WO2003096675A1 - Dispositif et procede de creation d'image couleur - Google Patents

Dispositif et procede de creation d'image couleur Download PDF

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Publication number
WO2003096675A1
WO2003096675A1 PCT/JP2002/004651 JP0204651W WO03096675A1 WO 2003096675 A1 WO2003096675 A1 WO 2003096675A1 JP 0204651 W JP0204651 W JP 0204651W WO 03096675 A1 WO03096675 A1 WO 03096675A1
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WIPO (PCT)
Prior art keywords
color
pixel
smoothing
correction
density value
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PCT/JP2002/004651
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English (en)
Japanese (ja)
Inventor
Hiroshi Nou
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Fuji Xerox Co., Ltd.
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Publication date
Application filed by Fuji Xerox Co., Ltd. filed Critical Fuji Xerox Co., Ltd.
Priority to PCT/JP2002/004651 priority Critical patent/WO2003096675A1/fr
Priority to JP2004508533A priority patent/JP4135713B2/ja
Publication of WO2003096675A1 publication Critical patent/WO2003096675A1/fr

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/40—Picture signal circuits
    • H04N1/409—Edge or detail enhancement; Noise or error suppression

Definitions

  • the present invention relates to a color image forming apparatus and a color image forming method used in a color printer or the like which is an output device of color image data generated by a computer or the like, and particularly to a character and line drawing method.
  • the present invention relates to a color image forming apparatus and a color image forming method for preventing jaggedness due to pixels (dots) generated during image formation, that is, edge false color generated after smoothing processing which is image quality improvement processing for making jaggy less noticeable.
  • FIG. 4 is a block diagram showing a configuration example of a conventional laser printer.
  • the laser printer shown in FIG. 4 includes a main unit 1, an image memory 12, an image developing unit 13, a control circuit 14, and an optical modulation signal generation circuit 15.
  • the main unit 1 includes an optical unit 2 and an image forming unit 11.
  • the optical unit 2 includes a laser 3, a polygon mirror 4, a mirror motor 5, and a beam detector 6.
  • the image forming unit 11 includes a photosensitive drum 7, a developing unit 8, a folding mirror 9, and a transfer port 10.
  • the laser 3 outputs a laser beam according to the optical modulation signal from the optical modulation signal generation circuit 15.
  • the polygon mirror 4 is driven to rotate by a mirror motor 5 and deflects so as to repeatedly scan the laser beam.
  • the beam detector 6 detects the start of scanning of the laser beam to be scanned, and outputs an optical scanning timing signal to the control circuit 14.
  • the surface of the photosensitive drum 7 is charged by a charger (not shown). Thereafter, the surface of the photosensitive drum 7 is irradiated with a laser beam via the folding mirror 9.
  • the laser 3 is modulated in synchronization with the scanning of the laser beam and the rotation of the photosensitive drum 7.
  • the surface of the photosensitive drum 7 is irradiated with an optical image corresponding to an image to be printed. Exposure The electrostatic charge charged on the surface of the ram 7 decreases according to the irradiation amount of the laser beam. At this time, an electrostatic latent image is formed on the surface of the photosensitive drum 7.
  • the toner adheres according to the electrostatic latent image on the surface of the photosensitive drum 7 and is visualized.
  • the conveyed paper or the like is brought into contact with the surface of the photosensitive drum 7 on which the toner image has been formed, and the transfer roller 10 transfers the toner image to the paper.
  • Printing is completed when the transferred toner image is fixed on paper or the like by a fixing device (not shown). After the transfer of the toner image, the surface of the photosensitive drum is cleaned, charged again, and the above process is repeated.
  • print data input from a computer system or the like is input to the image developing unit 13.
  • the control circuit 14 outputs the control signal generated in synchronization with the optical scanning timing signal to the image developing unit 13 and the optical modulation signal generation circuit 15.
  • the control cook signal is a signal indicating print timing for each pixel.
  • the image developing unit 13 sequentially develops the print data into image data to be actually printed in accordance with the control clock signal, and outputs the image data to the image memory 12.
  • the image memory 12 stores image data.
  • the image memory 12 is called a bitmap memory. In the case of binary image data, one bit represents one pixel to be printed, and in the case of multi-valued image data, a density value consisting of several bits. Represents one pixel to be printed.
  • the optical modulation signal generation circuit 15 sequentially reads out the image data stored in the image memory 12 according to the control clock signal, generates an optical modulation signal according to the image data, and sequentially converts the optical modulation signal according to the control clock signal. To the laser 3.
