image including a highlight portion and an intermediate to high-density portion. <P>SOLUTION: An image processing unit 30 comprises: an input section for inputting image data; a density determination section 321 for separating an image in the image data into a highlight portion and a region other than the highlight portion based on a density value corresponding to a crossing of CinDout characteristics between a screen having the first number of lines and a screen having the second number of lines more than the first number of lines; a screen processing section 36 for performing screen processing by setting the screen having the first number of lines to the highlight portion and setting the screen having the second number of lines to the region other than the highlight portion; and a RAM 70 for storing, in a rewritable manner, the crossing of CinDout characteristics between the screen having the first number of lines and the screen having the second number of lines. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image processing apparatus and an image processing method.

  The number of screen lines is characterized in that the lower the number of lines, the more stable the gradation from the highlight part (the bright part of the image), and the higher the number of screen lines, the better the character reproduction. Actually, for example, when the emphasis is on gradation, a screen near 150 lines is used, and when emphasis is placed on character reproduction, a screen near 300 lines is used. A screen with a low number of lines and a screen with a high number of lines are contradictory characteristics, and when the same screen is used for the entire image, both character reproduction and gradation cannot be satisfied. In order to solve such problems, techniques such as screen switching processing for each object and pictogram separation processing have been proposed in the following patent documents.

In the technique disclosed in Patent Document 1, a tag is added to an image for each object such as a character, a graphic, and an image, and the screen is switched for each tag to improve character reproduction and gradation. ing. In the technique described in Patent Document 2, pictograms are separated, various determinations such as structure extraction and halftone dot extraction are performed on the image path, and the image is separated into black characters, color characters, patterns, etc. The screen is switched for each tag. In the technique described in Patent Document 3, the number of lines is substantially reduced in the low density portion by applying pulse width modulation to the image density signal.
JP-A-6-320802 JP-A-7-107278 JP-A-8-156329

  However, in the screen switching process for each object as in the technique described in Patent Document 1, for example, when characters / lines are present in an image image and characters / lines are present in a portion to which an image tag is added, the normal image portion is displayed. Since it is necessary to apply a low line number screen to improve reproducibility, an appropriate screen (high line number screen) cannot be used for characters and lines.

  In the technique described in Patent Document 2, input images are separated by parameters in pictogram separation. However, in the case of the current algorithm, if a parameter for judging characters in a color background is set, For example, the hair of a part may be erroneously determined as a character, and the character part is usually filled with a high γ TRC (Tone Reproduction Curve) in order to obtain a strong reproduction. A gap will occur. In order to prevent this, it is often necessary to use a parameter that allows the character in the color background to be determined as a design, and an appropriate screen (high line number screen) can be used for the character in the color background. I can't. Further, in the technique described in Patent Document 3, when the number of lines in the low density portion is reduced by pulse width modulation, a problem such as occurrence of a gradation jump occurs.

  Therefore, the present invention has been made in view of the above problems, and an image processing apparatus capable of improving image quality by applying an appropriate screen to an image including a highlight portion and an intermediate to high density portion, and An object is to provide an image processing method.

  In order to solve the above-mentioned problems, the present invention provides an input means for inputting image data, a screen having a first line number, and an output floor of a screen having a second line number higher than the first line number. Separating means for separating an image in the image data into a region other than a highlight portion and a highlight portion based on a density value corresponding to an intersection of tonal characteristics; and the first number of lines with respect to the highlight portion. And processing means for performing screen processing by setting a screen having the second number of lines for an area other than the highlight portion.

  According to the present invention, an intersection point (intersection) between output gradation characteristics (CinDout characteristics) of a low line number screen and a high line number screen is used as a screen switching point, so that the highlight portion has good gradation characteristics. The screen with the number of lines is adapted, and the screen with the number of lines with good character reproducibility can be adapted to the middle to high density part (intermediate / high density part), so that the highlight part and the middle to high density part are included. Image quality can be improved by applying an appropriate screen to the image. Cin is density information, and refers to image data representing density from 0% to 100%. Dout is the output density, which is the image output level of the density sensor for the toner patch. The output gradation characteristic means Dout (image output level) with respect to Cin (image data). The intersection of the CinDout characteristic means a point where the waveform of the CinDout characteristic of the screen having the first number of lines and the waveform of the CinDout characteristic of the screen having the second number of lines intersect.

