JP4793874B2 - Image processing apparatus, image processing method, program, and recording medium - Google Patents

Description

  The present invention relates to an image processing apparatus including a toner save mode for outputting toner (coloring material) while saving consumption (normally).

  In addition to a normal output mode that generates and outputs a high-quality image, there is an apparatus that includes a toner save mode that saves and outputs toner (powder toner, liquid toner (ink)) more than usual. The toner save mode is basically used when image quality is not important, for example, when checking the layout of an output image. Conventional methods for saving toner consumption include a method of density conversion, a method of taking a logical product of a dither image and a thinning pattern, a method of performing pulse width modulation and writing light amount control, and the like. Since all of these methods output with the image density lowered, the image quality is inferior to that in the normal output mode. However, even in the toner save mode, there is a demand for maintaining the readability without degrading the image quality particularly for the character image having a high importance.

  For example, there is a method of switching toner save processing with reference to object information (see, for example, Patent Document 1). Since the printer has object information such as text, graphics, and photos, it can easily switch between processes, such as performing toner save on other objects without performing toner save on only text, and also providing good image quality. It is. However, since there is no object information in copying, toner saving processing equivalent to that of a printer cannot be performed.

  Patent Document 2 is a toner save process that can be realized by copying and has good character readability, detects an edge in an image, does not perform a toner save process at an edge portion, and saves toner at a non-edge portion. It is a device that performs. However, as in Patent Document 2, when toner save processing is performed by copying, the image quality is inferior to toner save processing using object information in a printer. The toner save process using object information is stored in the density including the inside of the character, but the technique of Patent Document 2 that detects the edge and stores the density only in the edge portion performs the toner save process inside the character, and is legible. However, the image quality is reduced.

  Further, Patent Document 3 targets a business color manuscript, performs edge detection and chromatic / achromatic determination, and does not perform toner save processing on edge portions only for chromatic pixels as in Patent Document 2. The toner save process is performed on the non-edge portion. Further, the achromatic pixel does not perform toner save processing at all, so that the density of black characters / color characters with higher importance (usually high frequency) including the inside of the characters is stored. However, since the apparatus of Patent Document 3 does not perform toner save processing for achromatic pixels at all, no toner save processing is performed for black character originals on gray dots. In order to maximize the toner reduction effect without impairing the image quality of black characters, the gray dot portion of the background should be output with a lower density. In addition, since no toner saving process is performed on the achromatic portion in the pattern image, there is a problem that the image quality is uncomfortable and the toner reduction effect is not improved.

JP 2001-219626 A JP 2002-86805 A JP 2005-59444 A

By the way, general character manuscripts and map manuscripts have the following properties.
-In the case of characters on gray halftone dots, the density of the background halftone dots is not so high, and there are very few cases where the halftone dot ratio exceeds 40%.
In the case of a character with a color halftone dot, the background halftone part has a high density and may be solid with a halftone dot ratio of 100% (for example, a black character on a yellow solid).

  The first object of the present invention is to use the above-described properties to reproduce black characters with high image quality up to the inside of the characters when the toner save mode is set, maintain the legibility of the color characters, and character background portions (gray backgrounds, An object of the present invention is to provide an image processing apparatus, an image processing method, a program, and a recording medium that exhibit the maximum toner reduction effect in a color background.

  The second object of the present invention is to further provide an image processing apparatus, an image processing apparatus, and an image processing apparatus that improve the toner reduction effect by suppressing a sense of incongruity in image quality by performing toner save processing according to attributes such as a pattern portion in an image. A processing method, a program, and a recording medium are provided.

The present invention is to provide an image including an achromatic signal and chromatic signal, and an output mode without saving color material consumption, the image processing apparatus having a toner save mode to save color material consumption, the image When an edge detection means for detecting an edge and the toner save mode is set, an output value for the input value is predetermined when the input value of the achromatic color signal is equal to or less than a first threshold with respect to the achromatic color signal. When the input value exceeds the first threshold and is equal to or lower than the second threshold, the output value is reduced as the input value increases and the second threshold is used to reduce the output value. Applying a non-linear characteristic that converts the input value to an output value so that the input value and the output value are equal when the input value exceeds the second threshold value, and the ratio of reducing the output value is set to 0, The edge of the chromatic signal In contrast, a linear first characteristic that converts the input value into an output value so that the input value and the output value of the chromatic color signal are equal to each other is applied, and the non-edge of the chromatic color signal is A toner save processing unit configured to perform toner save processing by applying a second linear characteristic of converting the input value to the output value by reducing the output value with respect to the input value of the chromatic color signal at a predetermined ratio ; The most important feature.