  • jaggies generated in printing of characters and line drawings are automatically determined from image data developed on the image memory 12 and data having a higher resolution than the input image data. After that, some smoothing processing is used to make jaggies less noticeable.
  • FIG. 5 is a diagram showing an example of a smoothing process of binary image data.
  • the vertical axis represents lines in dot units
  • the horizontal axis represents pixel positions in lines in dot units.
  • the image memory (image data memo) I) It is assumed that there is a vertical line shifted by one dot in the image data stored in 12. This deviated part is jaggy.
  • jaggy is determined by pattern matching including neighboring pixels.
  • the output timing of the corrected optical modulation signal is adjusted as shown in FIG. 5 (b).
  • FIG. 6 is a block diagram showing a configuration example of a conventional binary image forming apparatus that performs a smoothing process of binary image data.
  • the optical modulation signal generation circuit 15 shown in FIG. 6 includes an image memory reading unit 16 and a smoothing circuit 17.
  • the smoothing circuit 17 includes a line buffer 18, an evaluation window extraction unit 21, and a correction unit 22.
  • the same reference numerals as those in FIG. 4 denote the same or corresponding objects as those shown in FIG. 4, and a description thereof will be omitted.
  • Binary image data is developed in the image memory 12 by an image developing unit (not shown).
  • the image memory reading section 16 reads image data several lines before being exposed by the laser 3 from the image memory 12 and transfers the image data to the line buffer 18.
  • the line buffer 18 is composed of a shift register, and holds image data for several lines before and after exposure.
  • the evaluation window extraction unit 21 generates a rectangular area (hereinafter referred to as an evaluation window) centered on one pixel (hereinafter referred to as a pixel of interest) 20 to be smoothed in the image data stored in the line buffer 18. It extracts the pattern of the pixels in 19 and outputs it to the correction unit 22 as an extracted pattern arrangement signal.
  • the correction unit 22 has a look-up table (LUT: Look Up Table) in which a plurality of pairs of a pattern that can be taken by a pixel in the evaluation window and a smoothing result of a target pixel according to the pattern are stored in advance.
  • the pattern stored in the lookup table is compared with the extracted pattern arrangement signal, and the matched pattern is handled. Is selected as the correction data of the pixel of interest stored as such. If no correction is required, an optical modulation signal corresponding to the original data of the pixel of interest is output to the optical unit 2, and if correction is required, an optical modulation signal corresponding to the correction data of the pixel of interest is output. Is output to the optical unit 2.
  • LUT Look Up Table
  • FIG. 7 is a diagram showing an example of a smoothing process for an extracted pattern arrangement signal.
  • the vertical axis represents the line in dot units
  • the horizontal axis represents the pixel position in the line in dot units.
  • the smoothing circuit 17 shown in Fig. 6 outputs the optical modulation signal at the position of the target pixel when the pixels at the position corresponding to the target pixel are sequentially printed in synchronization with the control clock signal.
  • the control clock signal for controlling the operation timing is generated by a control clock signal generation unit 23 provided in the control circuit 14.
  • the control clock signal generation section 23 in the control circuit 14 generates a control clock signal in synchronization with the optical scanning timing signal output from the optical section 2 and outputs the control clock signal to the optical modulation signal generation circuit 15. Power.
  • the above description is an example of the case where the pixel is corrected at twice the resolution in the main scanning direction, but the same applies to the case where the correction is performed at a resolution of three times or more.
  • a printing apparatus not only a binary printing apparatus for black and white but also a multi-value printing apparatus capable of expressing pixels having an intermediate density is provided.
  • a laser printer as shown in FIG. 4, by controlling the light emission amount or the light emission time of the laser 3 in the optical unit 2, the size of the pixel formed in the image forming unit 11 is changed, and the equivalent is obtained. The density of the pixel to be printed is changed.
  • FIG. 8 is a block diagram showing a configuration example of a multilevel laser printer.
  • the optical modulation signal generation circuit 32 shown in FIG. 8 includes an image memory reading unit 33 and a digital-to-analog conversion unit 34.
  • the same reference numerals as those in FIG. 4 denote the same or corresponding objects as those shown in FIG. 4, and a description thereof will be omitted.
  • the image memory 31 multivalued image data having a density is developed by an image developing unit (not shown).
  • control clock signal generation unit 36 in the control circuit 35 generates a control clock signal in synchronization with the optical scanning timing signal output from the optical unit 2 and sends the control clock signal to the optical modulation signal generation circuit 32.
  • the image memory reading unit 33 sequentially reads the multi-valued image data from the image memory 31 in accordance with the control signal, and outputs the multi-valued image data to the DZA conversion unit 34.
