JP2006100997A - Image processing apparatus and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image processing apparatus and method for properly discriminating attributes over a wide-range region of image data. <P>SOLUTION: A pixel attribute discrimining section 102 discriminates the color attribute of a target pixel, on the basis of a second luminance signal obtained by multiplying coefficients with first luminance signals, the coefficients being individually set to the first luminance signals comprising pixels of a color multi-value image and received from an original read section. A main control section 103 counts arrangement attributes discriminated in accordance with the arrangement of color attributes as to 32 lines, in a block obtained by dividing a band of 64 lines in the color multi-value image into eight parts in the main scanning direction and counts the number of discriminated color attributes. A parameter, denoting the image feature of the concerned block, is calculated on the basis of the counted values, and the image attribute of the band is discriminated on the basis of the image attribute of the discriminated block, in response to the counts and the parameter obtained. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

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

  2. Description of the Related Art Conventionally, in an image forming apparatus using an ink jet system for a recording unit, a head that is longer than other color image forming heads is known as a black (Bk) image forming head. In this image forming apparatus, it is determined whether the original is a monochrome area or a color area in units of lines, and the line group determined to be a monochrome area is image-formed by this long black image forming head. Even in the case of a color image, the range in which an image can be formed at a time can be expanded without impairing the image quality, and the recording speed can be improved (see Patent Document 1).

JP 2003-237191 A

  However, since the luminance signal read by the reading unit has been subjected to image processing as it is, the line group that should originally be determined to be monochrome is determined to be color by the deviation in linearity that occurs in the reading unit, so Since an image is formed by the head, it takes a long time to form an image of a color document including black.

  Similarly, in the area that should originally be white, when the line group is determined to be color, the entire image is covered with color and the color changes.

  According to the first aspect of the present invention, there is provided an input unit that inputs a first luminance signal for each pixel of a color multi-valued image, and a linearity shift of the first luminance signal input by the input unit to correct the second luminance signal. Correction means for obtaining a luminance signal, color attribute determination means for determining a color attribute for each pixel based on the second luminance signal obtained by correction by the correction means, and color attribute determined by the color attribute determination means Are stored in a first line group consisting of a predetermined number of lines in the sub-scanning direction, and storage means for storing pixels in a predetermined area including the target pixel, and the first line The group is further divided into a plurality of blocks in the main scanning direction, a second line group consisting of a predetermined number of lines is extracted from the first line group belonging to each block, and the array of the color attributes in the storage means Determine the array attribute according to First counting means for counting the number of each array attribute; second counting means for counting the number of pixels having the color attribute determined by the color attribute determining means for the block; and the first and first Calculation means for calculating a parameter indicating an image feature of the first block based on the count value obtained by the counting by the two counting means, the count value by the first and second counting means, and the calculation A block attribute determining unit that determines an image attribute of the first block according to a parameter calculated by the unit, and an image attribute of the first line group based on a determination result by the block attribute determining unit. And a line attribute determining means for determining.

  In the first aspect of the present invention, the linearity correction means sets a coefficient for each luminance signal individually for the first luminance signal, and multiplies each luminance signal by the individually set coefficient. Thus, it is possible to have coefficient multiplying means for obtaining a second luminance signal having a predetermined luminance level value.

  In the first or second aspect of the invention, the first line group and the second line based on the determination result for the first line group by the line attribute determination means and the determination result for the predetermined second line group. The image forming apparatus may further include a final determination unit that determines an image attribute of a third line group that is included in common with the line group.

  4. The color attribute determination unit according to claim 1, wherein the color attribute determination unit determines whether the pixel is a white pixel, and determines whether the pixel is a black pixel. Black pixel determination means and color pixel determination means for determining whether or not the pixel is a color pixel can be provided.

  In the invention of claim 4, the white pixel determining means can determine whether or not the pixel is a white pixel by comparing the second luminance signal with a predetermined threshold value.

  According to a fourth aspect of the present invention, the black pixel determining means is based on a comparison result between the second luminance signal and the predetermined threshold value and a comparison value between the difference value between the color components of the second luminance signal and the predetermined threshold value. It can be determined whether or not the pixel is a black pixel.

  In the invention of claim 4, when the color pixel determining means determines that the pixel is not a white pixel by the white pixel determining means and the black pixel determining means determines that the pixel is not a black pixel, the color pixel determining means If it is determined that the pixel is a color pixel, and the corresponding pixel in the previous line in the sub-scanning direction of the line including the color pixel is determined to be a color pixel by the color attribute determination unit, the color attribute of the target pixel is If the corresponding pixel in the previous line in the sub-scanning direction of the line including the color pixel is not determined to be a color pixel by the color attribute determination unit, the color attribute of the target pixel is determined. It can be determined as a single color pixel.

  In a seventh aspect of the invention, the storage means includes a line holding means for holding a color attribute for each pixel for a predetermined line in the color multi-valued image, and a pixel holding unit for each pixel for the line held in the line holding means. Window storage means for storing the color attribute and the color attribute for each pixel for the next line in the sub-scanning direction of the line in a window format can be provided.