(1) When the toner save mode is set, the toner save process is switched according to the edge, density, and color, so that the properties of a general document can be utilized to the maximum, and a high-quality toner save process can be performed particularly with respect to character image quality. .

(2) When the toner save mode is set, the density is relatively stored at the chromatic edge or the achromatic high density portion, so that high-quality reproduction of high-density black characters, which are particularly important among black characters, and color character readability It is possible to achieve both maintenance and improvement of the toner reduction effect of the character background portion (gray background, color background).

(3) When the toner save mode is set, the density is relatively preserved at the edge or achromatic non-edge high density portion, so that high-quality reproduction of high density black characters which are particularly important among black characters, color characters and low density Both the readability of gray characters can be maintained and the toner reduction effect of the character background portion (gray background, color background) can be improved.

(4) When the toner save mode is set, the highest density is stored at the edge, and then relatively high density is also stored at the achromatic non-edge high density part. In addition, the improvement of the toner saving effect can be achieved by a simple method while suppressing the deterioration level.

(5) When the toner save mode is set, since the toner save process is switched according to the edge, density and color at the halftone dot portion, the low density gray character on the white background is reproduced with high image quality, while the halftone dot portion It can achieve high-quality reproduction of black characters, maintain readability of color characters, and reliably reduce toner in the character background.

(6) When the toner save mode is set, the toner save process is switched according to the edge, density, and color in the non-white background portion, so that the toner can be surely reduced particularly in a low-density bold text, a solid image, or a continuous tone image. In the non-white background portion, it is possible to achieve high-quality reproduction of black characters, maintain the legibility of color characters, and reliably reduce toner in the character background portion.

(7) Since the toner saving process is switched according to the edge, density, and color in a text document or a map document, the image quality is high and there is no sense of incongruity, and the toner saving process with a high toner reduction effect can be performed.

(8) When the image quality mode is character priority, the toner save process is switched according to the edge, density, and color, so that there is a character high image quality and a toner reduction effect in the character background according to the user's request. Toner save processing can be performed.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

Example 1:
FIG. 1 shows the configuration of Embodiment 1 of the present invention. The scanner 10 obtains image data composed of RGB signals by reading a document, and the scanner γ correction unit 11 corrects the γ characteristics of the scanner, and converts the reflectance linear signal into a density linear signal. The scanner color correction 12 converts the RGB signal depending on the scanner characteristics into a device-independent R′G′B ′ signal that does not depend on the scanner.

  The operation panel 30 can select and specify the toner save mode when the user wants to output in the toner save mode. It is also possible to select and specify the type of document from (1) character / photo document, (2) character document, (3) photo document, and (4) map document. In addition to this, the selection of the document type may be performed using a conventional technique for automatically determining the document type.

  The filter 13 performs a smoothing process that suppresses the undulation of the halftone dot portion and suppresses moire, and an edge enhancement process that increases the sharpness of the character portion. Switching according to the type of original, (2) text originals and (4) map originals emphasize edge sharpening with emphasis on character sharpness, and (3) photographic originals emphasize smoothing with emphasis on moire suppression. (1) In the case of a character / photo original, an intermediate intensity edge enhancement process and a smoothing process are performed.

  The printer color correction unit 14 performs conversion from a device-independent R'G'B 'signal to a C'M'Y' signal depending on printer characteristics. The black processing unit 15 generates a K signal according to the C′M′Y ′ data (black generation), and reduces the amount according to K from the C′M′Y ′ (under color removal (UCR)). Do. CMYK corresponds to the color material color of the printer. Although there are a method for performing both black generation and UCR using an equation, a method using an LUT, and the like, in this embodiment, a case where black generation is performed using an LUT and UCR is performed using an equation will be described.

FIG. 2 is a black generation LUT. In black generation, the minimum value Min (C ′, M ′, Y ′) of C ′, M ′, Y ′ (0 is white, 255 is black) is calculated and input to the LUT to obtain an output value. . UCR is performed by the following equation (1). α is a UCR adjustment parameter.
C = C′−α × K
M = C′−α × K
Y = C′−α × K (Formula 1)
Both black generation and UCR are switched depending on the type of document. For (2) text manuscripts and (4) map manuscripts, the black generation table-1 is used, Min (C, M′Y ′) is replaced with K as it is, and the UCR adjustment parameter is α = 1. (3) In the photo original, the black generation table-3 is used, and K is not generated in the highlight, but K is gradually generated from the middle. The UCR adjustment parameter is α = 0.5. (1) For a character / photo original, the black generation table-2 is used so that the ink is higher than the photo original. The UCR adjustment parameter is α = 0.8.