  • the 0/8 conversion unit 34 converts the digital density value in the multi-valued image data into an optical modulation signal representing analog intensity, and sequentially outputs the optical modulation signal to the optical unit 2 according to a control clock signal.
  • FIG. 9 is a diagram showing an example of the smoothing processing of the quaternary image data.
  • the vertical axis represents lines in dot units, and the horizontal axis represents pixel positions in lines in dot units.
  • FIG. 9 (a) shows an example of a pattern of quaternary image data on the image memory (image data memory), and
  • FIG. 9 (b) shows an optical modulation signal when performing multi-value printing.
  • Fig. 9 (c) shows the print result.
  • D is an integer that satisfies the condition 2 D — i CSD.
  • the conventional smoothing circuit is directly applied to multivalued image data smoothing processing in a multivalued printing device, the size of the lookup table required becomes very large, and the table data is also created using the pixel pattern. It becomes complicated and difficult to create a combination of these and their concentrations, and this is not practical.
  • FIG. 10 is a block diagram showing a configuration example of a conventional multilevel image forming apparatus for performing a smoothing process of multilevel image data.
  • the optical modulation signal generation circuit 42 shown in FIG. 10 includes an image memory reading section 43, a smoothing circuit 44, and a 0 conversion section 53.
  • the smoothing circuit 44 includes a density decomposition section 45, a plane 1 correction section 46a, a plane 2 correction section 46b, a plane 3 correction section 46c, and a correction value synthesis section 52.
  • each of the plane 1 correction unit 46a to the plane 3 correction unit 46c includes a line buffer 47, an evaluation window extraction unit 50, and a correction unit 51.
  • the same reference numerals as those in FIG. 4 denote the same or corresponding objects as those shown in FIG. 4, and a description thereof will be omitted.
  • the laser printer including the optical modulation signal generation circuit 42 shown in FIG. 10 performs printing in four gradations including white and black in pixel units.
  • the image memory 41 is composed of a 2-bit image memory.
  • the image memory 41 is printed in advance by an image expansion unit (not shown). Multi-valued image data is developed in a possible state. Also, since three gradations can be expressed in pixel units except for white, three density planes are prepared. Here, the density of the pixel is represented by a numerical value from 0 to 3, and the larger the numerical value, the higher the density. That is, the density 0 corresponds to white and the density 3 corresponds to black.
  • the control clock signal generation section 55 in the control circuit 54 generates a control clock signal in synchronization with the optical scanning timing signal output from the optical section 2 and outputs it to the optical modulation signal generation circuit 42. I do.
  • the optical modulation signal generation circuit 42 is controlled by a control clock signal so as to output an optical modulation signal in synchronization with the progress of image writing in the main body 1.
  • the image memory reading unit 43 outputs the multi-valued image data read from the image memory 41 to the density decomposing unit 45.
  • the density decomposing unit 45 distributes and outputs the binarized pixel data to the plane 1 correction unit 46a to the plane 3 correction unit 46c according to a predetermined distribution rule based on the density of the multivalued image data.
  • pixel data is density-decomposed into planes for each pixel density on the image memory 41 and distributed.
  • the pixel data of density 1 in the image memory 41 is sent to the plane 1 correction unit 46a
  • the pixel data of density 2 is sent to the plane 2 correction unit 46b
  • the pixel data of density 3 is output to the plane 3 correction unit 4 6c each.
  • the plane 1 correction unit 46a to the plane 3 correction unit 46c perform smoothing processing on the input pixel data in the correction unit 51, and output a correction value of a corresponding level.
  • binarized pixel data is input to each of the plane 1 correction unit 46a to the plane 3 correction unit 46c.
  • each of the plane 1 correction unit 46a to the plane 3 correction unit 46c has the same configuration as the smoothing circuit in the conventional binary image forming apparatus, and the same correction rule can be applied. That is, the smoothing circuit 17 shown in FIG. 6 can be used as it is.
  • the correction values output from each of the plane 1 correction unit 46 a to the plane 3 correction unit 46 c are synthesized by the correction value synthesis unit 52 according to a predetermined synthesis rule, and output to the D / A conversion unit 53.
  • a predetermined synthesis rule used by the correction value synthesis unit 52 for example, if a non-zero plane exists for the same pixel, The correction value of the plane with the highest density among the patterns is output with priority.
  • the D / A converter 53 converts the digital correction value into an optical modulation signal representing an analog intensity, and sequentially outputs the signal to the optical unit 2 according to a control clock signal.
  • FIG. 11 is a block diagram showing another example of the configuration of a conventional multi-value image forming apparatus that performs the following.