  The image processing apparatus according to the present invention further includes storage means for rewritably storing an intersection of output gradation characteristics of the screen having the first number of lines and the screen having the second number of lines. The image processing apparatus of the present invention further includes storage means for storing an intersection of output gradation characteristics of the screen having the first number of lines and the screen having the second number of lines according to the number of output colors.

  The separating unit adjusts an intersection of output gradation characteristics of the screen having the first number of lines and the screen having the second number of lines.

  When the density within a predetermined range from an intersection of output gradation characteristics of the screen with the first number of lines and the screen with the second number of lines is equal to or less than a predetermined ratio of the entire image, It is characterized in that the process of separating into areas other than the highlight part is not performed. According to the present invention, when the density lower than the screen switching point by a certain percentage (or the upper density) is equal to or lower than the certain value of the entire image, the switching process which is not desired by the user by not performing the screen switching process. Can be prevented.

  The screen having the second number of lines has a screen line number that is an integral multiple of the screen having the first number of lines, for example. According to the present invention, the number of lines on the high line number screen is set to be an integral multiple of the number of lines on the low line number screen, thereby preventing the occurrence of screen moiré when switching to a different line number for each color. I can do it.

  The image processing apparatus of the present invention further includes a determination unit that determines an image in the image data as at least one of a graphic area and an image area based on tag data associated with the image data, and the separation unit includes The area determined as the graphic area or the image area by the determining means based on the density value corresponding to the intersection of the output gradation characteristics of the screen with the first line number and the screen with the second line number. The highlight portion and the region other than the highlight portion are separated. According to the present invention, by applying a process of switching between a low line number screen and a high line number screen to a graphic image area, a screen with a high line number for intermediate / high density portions such as characters / lines in the area. Therefore, reproducibility can be improved.

  The image processing apparatus of the present invention further includes a determination unit that determines a pattern area based on tag data associated with the image data, and the separation unit includes the first line number screen and the second line number. Separating the area determined as the pattern area by the determination unit into the area other than the highlight area and the highlight area based on the density value corresponding to the intersection of the output gradation characteristics of the screen with the number of lines. It is characterized by. According to the present invention, it is possible to improve the reproducibility of intermediate / high density portions such as characters / lines in an area by applying a process of switching between a low line number screen and a high line number screen to the pattern determination area.

  The present invention includes a step of inputting image data, a density value corresponding to an intersection of output gradation characteristics of a screen having a first line number and a screen having a second line number higher than the first line number. A step of separating an image in the image data into a highlight portion and a region other than the highlight portion, setting the screen of the first line number for the highlight portion, and the highlight portion An image processing method comprising: setting a screen having the second number of lines for a region other than the above and performing screen processing. According to the present invention, a screen having a good gradation is applied to the highlight portion by using the intersection point of the output gradation characteristics of the low line number screen and the high line number screen as a screen switching point. Since a screen having a line number with good character reproducibility can be applied to the middle and high density portions, the image quality can be improved. The image processing method of the present invention further includes a step of adjusting an intersection of output gradation characteristics of the screen having the first number of lines and the screen having the second number of lines.

  According to the present invention, it is possible to provide an image processing apparatus and an image processing method capable of improving image quality by applying an appropriate screen to an image including a highlight portion and an intermediate to high density portion.

  Hereinafter, the best mode for carrying out the present invention will be described. Hereinafter, a case where the present invention is applied to a copying machine will be described as an example. FIG. 1 is a block diagram of a copying machine 10 according to an embodiment of the present invention. As shown in FIG. 1, the copier 10 includes an image input unit (IIT) 20, an image processing unit 30, and an image output unit (hereinafter referred to as “IOT”) 40. The image input unit 20 reads an image from a document and acquires image data. The image processing unit 30 performs various image processes on the image data acquired by the image input unit 20. The image output unit 40 records an image on an image recording medium such as recording paper using color materials of Y (yellow), M (magenta), C (cyan), and K (black) based on the image data. Output. This will be described in detail below.

  The image input unit 20 includes an exposure light source 21 and an image sensor (CCD: Charge-Coupled Devices) 23. Light irradiated from the exposure light source 21 is irradiated onto the reading document 22 and detected by the image sensor 23. The image processing unit 30 includes a LUT (Look Up Table) 31, a pixel attribute determination unit 32, a filter 33, an enlargement / reduction processing unit 34, a TRC processing unit 35, and a screen processing unit 36. The image processing unit 30 can be configured using, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like. The CPU controls the operation and processing of each component according to the control program stored in the ROM. The RAM is used as a work area for the CPU.