  FIG. 3 shows the configuration of the edge detection means 20. For each color C′M′Y ′, the edge amount detection means 200, 201, 202 detects multivalued edge amounts. FIG. 4A shows the configuration of the edge amount detection means 200, 201, 202. Each of the edge amount detection filters 1 to 4 performs a masking operation using four types of 7 × 7 filters shown in FIGS. Of the four outputs, the one having the maximum absolute value is selected by the maximum value selection means 217 and output.

  In FIG. 3, the maximum value selection unit 203 selects the maximum edge amount of the detected three colors, and the binarization unit 204 compares the preset threshold value with the edge amount to determine the edge amount. If it is equal to or greater than the threshold, 1 is output, and if it is less than the threshold, 0 is output. On the other hand, the signal synthesizing unit 205 adds the three signals C′M′Y ′ at a predetermined ratio and converts them into one signal. For example, (C ′ × 1/4 + M ′ × 2/4 + Y ′ × 1/4) is output as a synthesized signal. The Laplacian filter calculation means 206 performs a masking calculation on the synthesized signal using the filter of FIG. 4 (f), and the sign determination means 207 determines whether or not it is a positive value. 0 is output. The AND operation unit 208 outputs 1 representing an edge when both the output value of the binarization unit 204 and the output value of the sign determination unit 207 are 1.

  FIG. 5 shows the result of edge detection at a character edge. The edge amount responds at the edge portion, and a positive value is output (output 203 in FIG. 3). Laplacian is output as a positive value on the high density side of the edge corresponding to the inner edge of the character, and as a negative value on the low density side of the edge corresponding to the outer edge of the character (output of 206 in FIG. 3). Since the Laplacian sign determination is added, the edge amount becomes valid only at the inner edge where the Laplacian is positive, and the edge amount becomes invalid at the outer edge where the Laplacian is negative. Finally, the inner edge of the character is detected as an edge.

  When the user designates the toner save mode, the toner save processing unit 16 switches the toner save processing according to the signal indicating the type of document from the operation panel 30 and the edge detection result from the edge detection unit 20.

  The toner saving process is performed by γ conversion having the characteristics shown in FIG. When the toner save γ1 is used, the input value = the output value, the density is stored as it is, and the toner save process is not substantially performed. When toner save γ2 is used, a process is performed in which the output value is about 50% of the input value. When toner save γ3 is used, processing is performed in which the output value is 50% of the input value near the input value 0 to 110 on the low density side, and density preservation processing is performed on the high density side.

  When the document type is (2) a character document and (4) a map document, as shown in FIG. 6B, toner save γ corresponding to the edge detection result is applied to the K signal and the CMY signal. For CMY signals, toner save γ of γ1 at the edge portion and γ2 at the non-edge portion is applied. Therefore, density saving is performed at the edge portion of the color character, and toner save processing is performed with a value of 50% at the non-edge portion. Is done. In the case of a character image on a color halftone dot (for example, yellow), a toner save process in which the value of the halftone dot portion as the background is 50% is applied. Since the toner save γ of γ3 is applied to the K signal, the density is preserved at the edge portion and non-edge portion (= inside the character) of the black character excluding the low density gray character. Toner save processing is performed for low-density gray text, but the appearance rate of low-density gray text is low in general manuscripts, and it is originally dark if it is important information that you want to retain when setting toner save. Often written in letters. In the case of a character image on a gray halftone dot, a toner save process with a value of 50% is performed on the background halftone dot portion. If the background halftone ratio exceeds 50%, the toner save processing is not performed and the density is saved. However, in general originals, there are few gray backgrounds where the halftone percentage exceeds 40%.

  When the document type is (1) character / photo original, as shown in FIG. 6C, toner save γ corresponding to the edge detection result is applied to the K signal and CMY signal. For both the CMY signal and the K signal, the toner save γ of γ1 at the edge portion and γ2 at the non-edge portion is applied, and the toner save processing is performed to save the density at the edge portion and 50% at the non-edge portion. Even with halftone dots and photographic paper photos, only the edges will be stored in density, but compared to the case where (2) text originals or (4) map originals are selected, there is less sense of incongruity in the picture parts, and toner saving effect is also achieved. Rise.

  When the document type is (3) a photographic document, as shown in FIG. 6D, toner save γ corresponding to the edge detection result is applied to the K signal and the CMY signal. Regardless of edge or non-edge, the toner save γ of γ2 is always applied and the toner save processing of 50% reduction is performed uniformly, so that there is no sense of incongruity in halftone dot patterns and photographic paper photographs.