  • the optical modulation signal generation circuit 61 shown in FIG. 11 includes an image memory reading section 43, a smoothing circuit 62, and a D / A conversion section 53.
  • the smoothing circuit 62 includes a line buffer 47, an evaluation window extraction unit 50, a binarization processing unit 63, and a correction unit 64.
  • the same reference numerals as those in FIGS. 4 and 10 denote the same or corresponding objects as those shown in FIGS. 4 and 10, and a description thereof will be omitted.
  • the laser printer including the optical modulation signal generation circuit 61 shown in FIG. 11 performs printing in units of pixels, for example, at 16 gradations. Therefore, the image memory 41 comprises a 4-bit image memory.
  • the pixel data in the evaluation window cut out by the evaluation window extraction unit 50 is subjected to a binarization process by comparison with adjacent pixels in a binarization processing unit 63. Are output to the correction unit 64.
  • the correction unit 64 compares the pixel data in the binarized evaluation window with the look-up table to generate a binary LUT correction value, and finally, based on the original data, this LUT correction value Multi-value processing is performed to restore the value to multi-value, a multi-value correction value is generated, and output to the DZA converter 53.
  • the conversion unit 53 converts the digital multi-value correction value into an optical modulation signal representing analog intensity, and sequentially outputs the modulated signal to the optical unit 2 according to the control clock signal. Power.
  • FIG. 12 is a flowchart showing an example of the binarization processing, the LUT collation processing, and the multi-value processing.
  • the evaluation window size is 3 ⁇ 3 and the main scanning direction is divided into two.
  • FIG. 13 is a diagram showing a process from extraction of an evaluation window to multi-value processing.
  • d1 indicates the density value of the target pixel
  • d2 indicates the density value of the adjacent pixel located to the left of the target pixel
  • d3 indicates the density value of the adjacent pixel located to the right of the target pixel.
  • D1 indicates the density value of the target pixel subjected to the binarizing processing.
  • the density value of the left part is D1a
  • the density value of the right part is D1b.
  • the evaluation window extracting unit 50 extracts the pixel data in the evaluation window 48 from the pixel data held in the line buffer 47 (S1).
  • the binarization processing section 63 performs binarization processing (S 2) on the pixel data in the evaluation window 48.
  • dmax indicates max (d2, d3)
  • dmin indicates min (d2, d3) (S21).
  • step S22 it is determined whether or not the force satisfies dmax-d1> th. If the determination result is Yes, the process proceeds to step S4 described below.
  • th is a threshold value, for example, 2.
  • the decision result in the step S22 is No
  • a step S23 it is decided whether or not d1 ⁇ dmin> th, and if the decision result is Yes, a step S5 described later is performed. Move to.
  • the decision result in the step S23 is No, the process shifts to a step S31 in a step S3 described later.
  • step S4 an evaluation window A shown in FIG. 14A is performed.
  • step S43 it is determined whether or not dl + t hZ2> d (x, y). Set. If the decision result in the step S43 is Yes, the step S44 sets 0 to D (X, y). On the other hand, if the decision result in the step S43 is No, the step S45 sets 1 to D (X, y). After step S44 or step S45, step S46 outputs X, step S47 outputs y, and the process returns to the process shown in FIG. 12, and proceeds to the process of step S6.
  • step S5 an evaluation window binarization process B shown in FIG. 14 (b) is performed.
  • step S53 it is determined whether or not the force is d l ⁇ t hZ2> d (x, y). If the decision result in the step S53 is Yes, the step S54 sets 0 to D (x, y). On the other hand, if the decision result in the step S53 is No, the step S55 sets 1 to D (x, y). After step S54 or step S55, step S56 outputs X, step S57 outputs y, and the process returns to the process shown in FIG. 12, and proceeds to the process of step S6.
  • FIG. 15 is a diagram showing the result of the binarization process.
  • the pixel data in the evaluation window ⁇ ⁇ shown in FIG. 15 is binarized according to the above-described binarization process, resulting in a binarization evaluation window.
  • step S6 the correction unit 64 performs a LUT collation process (S6) for collating the result of the binarization process with the lookup table.
  • step S7 it is determined whether there is a matching pattern as a result of the LUT matching process. If the decision result in the step S7 is No, the process shifts to a step S31 in a step S3 described later. On the other hand, if the decision result in the step S7 is Yes, the flow shifts to a step S32 in a step S3 described later.
  • the correction unit 64 performs a multi-value processing (S3).
  • the multi-value processing is the same as the conventional method of correcting an optical modulation signal in FIGS. 6 and 7, but the correction data in FIGS. 6 and 7 are binary data, so the multi-value processing is performed again. Convert to a value.