  The LUT 31 converts the RGB signal input from the image input unit 20 into, for example, a uniform color space signal L * a * b * that does not depend on the device. The pixel attribute determination unit 32 determines the attribute of the pixel included in the image data. The filter 33 enhances the sharpness by emphasizing edges for binary images such as characters and line drawings, and smoothes halftone images such as photographs and halftone prints to remove moire and halftone dots. Filter processing is performed to improve smoothness and graininess.

  The enlargement / reduction processing unit 34 performs processing for enlarging or reducing the image data according to the set enlargement rate or reduction rate. The TRC processing unit 35 performs gradation correction processing in accordance with the characteristics of the image output unit 40 using a lookup table in which the output density with respect to the input density is written. The screen processing unit 36 performs processing for generating a halftone image from a multi-valued image by screen processing, and creates a page image for each page. For this screen processing, for example, a Dither method or an error diffusion method is used. The image output unit 40 prints out image data as a visible image on a medium such as paper using electrophotographic technology. The operation unit 50 includes buttons and the like for the user to perform mode setting and the like. A user interface is displayed on the display unit 60.

  FIG. 2 is a diagram illustrating a configuration of the halftone processing unit 100 in the image processing unit 30. As shown in FIG. 2, the halftone processing unit 100 includes the screen processing unit 36 shown in FIG. The screen processing unit 36 includes a density determination unit 321, a highlight unit screen processing unit 361, and a screen processing unit 362 for intermediate / high density units.

  The RAM 70 stores the Cin value at the intersection of the CinDout characteristics of the low line number screen and the high line number screen in a rewritable manner. When there are a plurality of output colors, the RAM 70 stores the intersection of the CinDout characteristics of the low line number screen and the high line number screen by the number of outputs according to the number of output colors. For example, when the output colors are four colors of YMCK, the RAM 70 stores the Cin value of the intersection of the CinDout characteristics of the low line number screen and the high line number screen for these four colors. This is because the CinDout characteristics of the low line number screen and the high line number screen are different for each color.

  The density determination unit 321 first determines the density value of the pixels in the input image data for each pixel. Next, the density determination unit 321 includes, for example, a 150 line low line number screen (first line number screen) and a 300 line high line number screen (second line number) higher than the first line number. The value of Cin at the intersection of the CinDout characteristic is read out from the RAM 70. Next, the density determination unit 321 highlights an image in the input image data based on the density value corresponding to the Cin value at the intersection of the CinDout characteristics of the low line number screen and the high line number screen. Separate into areas other than.

  The density determination unit 321 refers to the histogram of the image taken at the time of the job, and the density within a predetermined range from the intersection of the CinDout characteristics of the low line number screen and the high line number screen is equal to or less than a predetermined ratio of the entire image. In other words, in other words, when the density (or density above) of a certain percentage below the screen switching point is below a certain value of the entire image, processing is performed to separate the highlight area and the area other than the highlight area. You may make it not. Thereby, the switching process which a user does not want can be prevented.

  When the density in a predetermined range from the intersection of the CinDout characteristics of the screen with the first line number and the screen with the second line number is equal to or less than a predetermined ratio of the entire image, the density determination unit 321 The process of separating the area is not performed. For example, assuming that the intersection of the CinDout characteristics is 35%, the result of referring to the histogram by the density determination unit 321 is that the area of 35% or less excluding Cin0% (area without image) is the entire image excluding Cin0%. If it is 1% or less, the process of separating the highlight area and the area other than the highlight area is not performed.

  The highlight portion screen processing unit 361 performs screen processing by setting a screen having a low line number of 150 lines for the highlight portion. The intermediate / high density portion screen processing unit 362 performs screen processing by setting a 300-line high-line number screen for the intermediate / high density region other than the highlight portion. Halftone image data generated by the highlight screen processing unit 361 and the intermediate / high density screen processing unit 362 is output to the image output unit 40. In this way, the density determination unit 321 has conventionally been necessary by switching the screen with a low line number and a screen with a high line number for each pixel at the stage of screen processing corresponding to Cin of the input image. In addition, addition of a tag and a complicated circuit become unnecessary.