  The window storage means stores the color attribute for each pixel in a first window format in which the main scanning direction is M (M is a positive integer) pixels and the sub-scanning direction is 2 pixels. A first window storing means, and a second window for storing color attributes for each pixel in a second window format comprising N pixels (N is a positive integer) in the main scanning direction and two pixels in the sub-scanning direction. Storage means.

  In the invention of claim 9, the first counting means calculates the number of windows in the first window storage means when the target pixel is a color pixel and at least one black pixel is adjacent to the target pixel. In the first array attribute counting means for obtaining the first array attribute number by counting for each second block, and in the second window storage means, color pixels continue in the vertical direction in the window area excluding the four pixels at both ends. And second array attribute counting means for obtaining the second array attribute number by counting the number of windows for each of the second blocks when no black pixel exists in the window area including the four pixels at both ends. In the second window storage means, the number of windows when the continuous color pixel exists in a window region in which the main scanning direction is I pixels and the sub-scanning direction is 2 pixels is set to the second block memory. In the third array attribute counting means for obtaining the third array attribute number by counting each pixel and the first window storage means, the pixel of interest is a color pixel, and a black pixel is around the color pixel. Fourth arrangement attribute counting means for counting the number of windows when they do not exist for each of the second blocks to obtain a fourth arrangement attribute number can be provided.

  11. The fifth array attribute counting means according to claim 10, wherein the second counting means counts the pixels determined to be black pixels by the black pixel determining means for each of the second blocks to obtain a black pixel count value. Can be provided.

  In the invention of claim 10, the calculating means includes a first computing means for obtaining a first parameter using a ratio between the first array attribute number and the second array attribute number; a fourth array attribute number; And a second calculation means for obtaining a second parameter using a ratio with the black pixel count value.

  In the first aspect of the present invention, the block attribute determining means compares the count values of the first and second counting means and the first parameter and the second parameter calculated by the calculating means with a predetermined threshold value. By doing so, the image attribute of the first block can be determined.

  In the invention of claim 3, the line attribute determining means can determine whether or not the image attribute of the first line group is monochrome according to the result determined by the block attribute determining means. When the image attributes of the first line group and the second line group are both determined to be monochrome, the image attribute of the third line group included in common can be determined to be monochrome.

  In the invention of claim 3, the first line group and the second line group may have the same number of lines.

  In the invention of claim 15, the third line group may be half the number of lines of the first line group and the second line group.

  The invention according to claim 3 may further comprise image processing means for performing image processing on the third line group according to the image attribute of the third line group determined by the final determining means.

  The invention according to claim 4 may further comprise image recording means for recording the color multi-valued image in a predetermined line unit, and the predetermined line unit has the same number of lines as in the third line group. Can do.

  In the invention of claim 18, the image recording means can include an ink-jet monochrome head and a color head, and the monochrome head can be longer than the color head.

  The invention according to claim 20 is a correction step for correcting a linearity shift of the first luminance signal for each pixel of the color multi-valued image to obtain a second luminance signal, and a second obtained by correction by the correction step. A color attribute determination step for determining a color attribute for each pixel based on the luminance signal of the pixel, and the color attribute determined by the color attribute determination step for a pixel in a predetermined area including the target pixel in a predetermined storage device A storage step for storing, and the color multi-valued image is divided into a first line group composed of a predetermined number of lines in the sub-scanning direction, and the first line group is further divided into a plurality of blocks in the main scanning direction; Dividing, extracting a second line group consisting of a predetermined number of lines from the first line group belonging to each block, determining an array attribute according to the array of the color attributes in the storage means, and determining the number of each array attribute The A first counting step for counting, a second counting step for counting the number of pixels having the color attribute determined by the color attribute determining step for the block, and a coefficient by the first and second counting steps. On the basis of the counted value, a calculation step for calculating a parameter indicating the image feature of the first block, a count value obtained by coefficient calculation by the first and second counting steps, and a calculation by the calculation step A block attribute determination step for determining an image attribute of the first block according to the determined parameter, and a line for determining an image attribute of the first line group based on a determination result by the block attribute determination step And an attribute determination step.

  In the invention of claim 20, the linearity correction step sets a coefficient for each luminance signal individually for the first luminance signal, and multiplies each luminance signal for the coefficient set individually. Thus, a coefficient multiplying step for obtaining a second luminance signal having a predetermined luminance level value can be provided.

  The invention according to claim 20 or 21 is characterized in that the first line group and the first line group are determined based on the determination result for the first line group in the line attribute determination step and the determination result for the predetermined second line group. The image forming apparatus may further include a final determination step of determining an image attribute of a third line group included in common with the two line groups.

  23. The invention according to claim 20, wherein the color attribute determining step includes a white pixel determining step for determining whether or not the pixel is a white pixel, and a black pixel determining step for determining whether or not the pixel is a black pixel. And a color pixel determination step for determining whether or not the pixel is a color pixel.