  • the multi-value processing there are two methods, for example, a simple replacement processing shown in FIG. 16 and an averaging processing shown in FIG. In each multi-value processing, the simple replacement processing The averaging process has a feature that the edge after correction becomes smooth while the edge remains sharp.
  • FIG. 18 is a diagram showing a configuration example of a color laser printer using the conventional multi-level image forming apparatus shown in FIG. As shown in FIG. 18, this color laser printer has four image memories 41a to 41d, four optical modulation signal generation circuits 61a to 61d, and four optical units 2. a to 2d, four image forming units 11a to lid, a control circuit 54, and an image developing unit 71.
  • Each of the optical modulation signal generation circuits 61a to 61d has the same configuration as the optical modulation signal generation circuit 61 shown in FIG.
  • the optical units 2a to 2d and the image forming units 11a to 11d have the same configuration as the optical unit 2 and the image forming unit 11 shown in FIG.
  • the image memory 41, the optical modulation signal generation circuit 61, the optical unit 2, and the image forming unit 11 are connected to each color plane, C (cyan), M (magenta), and ⁇ . (Yellow) and K (black) components.
  • C cyan
  • M magenta
  • ⁇ yellow
  • K black
  • the input print data is input to the image developing unit 71.
  • the image expansion unit 71 expands the print data into color image data, divides the color image data into multi-valued image data for each color plane, and sequentially converts the C component multi-valued image data into an image memory according to a control clock signal.
  • 4 1a multi-valued image data of M component to image memory 4 1b, multi-valued image data of Y component to image memory 4 1c, multi-valued image data of K component to image memory 4 1d
  • the multivalued image data of the C component in the image memory 41a is processed by the optical modulation signal generation circuit 61a, the optical unit 2a, and the image forming unit 11a.
  • the multi-valued image data of the M component in the image memory 41b is processed by the optical modulation signal generation circuit 61b, the optical unit 2b, and the image forming unit 11b, and the Y component in the image memory 41c is processed.
  • the multi-valued image data is processed by an optical modulation signal generation circuit 61c, an optical unit 2c, and an image forming unit 11c, and the K-component multi-valued image data in the image memory 41d is subjected to optical modulation.
  • the signal is processed by the signal generation circuit 61 d, the optical unit 2 d, and the image forming unit 11 d.
  • Each of the optical units 2 a to 2 d outputs an optical scanning timing signal to the control circuit 54.
  • Control times The path 54 controls the optical modulation signal generation circuits 61a to 61d.
  • the present invention has been made to solve such a problem, and it is not necessary to increase the size of a required lookup table.
  • the present invention relates to a color image forming apparatus for smoothing input color image data, wherein the color image data is divided into multi-valued image data representing density values for each color component.
  • Image storage means for storing multivalued image data representing density values for each color component; and extracting a pattern of a predetermined area including a target pixel to be smoothed among pixels in the multivalued image data.
  • An evaluation window extracting unit for each color component a binary process for representing the pattern as the presence or absence of a dot; a binarization processing unit for each color component; and a binarization process based on the binarized pattern.
  • the smoothing of the pixel of interest and the multi-valued result of the smoothing are performed, and the correction consisting of the binary shading, the smoothing, and the multi-leveling is enabled by an external instruction.
  • the corrected density value of the target pixel is output, and if the correction is invalidated by an external instruction, the density value of the target pixel before correction is output.
  • Correction means for example, a corrected color tone calculated from the corrected density values of all the color components, and a pre-correction color tone calculated from the uncorrected density values of all the color components, for example.
  • a color difference between the color tone and the color tone is calculated. If the color difference is within a predetermined range, the correction is made valid, and the color difference must be within a predetermined range. And determining means for making the correction invalid, and outputting the result of the determination as the instruction to the correcting means.
  • the determining unit includes: a corrected color element projected on the ab plane, the corrected color tone expressed in Lab space; and the corrected color element expressed in Lab space.
  • a color tone before correction is projected on an ab plane using a color element before correction, and the color difference is a distance between the color element after correction and the color element before correction. .
  • the binarization processing means may include a density value of the target pixel to be binarized, and a density value of at least one pixel adjacent to the target pixel. Values are compared, and the density value at the target pixel is binarized based on the result of the comparison.
  • the correction unit includes a look-up table in which a plurality of sets of a pattern that the region can take and a smoothing result of the target pixel corresponding to the pattern are stored in advance.
  • the pattern stored in the look-up table is compared with the pattern output by the evaluation window extracting means, and the target pixel stored in the look-up table corresponding to the matched pattern is compared.