  FIG. 3 is a diagram for explaining a crossing point of the CinDout characteristic. In FIG. 3, the horizontal axis represents image data Cin representing density from 0% to 100%. When expressed from 0 to 255 gradations, 0% corresponds to 0 gradations and 100% corresponds to 255 gradations. The vertical axis represents the image output level Dout of the density sensor for the toner patch formed corresponding to the image data Cin. The CinDout characteristic of the 150-line screen is indicated by a broken line, and the CinDout characteristic of the 300-line screen is indicated by a solid line. When the 150-line screen is applied to the highlight portion and the 300-line screen is applied to the intermediate / high-density portion, the density determination unit 321 determines the point at which the waveforms of the CinDout characteristics of the two screens intersect. As a switching point.

  Here, the value of Cin at the intersection of the CinDout characteristics of the screen with a low line number of 150 lines and the screen with a high line number of 300 lines is 35%. For this reason, the density determination unit 321 corresponds to Cin 35% using a density value corresponding to Cin 35% of the intersection of the CinDout characteristics of the screen with a low line number of 150 lines and the screen with a high line number of 300 lines as a screen switching point. A pixel having a density value lower than the density value is determined to be a highlight portion, a screen having a low line number of 150 lines is applied, and a pixel having a density value higher than the density value corresponding to Cin 35% is medium / high density. A screen with a high line number of 300 lines is applied.

  As a result, a 150-line screen with good gradation is applied to the highlight part of the image, and a 300-line screen with good character reproducibility is applied to the middle / high density part. -Good results can be obtained with both character reproduction. In addition, since the screen is switched at a point where CinDout intersects, no gradation jump occurs.

  The point at which the waveform of the CinDout characteristic intersects is stored in the RAM 70 of FIG. 2 as a parameter, and the density determination unit 321 refers to it when determining the highlight part and the medium / high density determination part. When processing a color image, parameters are stored in the RAM 70 for each toner color. That is, when the output colors are Y, M, C, and K, the parameters for these four colors are stored in the RAM 70.

  FIG. 4 is a diagram illustrating a setting example of a low line number screen and a high line number screen. The line number of the high line number screen is set to be an integral multiple of the line number of the low line number screen. Here, when the screen used by the highlight screen processing unit 361 is a 150-line screen, the screen used by the intermediate / high-density screen processing unit 362 is a 300-line screen. Thus, by setting the number of lines on the high line number screen to be an integral multiple of the number of lines on the low line number screen, it is possible to prevent the occurrence of screen moiré when switching to a different line number for each color. .

  FIG. 5 is an example of a user setting screen (UI display) used when correcting a screen switching point. As shown in FIG. 5, the operation unit 50 includes a button 61 for manually correcting the screen switching point, a window 62 for displaying the current switching point, buttons 63 and 64 for raising and lowering the screen switching point, and all pixels. Are provided with a button 65 for applying a low line number screen, a button 66 for applying a high line number screen to all pixels, and a button 67 for automatically correcting a screen switching point. The operation unit 50 is displayed on the display unit 60 of FIG. 1 as a user interface. When the screen switching point is automatically corrected, the screen switching point can be corrected by selecting the manual button 61 and selecting the number of screens, all low line number screens, and all high line number screens. On the other hand, when it is desired to automatically correct the switching point, the screen switching point can be automatically corrected on the apparatus side by selecting the auto button 67.

  Next, an example in which the density determination unit 321 automatically adjusts the intersection of the CinDout characteristics of the low line number screen and the high line number screen will be described. FIG. 6 is a flowchart of the screen switching point correction process automatically. FIG. 7 is a diagram illustrating an example of a pattern image used when the switching point correction process is performed. FIG. 9 shows an example in which the pattern image shown in FIG. 7 is flowed on the transfer belt, and the reflected light of the pattern image is read and stored in 255 gradations. FIG. 10 shows a storage example of the switching point RAM 70. In FIG. 10, the Cin value at the intersection of the CinDout characteristics of the 150-line screen and the 300-line screen is stored as a switching point for each of Y, M, C, and K colors. The density determination unit 321 refers to the screen switching point for each color. In step S1, the pattern image shown in FIG. 7 is flowed on the transfer belt. In step S2, the reflected light of the pattern image is read and stored in 255 gradations. In step S3, the density determination unit 321 performs switching point correction processing. FIG. 9 shows the result of reading the reflected light of the pattern image in step S2. In this case, since the low line number screen and the high line number screen intersect at Cin 35%, the switching point is set to 35%. This process is performed for each color of YMCK to obtain switching points for four colors. In step S4, the density correction unit 321 writes the switching point in the RAM 70 and ends the automatic correction process.