  In this embodiment, toner save γ1 is used that substantially disables toner save processing. However, if a γ table that reduces the degree of toner save even if it is not disabled is used, this is used. A close effect can be expected.

  The image after the toner save is processed by the printer γ correction unit 17 and the pseudo halftone processing unit 18, and the printer 19 outputs the image onto a recording medium. The printer γ correction unit 17 performs conversion processing using a density conversion table in accordance with the density characteristics of the printer. The pseudo halftone processing means 18 performs pseudo halftone processing such as dithering and error diffusion.

  As described above, according to the present exemplary embodiment, when the toner save mode is set, in a character document or a map document, high-quality reproduction of high-density black characters, which are more important among black characters, maintenance of legibility of color characters, character background portion (gray background, It is possible to improve both the toner reduction effect of the color background.

Example 2:
FIG. 7 shows a configuration of the second embodiment of the present invention. The difference from the first embodiment is that the second embodiment includes an attribute determination unit 40.

FIG. 8A shows the configuration of the attribute determination unit 40 of this embodiment, and the attribute determination unit 40 of this embodiment includes a halftone dot separation unit 41. FIG. 8B shows the configuration of the halftone dot separating means 41. Halftone dot separation is performed using a method based on peak pixel detection. In the peak pixel detection, it is determined from the density relationship with surrounding pixels whether or not the target pixel is an extreme point indicating a peak or valley of density change. When the density level of the central pixel is higher or lower than all other density levels in the block composed of M × M pixels, it is determined whether or not it is an extreme point as shown in Expression (2) or Expression (3). . The peak pixel detecting means (3 × 3) 400 detects the peak pixel by the expression (2), and the peak pixel detecting means (5 × 5) detects the peak pixel by the expression (3). 401.
When M = 3 (FIG. 8C),
| 2m0−m1−m8 | ≧ ΔmTH and
| 2m0−m2−m7 | ≧ ΔmTH and
| 2m0-m3-m6 | ≧ ΔmTH and
| 2m0-m4-m5 | ≧ ΔmTH (Formula 2)
When M = 5 (FIG. 8D),
| 2m0−m1−m24 | ≧ ΔmTH and
| 2m0−m7−m18 | ≧ ΔmTH and
| 2m0−m3−m22 | ≧ ΔmTH and
| 2m0−m8−m17 | ≧ ΔmTH and
| 2m0−m5-m20 | ≧ ΔmTH and
| 2m0−m9−m16 | ≧ ΔmTH and
| 2m0−m11−m14 | ≧ ΔmTH and
| 2m0−m12−m13 | ≧ ΔmTH (Formula 3)
That is, the center pixel is detected as a peak when the average value of the two pixel levels located symmetrically with the center pixel in between and the absolute value of the density difference between the center pixels are larger than the threshold value ΔmTH. Peak pixel detection may be performed for each of the RGB signals, but in the case of simplification, peak detection is performed for the G signal. Then, based on the peak pixel information, it is determined whether the area is a halftone dot area. If either one of the two peak pixel detection means 400 and 401 is detected by the OR circuit 402 as a peak pixel, it is determined as a peak pixel, and the blocking means 403 determines a peak pixel for each block of 4 × 4 pixels. If there is even one, it is determined as an active block, and the density correction 404 means counts the active block in the 5 × 5 block centered on the target block, and if the count value is a predetermined number or more, the target block is a halftone dot. Finally, the expansion means 405 performs expansion processing in 3 × 3 blocks, and if even one halftone dot block exists, the target block is set as a halftone dot region.

  The determination result of the attribute determination unit 40 is applied to the filter 13 and the toner save processing unit 16. If the result of the attribute determination is a halftone dot, the filter 13 performs a process of slightly smoothing and weakening edge enhancement slightly than the non-halftone dot portion in order to suppress moire.

  A description will be given of toner save processing according to the present exemplary embodiment when the user designates the toner save mode and (2) a character document or (4) a map document is selected (implemented when another document type is selected). The same toner save process as in Example 1 is performed).

  In this embodiment, as shown in FIG. 9, toner save γ according to the attribute determination result and the edge detection result is applied. Since the CMY signal is the same as that of the first embodiment, the description thereof is omitted. Since the toner save γ of γ3 is applied to the K signal if it is a halftone dot, the density is preserved at the edge portion and non-edge portion (= inside of the character) of the black character except the low density gray character. For halftone characters only, it is usually necessary to provide contrast with the background, so the appearance rate of low density gray characters is even lower than on white ground. Then, in the case of a character image on a gray halftone dot, a toner save process with a value of 50% is performed on the halftone dot portion that is the background. In addition, since γ1 toner save γ is applied to non-halftone dots, not only high-density black characters but also low-density gray characters are conserved in the density to the inside of the characters.