  • the feature is to output the smoothing result. According to such a configuration, by using a binary look-up table, a small-scale circuit can be realized even when the number of gradations is increased.
  • a portion expressed as a dot present by the smoothing corrects the target pixel.
  • the previous density value, a portion expressed as no dot by the smoothing is converted into a density value of a pixel adjacent to the portion, and if the binarized target pixel has no dot, the smoothing is performed by the smoothing.
  • the portion indicated as having no dot is converted into a density value of the target pixel before correction, and the portion indicated as having a dot by the smoothing is converted into the density value of an adjacent pixel.
  • the portion represented as a dot by the smoothing corrects the target pixel.
  • the previous density value, the portion represented as no dot by the smoothing was converted into an intermediate value between the density value of the pixel adjacent to the portion and the density value of the pixel of interest before correction, and the binarization was performed.
  • the portion expressed as no dot by the smoothing is the density value before correction of the target pixel
  • the portion expressed as having a dot by the smoothing is a pixel adjacent to the portion. It is characterized in that it is converted into an intermediate value between the density value and the density value of the target pixel before correction.
  • the present invention also relates to a color image forming method for smoothing input color image data, wherein the color image data is divided into multi-valued image data representing a density value for each color component.
  • Multi-valued image data representing density values for each color component is stored, and a pattern of a predetermined area including a target pixel to be smoothed among pixels in the multi-valued image data is extracted for each of the color components. Is performed for each of the color components, and smoothing of the pixel of interest and multi-leveling of the result of the smoothing are performed based on the pattern obtained by performing the binary printing.
  • the corrected density value of the target pixel is output, and the correction is invalidated by an external instruction.
  • a process of outputting a density value before correction in the pixel of interest is performed for each color component, for example, a corrected density value calculated from the density values after correction in all the color components.
  • the corrected color tone expressed in a Lab space is projected on an ab plane, and the corrected color element is expressed in a Lab space.
  • the color difference is a distance between the color element after correction and the color element before correction by using a color element before correction projected on the ab plane of a color tone before correction. .
  • the binarization is performed by comparing a density value of a target pixel to be binarized with a density value of at least one pixel adjacent to the target pixel.
  • the method is characterized in that the density value at the target pixel is binarized based on the result of the comparison.
  • the smoothing is performed by using a look-up table in which a plurality of sets of a pattern that can be taken by the region and a smoothing result of the target pixel corresponding to the pattern are stored in advance. Comparing the pattern stored in the applet table with the pattern output by the evaluation window extracting means, and outputting a smoothing result of the pixel of interest stored in the look-up table corresponding to the matched pattern. It is a feature. Further, in the color image forming method according to the present invention, in the multi-value conversion, when the target pixel subjected to the binarization has a dot, a portion expressed as a dot present by the smoothing corrects the target pixel.
  • the previous density value a portion expressed as no dot by the smoothing is converted into a density value of a pixel adjacent to the portion, and if the binarized target pixel has no dot, the smoothing is performed by the smoothing. Without dots The portion indicated by a dot is converted into the density value of the target pixel before correction, and the portion indicated by the smoothing as having a dot is converted into the density value of an adjacent pixel.
  • the portion represented as a dot by the smoothing corrects the target pixel.
  • the previous density value, the portion represented as no dot by the smoothing was converted into an intermediate value between the density value of the pixel adjacent to the portion and the density value of the pixel of interest before correction, and the binarization was performed.
  • the portion expressed as no dot by the smoothing is the density value before correction of the target pixel
  • the portion expressed as having a dot by the smoothing is a pixel adjacent to the portion. It is characterized in that it is converted into an intermediate value between the density value and the density value of the target pixel before correction.
  • FIG. 1 is a block diagram showing a configuration example of a color image forming apparatus of the present invention.
  • FIG. 2 is a diagram showing a configuration example of a color laser printer using the color image forming apparatus of the present invention.
  • FIG. 3 is a flowchart showing an example of the binarization processing, the LUT collation processing, the multi-value processing, and the color tone comparison.
  • FIG. 4 is a block diagram showing a configuration example of a conventional laser printer.
  • FIG. 5 is a diagram showing an example of a smoothing process of binary image data.
  • FIG. 6 is a block diagram illustrating a configuration example of a conventional binary image forming apparatus that performs a smoothing process on binary image data.
  • FIG. 7 shows an example of a smoothing process for the extracted pattern arrangement signal.
  • FIG. 8 is a block diagram showing a configuration example of a multilevel laser printer.
  • FIG. 9 is a diagram showing an example of the smoothing processing of the quaternary image data.