  Next, an example of manually adjusting the intersection of the CinDout characteristics of the low line number screen and the high line number screen will be described. FIG. 8 is a process flowchart for manually correcting the switching point. In step S11, processing for outputting a built-in pattern image is performed. In step S12, the output pattern image is set in the image input unit 20. In step S13, the output pattern is scanned (read). In step S14, the density determination unit 321 performs switching point correction processing. In step S15, the density determination unit 321 writes the switching point in the RAM 70, and ends the switching point correction process.

  FIG. 11 is a diagram illustrating an image path representing an example of processing when the processing of the present invention is added to the screen switching processing for each object. Reference numeral 30 denotes an image processing unit, 70 denotes a RAM, and 200 denotes a halftone processing unit. The image processing unit 30 has a function of performing a screen switching process for each object. The halftone processing unit 200 includes a tag determination unit 201 and a screen processing unit 36. The screen processing unit 36 includes a density determination unit 321, a text screen processing unit 371, a highlight screen processing unit 372, and a middle / high density screen processing unit 373.

  The operation of the halftone processing unit 200 will be described. Image data and Tag data are input to the Tag determination unit 201. The tag determination unit 201 determines whether the image in the image data is a text, graphic area, or image area based on the tag data associated with the image data. If the image is text, the tag determination unit 201 proceeds to the text screen processing unit 371. In the case of a graphic area or an image area, the image data is sent to the density determination unit 321. The text screen processing unit 371 performs screen processing suitable for text. Based on the density value corresponding to the intersection of the CinDout characteristics of the low line number screen and the high line number screen in the RAM 70, the density determination unit 321 selects a graphic area or an image area other than the highlight part and the highlight part. Separate into areas.

  The highlight unit screen processing unit 372 performs screen processing using a low-line-number screen having 150 lines. The intermediate / high density screen processing unit 373 performs screen processing using a 300-line high-line number screen. In this way, by adding processing to switch between a low-line screen and a high-line screen to the graphic image area, the reproducibility can be improved because the high-line screen is applied to characters and lines in the area. I can do it.

  FIG. 12 is a diagram illustrating an image path representing an example of processing when the processing of the present invention is added to the pictogram separation processing. In FIG. 12, reference numeral 30 denotes an image processing unit, 70 denotes a RAM, and 300 denotes a halftone processing unit. The image processing unit 30 has a function of performing pictogram separation processing. The halftone processing unit 300 includes a tag determination unit 301 and a screen processing unit 36. The screen processing unit 36 includes a density determination unit 321, a black character screen processing unit 381, a color character screen processing unit 382, a highlight unit screen processing unit 383, and an intermediate / high density unit screen processing unit 384.

  The operation of the halftone processing unit 300 will be described. Image data and Tag data are input to the Tag determination unit 301. A tag determination unit 301 determines any one of a black character region, a color character region, and a design region based on tag data associated with image data. In the case of a black character region, screen processing is performed by the black character screen processing unit 381, and in the case of a color character region, screen processing is performed by the color character screen processing unit 382. The density determination unit 321 separates the pattern area into an area other than the highlight part and the highlight part based on the density value corresponding to the intersection of the CinDout characteristics of the low line number screen and the high line number screen in the RAM 70. .

  The highlight portion screen processing unit 383 performs screen processing using a 150-line low-line screen for the highlight portion, and the intermediate / high-density portion screen processing portion 384 includes an intermediate / high-density portion. Is subjected to screen processing using a 300-line high-line screen. In this way, by adding processing for switching between a low line number screen and a high line number screen for the pattern area, the reproducibility of characters and lines in the area can be improved.

  According to the above-described image processing unit, a 150-line screen with good gradation is applied to the highlight portion of the image, and a 300-line screen with good character reproducibility is applied to the middle / high density portion of the image. Thus, the image quality can be improved. This effect corresponds to the characteristics of each output device and changes in the state, and the same effect can be obtained. The effect of improving the image quality can be further enhanced by combining with existing processing such as screen switching processing for each object and pictogram separation.

  The image processing method according to the present invention is realized using, for example, a CPU, ROM, RAM, and the like, and the program is installed from a hard disk device, a portable storage medium such as a CD-ROM, DVD, or a flexible disk, or the like. Each step is realized by downloading from the communication circuit and executing this program by the CPU.