  As described above, according to the present embodiment, in addition to the effects of the first embodiment, black characters on non-halftone dots can be reproduced with high image quality even with low density characters.

Example 3:
The third embodiment is another embodiment of the toner save processing unit 16 that uses the attribute determination result of the attribute determination unit 40.

  FIG. 10A shows a configuration of the attribute determination unit 40 of the third embodiment. The attribute determination means 40 of the present embodiment is composed of a halftone dot separation means 41 and a white background separation means 42. The white background determination means 43 is “white background” if it is non-halftone and white background, and “non- It is determined as “white background”.

  FIG. 10B shows the configuration of the white background separating means 42. The binarization unit 406 binarizes the G signal into white / non-white pixels with a predetermined threshold, and the white pixel detection unit 407 prepares in advance a local two-dimensional pattern formed by the binarization signal. A white background pixel is detected by comparison with a white background pixel pattern. As an example of the pattern to be prepared, the simplest is that all the pixels in the 5 × 5 mask are white pixels, and it is assumed that the target pixel is a white background pixel when this condition is satisfied. Next, the expansion unit 408 determines that the target pixel or the target block is a temporary white background neighboring region when one or more white background pixels detected by the white pixel detection unit 407 exist in a block of a predetermined size centered on the target pixel. judge. Next, the correcting unit 409 determines that the pixel of interest is a white background when there is a temporary white background area in both the left and right or up and down directions of the pixel of interest.

  An example of the correction process will be given. As shown in FIG. 10C, when the pixel A that is M pixels to the left and the pixel B that is M pixels to the right are both in the vicinity of the temporary white background, or the pixel is M pixels upward from the pixel of interest. When the pixel C and the pixel D that is M pixels below are both in the temporary white background region, the pixel of interest is determined to be a white background.

  In order to determine the white background with reference to the temporary white background vicinity in both the left and right or up and down directions, characters with a thickness exceeding a predetermined line width, solid images or pattern images having a predetermined width are non-white, including the edge portion. The background is determined. By adjusting the size of M, the boundary between the line width determined as a white background and the line width determined as a non-white background can be changed.

  The determination result of the attribute determination unit 40 is applied to the filter 13 and the toner save processing unit 16. If the result of the attribute determination is a non-white background, the filter performs a process of slightly smoothing and weakening edge enhancement slightly than the non-halftone part in order to suppress moire.

  A toner save process according to the present embodiment when the user designates the toner save mode and (2) a text document or (4) a map document is selected will be described.

  In this embodiment, as shown in FIG. 11, toner save γ according to the attribute determination result and the edge detection result is applied. Since the toner save γ of γ3 is applied to the K signal if it is a non-white background, the density is preserved at the edge portion and non-edge portion (= inside of the character) of the black character excluding the low density gray character. In the case of a character image on a gray dot, a toner save process with a value of 50% is applied to the halftone dot portion that is the background. Further, since toner save γ of γ1 is applied to a white background, not only high-density black characters but also low-density gray characters are stored in the density to the inside of the characters.

  The difference between the third embodiment and the second embodiment is that the white background is determined using the white background separating means 42 in the third embodiment, so that the characters having a thickness exceeding a predetermined line width or a solid image having a predetermined width are used. And the pattern image is determined as a non-white background including the edge portion, and the toner save γ of γ3 is applied. As a result, the toner saving process becomes effective for a low-density bold text, solid image, or continuous tone image (silver salt photograph), and the toner reduction effect is improved.

  Even when the user selects (2) a text document or (4) a map document, it cannot be said that there is no solid image or continuous tone image. In addition to characters and maps, the above toner save processing may be applied when (1) a character / photo original is selected.

  As described above, according to the present embodiment, in addition to the effects of the first embodiment, a black character having a predetermined line width or less on a white ground can be reproduced with high image quality even with a low-density character regardless of the density. In addition, the toner saving process is effective for a low-density bold text, solid image, or continuous tone image (silver salt photograph), and the toner reduction effect is improved. Further, even when the toner save process of the present embodiment is applied to an image including a pattern, there is little discomfort in image quality.

Example 4:
In the above-described embodiment, the edge detection result is not substantially used in the case of the achromatic color, and the same toner save γ is applied to the edge and the non-edge. However, the edge detection result is also used in the case of the achromatic color. Also good.