  • FIG. 10 is a block diagram showing a configuration example of a conventional multilevel image forming apparatus for performing a smoothing process of multilevel image data.
  • FIG. 11 is a block diagram showing another configuration example of a conventional multi-level image forming apparatus for performing a smoothing process on multi-level image data.
  • FIG. 12 is a flowchart showing an example of the binarization processing, the LUT collation processing, and the multi-value processing.
  • FIG. 13 is a diagram showing from the extraction of the evaluation window to the straightening process.
  • FIG. 14 is a flowchart showing an example of the evaluation window binary process A and the evaluation window binary process B.
  • FIG. 15 is a diagram showing the result of the binarization process.
  • FIG. 16 is a diagram showing an embodiment in a case where a simple replacement process is used as the multi-value processing.
  • FIG. 17 is a diagram showing an embodiment in which averaging processing is used as multi-value processing.
  • FIG. 18 is a diagram showing a configuration of a color printer using the conventional multilevel image forming apparatus shown in FIG. BEST MODE FOR CARRYING OUT THE INVENTION
  • FIG. 1 is a block diagram showing a configuration example of a color image forming apparatus of the present invention.
  • the optical modulation signal generation circuit 81 shown in FIG. 1 includes an image memory reading section 43, a smoothing circuit 82, and a digital-to-analog conversion section 53.
  • FIG. 1 the same reference numerals as those in FIGS. 4 and 11 denote the same or corresponding objects as those shown in FIGS. 4 and 11, and a description thereof will be omitted.
  • FIG. 2 is a diagram showing a configuration example of a color laser printer using the color image forming apparatus of the present invention. As shown in FIG. 2, this color laser printer has four image memories 41a to 41d, four optical modulation signal generation circuits 81a to 81d, and four optical units 2a to 2 d, 4 image forming units 1 la ⁇ lid, and control circuit
  • Each optical modulation signal generation The paths 81a to 81d are the same as the configuration of the optical modulation signal generation circuit 81 shown in FIG.
  • the optical units 2a to 2d and the image forming units 11a to 11d have the same configuration as the optical unit 2 and the image forming unit 11 shown in FIG. That is, as shown in FIG. 1, the image memory 41, the optical modulation signal generation circuit 81, the optical unit 2, and the image forming unit 11 are connected to each color plane, C, M, Y, ⁇ components, Prepare for each. 2, the same reference numerals as those in FIGS. 4 and 18 denote the same or corresponding objects as those shown in FIGS. 4 and 18, and a description thereof will be omitted.
  • the image expanding means corresponds to the image expanding section 71
  • the image storing means corresponds to the image memory 41, the image memory reading section 43, and the line buffer 47.
  • the binarization processing unit corresponds to the binarization processing unit 63
  • the correction unit corresponds to the correction unit 83
  • the determination unit corresponds to the color tone comparison unit 84. I do.
  • FIG. 3 is a flowchart showing an example of the binarization processing, the LUT collation processing, the multi-value processing, and the color tone comparison.
  • the same reference numerals as those in FIG. 12 indicate the same processes as those of the object shown in FIG. 12, and a description thereof will be omitted.
  • the color tone comparison unit 84 calculates the color tone by performing color synthesis on the corrected C, M'Y'K 'values obtained from the optical modulation signal generation circuits 81a to 81d of each color, and The CMYK values before correction obtained from the image memories 41a to 41d of the respective colors are color-synthesized to calculate a color tone (S8), and the process proceeds to step S9.
  • step S9 the color difference between the color tone before correction and the color tone after correction is calculated, and it is determined whether the color difference is equal to or greater than a set value.
  • the set value is 1, for example. If the color difference is equal to or greater than the set value according to the result of the determination in step S9, it is determined that a false edge color has occurred, and the process proceeds to step S10.
  • a control signal is output to the correction unit 83 for each color so that the CMYK values before correction are discarded and output.
  • step S10 (1 1 is set to (1 13, (1 1 is set to (1 1 1), and this flowchart is ended.)
  • the color difference If the value is less than the set value, the color tone comparing section 84 sends the corrected C'M'Y'K 'value to the correcting section 83 for each color so as to output the value as it is. Outputs control signal.
  • the color tone comparison the lightness change is not easily recognized as a false edge color, and the color element change is likely to be a problem. Therefore, it is desirable to specify the color element change amount.
  • the CMYK space is converted to the Lab space, and the changes in the ab coordinates are compared.
  • the color tone before correction is expressed as Lab
  • the color tone after correction is expressed as L'a'b ', which is converted from CMY K space to Lab space, and each is projected on the ab plane. Is represented by ⁇ (a-a ') 2 + (b-b') 2 ⁇ 2 .