  The program also includes a step of inputting image data, a density value corresponding to an intersection of output gradation characteristics of a screen having a first line number and a screen having a second line number higher than the first line number. Separating the image in the image data into a highlight portion and a region other than the highlight portion, setting the screen having the first line number for the highlight portion, and other than the highlight portion A step of setting a screen having the second number of lines for the region and performing screen processing is executed by the computer. The program further causes the computer to execute a step of adjusting an intersection of output gradation characteristics of the screen having the first line number and the screen having the second line number. The density determination unit 321 corresponds to a separation unit, the screen processing units 361, 362, 371 to 373, and 381 to 384 correspond to a processing unit, the RAM 70 corresponds to a storage unit, and the LUT 31 corresponds to an input unit.

  Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the specific embodiments, and various modifications, within the scope of the gist of the present invention described in the claims, It can be changed.

1 is a block diagram of a copying machine 10 according to an embodiment of the present invention. 2 is a diagram illustrating a configuration of a halftone processing unit 100 in the image processing unit 30. FIG. It is a figure for demonstrating the intersection point of a CinDout characteristic. It is a figure which shows the example of a setting of a low line number screen and a high line number screen. It is an example of a user setting screen used when correcting a screen switching point. It is a flowchart of the correction process of a screen switching point automatically. It is a figure which shows the example of the pattern image used at the time of switching point correction processing implementation. It is a process flowchart at the time of correct | amending a switching point manually. This is an example in which the pattern image shown in FIG. 7 is flowed on the transfer belt, the reflected light of the pattern image is read and stored in 255 gradations. It is a storage example of RAM70 of a switching point. It is a figure which shows the image path showing an example of the process in the case of adding the process of this invention to the screen switching process for every object. It is a figure which shows the image path showing an example of a process in the case of adding the process of this invention to a pictogram separation process.

Explanation of symbols

10 Copier 20 Image Input Unit 30 Image Processing Unit 31 LUT
32 pixel attribute determination unit 32 density determination unit 33 filter 34 enlargement / reduction processing unit 35 TRC processing unit 36 screen processing unit 361 highlight unit screen processing unit 362 intermediate / high density screen processing unit 40 image output unit

Claims (10)

Input means for inputting image data;
Based on the density value corresponding to the intersection of the output gradation characteristics of the screen having the first line number and the screen having the second line number higher than the first line number, the image in the image data is Separating means for separating the light portion and the area other than the highlight portion;
Processing means for setting a screen having the first line number for the highlight portion and setting a screen having the second line number for an area other than the highlight portion to perform screen processing. An image processing apparatus. 2. The image processing apparatus according to claim 1, further comprising: a storage unit that rewritably stores an intersection of output gradation characteristics of the screen having the first line number and the screen having the second line number. 2. The image according to claim 1, further comprising storage means for storing an intersection of output gradation characteristics of the screen having the first line number and the screen having the second line number in accordance with the number of output colors. Processing equipment. The image processing apparatus according to claim 1, wherein the separation unit adjusts an intersection of output gradation characteristics of the screen having the first number of lines and the screen having the second number of lines. When the density within a predetermined range from an intersection of output gradation characteristics of the screen with the first number of lines and the screen with the second number of lines is equal to or less than a predetermined ratio of the entire image, The image processing apparatus according to claim 1, wherein a process of separating the area other than the highlight portion is not performed. The image processing apparatus according to claim 1, wherein the screen having the second line number has a screen line number that is an integral multiple of the screen having the first line number. Based on tag data associated with the image data, further comprising a determination means for determining an image in the image data as at least one of a graphic area and an image area;
The separation means determines the graphic area or the image area by the determination means based on a density value corresponding to an intersection of output gradation characteristics of the screen having the first line number and the screen having the second line number. The image processing apparatus according to claim 1, wherein the processed region is separated into the highlight portion and a region other than the highlight portion. A determination unit for determining a pattern area based on tag data associated with the image data;
The separation means is an area determined as the pattern area by the determination means based on a density value corresponding to an intersection of output gradation characteristics of the screen having the first number of lines and the screen having the second number of lines. The image processing apparatus according to claim 1, wherein the image processing device is separated into the highlight portion and a region other than the highlight portion. Inputting image data;
Based on the density value corresponding to the intersection of the output gradation characteristics of the screen having the first line number and the screen having the second line number higher than the first line number, the image in the image data is Separating into areas other than the light part and the highlight part;
Setting a screen with the first line number for the highlight portion, and setting a screen with the second line number for an area other than the highlight portion, and performing screen processing. An image processing method characterized by the above. The image processing method according to claim 9, further comprising a step of adjusting an intersection of output gradation characteristics of the screen having the first number of lines and the screen having the second number of lines.

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