  In this embodiment, as shown in FIG. 12A, toner save γ corresponding to the edge detection result is applied to the K signal. By applying the toner save γ of γ1 at the edge and the toner save γ3 of γ3 at the non-edge portion to the K signal, the density of the edge portion is preserved in the low density gray character, and the non-edge portion (= character (Inside), toner save processing is performed by 50% reduction. Since the density of the edge portion is preserved, the readability of the low density gray character is maintained. As for the high-density black characters, as in the above-described embodiment, the density is stored up to the inside of the characters, and high-quality character image quality can be maintained.

  As described above, according to the present embodiment, in addition to the effects of the above-described embodiment, the density of the edge portion is always preserved (regardless of halftone dots / non-halftone dots, white background / non-white background) in low density gray characters. It is effective in maintaining the legibility of low-density gray characters.

Example 5:
In the above-described embodiment, as the toner save γ3, in the high density portion, the one that stores the density in the same manner as the toner save γ1 is used to reproduce the inside of the black character at the same level as the edge. This is not a big problem as long as the process of applying toner save γ3 is performed on a text document or (4) a map document, but in the case of a design philosophy with a little emphasis on a pattern or other documents (for example, (1 When the toner saving process using the toner save γ3 is similarly applied to (character / photo original), the density of the achromatic high density portion in the pattern is stored, which is not preferable in terms of image quality and a toner reduction effect.

  In this embodiment, therefore, the toner save γ3 ′ shown in FIG. 12B is used in the toner save process shown in FIG. Since the density is slightly lowered inside the black character, a density difference from the edge is generated. However, if the density is not lowered too much, the degree of image quality deterioration can be reduced. Further, since the toner saving process is performed to some extent at the achromatic high density portion in the pattern, the image quality is less uncomfortable and the toner reduction effect is enhanced.

  As described above, according to the present embodiment, in addition to the effects of the above-described embodiments, high-quality reproduction of high-density black characters, which is inherently in a trade-off relationship, an uncomfortable feeling suppression and toner reduction effect at an achromatic high-density portion in a pattern Can be achieved in a balanced manner, and a high-quality toner save image can be output in total.

Example 6:
In the above-described embodiment, an example in which toner save processing using toner save γ3 or 3 ′ is mainly performed on (2) a character original or (4) a map original is described. There is a device having a function of selecting and specifying an image quality mode such as character priority and picture priority. In such an apparatus, it is also effective to perform toner save γ using toner save γ3 or 3 ′ in accordance with the image quality mode.

  (1) In the case of a character / photo original, the image quality mode can be selected in three stages: character priority, middle (both are equally important), and picture quality. In the case of character priority, (2) the process using toner save γ3 is performed as in the case of the character document, and in the middle case, the process using toner save γ3 'of Example 5 is performed. In the case of design priority, toner save processing is performed that does not use toner saves γ3 and 3 'as shown in FIG.

  As described above, according to the present embodiment, even in an apparatus having a function of selecting and specifying an image quality mode, particularly when characters are prioritized, high-quality reproduction of black characters, maintaining readability of color characters, improving the toner reduction effect of character background portions, etc. It can be compatible.

  The present invention also supplies a storage medium storing software program codes for realizing the processing procedures and functions of the above-described embodiments to a system or apparatus, and a computer (CPU or MPU) of the system or apparatus stores the storage medium. This can also be achieved by reading and executing the program code stored in. In this case, the program code itself read from the storage medium realizes the processing procedures and functions of the above-described embodiment. As a storage medium for supplying the program code, for example, a flexible disk, a hard disk, an optical disk, a magneto-optical disk, a magnetic tape, a nonvolatile memory card, a ROM, or the like can be used. Further, by executing the program code read by the computer, not only the processing procedures and functions of the above-described embodiments are realized, but also an OS (operating system) running on the computer based on the instruction of the program code. ) Etc. perform part or all of the actual processing, and the processing procedures and functions of the above-described embodiments are realized by the processing. Further, after the program code read from the storage medium is written into a memory provided in a function expansion board inserted into the computer or a function expansion unit connected to the computer, the function expansion is performed based on the instruction of the program code. This includes the case where the CPU or the like provided in the board or the function expansion unit performs part or all of the actual processing, and the processing procedures and functions of the above-described embodiments are realized by the processing.