  • the present invention is applied to a laser printer, but it goes without saying that the present invention can be similarly applied to an LED printer, an ink jet printer, and a display.
  • a color image forming apparatus that forms a multi-valued color image can use a look-up table that is equivalent to a binary printer for a necessary look-up table. This makes it possible to prevent the jaggedness and the like generated during image formation from being noticeable, and to prevent the occurrence of a false color of the edge due to the smoothing process. That is, a low-cost multi-value color image forming smoothing process with a simple configuration can be realized.

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  • Signal Processing (AREA)
  • Facsimile Image Signal Circuits (AREA)
  • Image Processing (AREA)

Abstract

La présente invention concerne un dispositif de création d'image couleur permettant de lisser des données d'image couleur saisies. Les données d'image couleur sont divisées en ensembles de données d'image multiniveaux contenant des données d'image multiniveaux représentant la valeur de densité pour chaque couleur; le motif d'une zone prédéterminée incluant un pixel d'intérêt devant être retiré par lissage des pixels associés aux données d'image multiniveaux est extrait pour chaque couleur; lorsqu'une instruction externe active une correction par binairisation du motif, lissage du pixel d'intérêt et conversion du pixel d'intérêt en données multiniveaux, la valeur de densité après correction autour du pixel d'intérêt est délivrée en sortie; lorsqu'une instruction externe inactive une correction, la valeur de densité avant la correction autour du pixel d'intérêt est délivrée en sortie pour chaque couleur; on calcule ensuite la différence de couleur entre la teinte de couleur après la correction calculée à partir des valeurs de densité de toutes les composantes couleur après correction et la teinte de couleur avant la correction calculée à partir des valeurs de densité de toutes les composantes couleur avant correction; la correction est considérée comme valide si la différence de couleur appartient à une plage préétablie et elle est considérée comme invalide si la différence de couleur n'appartient pas à cette plage; et le résultat de cette évaluation est transformé en instruction.
PCT/JP2002/004651 2002-05-14 2002-05-14 Dispositif et procede de creation d'image couleur WO2003096675A1 (fr)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2009294382A (ja) * 2008-06-04 2009-12-17 Canon Inc 画像形成装置、その制御方法及び制御プログラム
CN113411466A (zh) * 2021-05-08 2021-09-17 华南理工大学 基于彩色印刷生产系统的多色彩色差智能校正方法及系统

Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH06284289A (ja) * 1992-10-28 1994-10-07 Canon Inc 画像処理方法及び装置
JPH10145588A (ja) * 1996-11-08 1998-05-29 Ricoh Co Ltd 画像データ処理装置
JPH10145587A (ja) * 1996-11-12 1998-05-29 Ricoh Co Ltd 画像データ処理装置
JPH11261830A (ja) * 1998-03-10 1999-09-24 Konica Corp 画像処理方法および画像処理装置
JPH11298738A (ja) * 1998-04-09 1999-10-29 Fuji Photo Film Co Ltd 画像処理方法および装置
JP2000092327A (ja) * 1998-09-08 2000-03-31 Ricoh Co Ltd 画像形成装置
JP2001298620A (ja) * 1999-08-19 2001-10-26 Ricoh Co Ltd 画像形成装置

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH06284289A (ja) * 1992-10-28 1994-10-07 Canon Inc 画像処理方法及び装置
JPH10145588A (ja) * 1996-11-08 1998-05-29 Ricoh Co Ltd 画像データ処理装置
JPH10145587A (ja) * 1996-11-12 1998-05-29 Ricoh Co Ltd 画像データ処理装置
JPH11261830A (ja) * 1998-03-10 1999-09-24 Konica Corp 画像処理方法および画像処理装置
JPH11298738A (ja) * 1998-04-09 1999-10-29 Fuji Photo Film Co Ltd 画像処理方法および装置
JP2000092327A (ja) * 1998-09-08 2000-03-31 Ricoh Co Ltd 画像形成装置
JP2001298620A (ja) * 1999-08-19 2001-10-26 Ricoh Co Ltd 画像形成装置

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2009294382A (ja) * 2008-06-04 2009-12-17 Canon Inc 画像形成装置、その制御方法及び制御プログラム
CN113411466A (zh) * 2021-05-08 2021-09-17 华南理工大学 基于彩色印刷生产系统的多色彩色差智能校正方法及系统
CN113411466B (zh) * 2021-05-08 2022-09-20 华南理工大学 基于彩色印刷生产系统的多色彩色差智能校正方法及系统

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