The structure of Example 1 of this invention is shown. A black generation LUT is shown. The structure of an edge detection means is shown. The structure of an edge amount detection means is shown. The result of the edge detection in a character edge is shown. FIG. 6 is a diagram illustrating toner save processing according to the first exemplary embodiment. The structure of Example 2 of this invention is shown. The structure of the attribute determination means of Example 2 is shown. FIG. 10 is a diagram illustrating toner save processing according to the second exemplary embodiment. The structure of the attribute determination means of Example 3 is shown. FIG. 10 is a diagram illustrating toner save processing according to a third exemplary embodiment. FIG. 10 is a diagram illustrating toner save processing in Examples 4 to 6.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Scanner 11 Scanner gamma correction means 12 Scanner color correction means 13 Filter 14 Printer color correction means 15 Black processing means 16 Toner save processing means 17 Printer gamma correction means 18 Pseudo halftone processing means 19 Printer 20 Edge detection means 30 Operation panel

Claims (12)

The image including an achromatic signal and chromatic signal, and an output mode without saving color material consumption, the image processing apparatus having a toner save mode to save color material consumption, to detect the edge of the image When the edge detection means and the toner save mode are set, the output value with respect to the input value is reduced by a predetermined ratio when the input value of the achromatic color signal is equal to or less than a first threshold with respect to the achromatic color signal. When the input value exceeds the first threshold value and is equal to or less than the second threshold value, the output value is reduced by the second threshold value by reducing the ratio of reducing the output value as the input value increases. Applying a non-linear characteristic that converts the input value to an output value so that the input value becomes equal to the output value when the input value exceeds the second threshold, and the chromatic signal Against the edge of Applying a linear first characteristic that converts the input value into an output value so that the input value and the output value of the chromatic color signal are equal, and the non-edge of the chromatic color signal An image having toner save processing means for performing toner save processing by applying a linear second characteristic for converting the input value to the output value by reducing the output value with respect to the input value at a predetermined ratio. Processing equipment. The image including an achromatic signal and chromatic signal, and an output mode without saving color material consumption, the image processing apparatus having a toner save mode to save color material consumption, to detect the edge of the image The nonlinear characteristic according to claim 1 , wherein an edge detection unit, an attribute determination unit that determines a halftone dot region of the image, and the halftone dot region of the achromatic signal when the toner save mode is set. The linear first characteristic according to claim 1 is applied to a non-halftone area of the achromatic signal, and the linear first characteristic according to claim 1 is applied to an edge of the chromatic signal. And a toner save processing means for executing toner save processing by applying the second linear characteristic according to claim 1 to the non-edge of the chromatic color signal. Processing equipment. The image including an achromatic signal and chromatic signal, and an output mode without saving color material consumption, the image processing apparatus having a toner save mode to save color material consumption, to detect the edge of the image The nonlinear characteristic according to claim 1 is applied to a non-white background region of the achromatic signal when an edge detection unit, an attribute determination unit that determines a white background region of the image, and the toner save mode are set. The linear first characteristic according to claim 1 is applied to a white background region of the achromatic color signal, and the linear first characteristic according to claim 1 is applied to an edge of the chromatic color signal. An image processing apparatus, comprising: a toner save processing unit that applies toner linear processing to the non-edge of the chromatic color signal by applying the linear second characteristic according to claim 1 . The image including an achromatic signal and chromatic signal, and an output mode without saving color material consumption, the image processing apparatus having a toner save mode to save color material consumption, to detect the edge of the image Edge detection means, means for determining or specifying the type of a document including a character document, a map document, and a character photo document, and when the toner save mode is set, the document type is a character document or a map document In addition, the nonlinear characteristic according to claim 1 is applied to the achromatic signal, the linear first characteristic according to claim 1 is applied to an edge of the chromatic signal, and the chromatic color is applied. The linear second characteristic according to claim 1 is applied to a non-edge of a signal, and when the type of the original is a character photo original, the edges of the achromatic signal and the chromatic signal are Line according to claim 1 Applying a first characteristic, the relative non-edge of the achromatic signal and chromatic signal, the toner save processing means for executing a toner save processing by applying a linear second characteristic of claim 1, wherein An image processing apparatus comprising: The image including an achromatic signal and chromatic signal, and an output mode without saving color material consumption, the image processing apparatus having a toner save mode to save color material consumption, to detect the edge of the image An edge detection unit, an image output mode designating unit for designating an image output mode of character priority or design priority, and the achromatic signal when the image output mode is character priority when the toner save mode is set. On the other hand, the nonlinear characteristic according to claim 1 is applied, the first linear characteristic according to claim 1 is applied to the edge of the chromatic signal, and the non-edge of the chromatic signal is applied. Then, when the linear second characteristic according to claim 1 is applied and the image output mode is a pattern priority, the linear characteristic according to claim 1 is applied to an edge of the achromatic signal and the chromatic signal. First special Applying the said achromatic signal for non-edge chromatic signal, and wherein a toner save processing means for executing a toner save processing by applying a linear second characteristic of claim 1, wherein An image processing apparatus. The image including an achromatic signal and chromatic signal, and an output mode without saving color material consumption, the image processing method including a toner save mode for saving the color material consumption, to detect the edge of the image When the edge detection step and the toner save mode are set, the output value with respect to the input value is reduced by a predetermined ratio when the input value of the achromatic color signal is equal to or less than a first threshold with respect to the achromatic color signal. When the input value exceeds the first threshold value and is equal to or less than the second threshold value, the output value is reduced by the second threshold value by reducing the ratio of reducing the output value as the input value increases. Applying a non-linear characteristic that converts the input value to an output value so that the input value becomes equal to the output value when the input value exceeds the second threshold, and the chromatic signal Against the edge of Applying a linear first characteristic that converts the input value into an output value so that the input value and the output value of the chromatic color signal are equal, and the non-edge of the chromatic color signal An image comprising: a toner save processing step of executing a toner save process by applying a second linear characteristic for converting the input value into an output value by reducing the output value with respect to the input value at a predetermined ratio. Processing method. The image including an achromatic signal and chromatic signal, and an output mode without saving color material consumption, the image processing method including a toner save mode for saving the color material consumption, to detect the edge of the image The nonlinear characteristic according to claim 1 , wherein an edge detection step, an attribute determination step for determining a halftone dot region of the image, and the halftone dot region of the achromatic signal when the toner save mode is set. The linear first characteristic according to claim 1 is applied to a non-halftone area of the achromatic signal, and the linear first characteristic according to claim 1 is applied to an edge of the chromatic signal. And a toner saving process for executing toner saving processing by applying the second linear characteristic according to claim 1 to the non-edge of the chromatic color signal. Processing method. The image including an achromatic signal and chromatic signal, and an output mode without saving color material consumption, the image processing method including a toner save mode for saving the color material consumption, to detect the edge of the image The nonlinear characteristic according to claim 1 is applied to a non-white background region of the achromatic signal when an edge detection step, an attribute determination step for determining a white background region of the image, and the toner save mode are set. The linear first characteristic according to claim 1 is applied to a white background region of the achromatic color signal, and the linear first characteristic according to claim 1 is applied to an edge of the chromatic color signal. An image processing method comprising: a toner save process step of applying a toner save process by applying the second linear characteristic according to claim 1 to a non-edge of the chromatic color signal . The image including an achromatic signal and chromatic signal, and an output mode without saving color material consumption, the image processing method including a toner save mode for saving the color material consumption, to detect the edge of the image An edge detection step, a step of determining or specifying the type of a document including a character document, a map document, and a character photo document; and when the toner save mode is set, the document type is a character document or a map document In addition, the nonlinear characteristic according to claim 1 is applied to the achromatic signal, the linear first characteristic according to claim 1 is applied to an edge of the chromatic signal, and the chromatic color is applied. The linear second characteristic according to claim 1 is applied to a non-edge of a signal, and when the type of the original is a character photo original, the edges of the achromatic signal and the chromatic signal are Line according to claim 1 Applying a first characteristic, the relative non-edge of the achromatic signal and chromatic signal, the toner save processing step of executing the toner saving processing by applying a linear second characteristic of claim 1, wherein An image processing method comprising: The image including an achromatic signal and chromatic signal, and an output mode without saving color material consumption, the image processing method including a toner save mode for saving the color material consumption, to detect the edge of the image An edge detection step, an image output mode designating step for designating an image output mode with character priority or design priority, and the achromatic signal when the image output mode is character priority when the toner save mode is set. On the other hand, the nonlinear characteristic according to claim 1 is applied, the first linear characteristic according to claim 1 is applied to the edge of the chromatic signal, and the non-edge of the chromatic signal is applied. Then, when the linear second characteristic according to claim 1 is applied and the image output mode is a pattern priority, the linear characteristic according to claim 1 is applied to an edge of the achromatic signal and the chromatic signal. First special Applying the said achromatic signal for non-edge chromatic signal, and wherein a toner save processing step of executing the toner saving processing by applying a linear second characteristic of claim 1, wherein Image processing method. The program for making a computer implement | achieve the image processing method of any one of Claims 6 thru | or 10 . A computer-readable recording medium a program for implementing the image processing method according to the computer in any one of claims 6 to 10.

Images