  In the invention of claim 22 or 23, the color pixel determining step can determine that the pixel is a color pixel when it is determined NO in both the white pixel determining step and the black pixel determining step. If the corresponding pixel in the previous line in the sub-scanning direction of the line including the color pixel is determined to be a color pixel by the color attribute determination step, the color attribute of the target pixel is determined to be a continuous color pixel, When the corresponding pixel in the previous line in the sub-scanning direction of the line including the color pixel is not determined to be a color pixel by the color attribute determination step, the color attribute of the target pixel is determined as a single color pixel Can do.

  According to a twenty-fifth aspect of the present invention, there is provided a computer program for causing a computer to separately calculate a coefficient for each luminance signal based on a first luminance signal for each pixel of a color multilevel image. A coefficient multiplication procedure for obtaining a second luminance signal having a predetermined luminance level value by multiplying each luminance signal by an individually set coefficient, and based on the second luminance signal, A color attribute determination procedure for determining a color attribute of a pixel; a storage procedure for storing the color attribute determined by the color attribute determination procedure in a predetermined storage device for pixels in a predetermined area including the target pixel; The arrangement of the color attributes in the storage device for the second block having a predetermined number of lines in the first block obtained by dividing the predetermined first line group in the color multi-valued image in the main scanning direction. Therefore, a first counting procedure for counting the array attributes to be determined, a second counting procedure for counting the color attributes determined by the color attribute determining procedure for the second block, the first and first On the basis of the count value obtained by the second counting procedure, the calculation procedure for calculating the parameter indicating the image feature of the first block, the count value by the first and second counting means, and the calculation procedure are used. A block attribute determination procedure for determining an image attribute of the first block according to the determined parameter, and a line attribute determination for determining an image attribute of the first line group based on a determination result by the block attribute determination procedure Based on the determination result for the first line group and the determination result for the predetermined second line group according to the procedure and the line attribute determination procedure, To execute a determining final determination steps image attributes of the third group of lines included in common with the in-group second line group.

  A computer-readable recording medium according to a twenty-sixth aspect of the invention records the computer program according to the twenty-fifth aspect.

  According to the present invention, it is possible to determine appropriate attributes of a wide range of image data with a simple configuration, and to form a high-quality image.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows an embodiment of the present invention. This is an example of an image processing apparatus. As shown in FIG. 1, in this image processing apparatus, a document reading unit 101, a pixel attribute determination unit 102, a main control unit (CPU) 103, and an image processing unit 105 are connected to each other via a bus. ing.

  The document reading unit 101 uses a CCD or CIS (contact image sensor) to color image data of a document, that is, red (hereinafter referred to as “R”), green (hereinafter referred to as “G”), blue (hereinafter referred to as “B”). Multi-valued image data is read to obtain a luminance signal for each pixel. In a CCD or CIS for consumer use, linearity deviation may occur for each luminance component as shown in FIG. 7, and when the linearity deviation occurs, RGB luminance components are not output with the same value even when a gray image is read. In a pixel attribute determination unit 102, which will be described later, an original gray image is determined as a color image.

  In order to reduce the deviation of the linearity, the RGB luminance signal data read by the document reading unit 101 is sent to the coefficient calculation unit 106. The coefficient calculation unit 106 multiplies a preset coefficient so as to obtain a predetermined luminance signal level for each luminance component, and sends the obtained luminance signal to the pixel attribute determination unit 102.

  Specifically, when reading the background of a document at the time of pre-scanning, the input luminance data is 256 gradations, and the CCD can obtain luminance values of R = 228, G = 241, and B = 252 for RGB, respectively. Or CIS, the coefficient values to be multiplied are set as Kr = 1.12, Kg = 1.06, Kb = 1.01, and when the obtained luminance value is multiplied by the coefficient value, R = The values 255, G = 254, B = 255 are obtained.

  By applying such processing to the luminance signal, the luminance data of R, G, B is flattened and the balance of the white level is adjusted, so that the area that is originally white can be increased.

  Next, the pixel attribute determination unit 102 determines the attribute for each pixel by comparing the color image data read by the document reading unit 101 with a predetermined threshold, and counts for each attribute.

  The main control unit 103 controls the entire image processing apparatus via the system bus, and performs attribute determination using the attribute-specific count value counted by the pixel attribute determination unit 102. The main control unit 103 is connected to the storage unit 104. The storage unit 104 is used when the main control unit 103 makes a determination for a predetermined line. The image processing unit 105 receives the determination result determined by the main control unit 103 and performs high image quality processing.

  FIG. 2 is a block diagram illustrating a detailed configuration of the pixel attribute determination unit 102 of FIG. In FIG. 2, registers 201 to 209 are D flip-flops that store parameters and the like necessary for determining, for each pixel, the attribute of color image data read by the document reading unit 101 in the pixel attribute determination unit 102. DFF) and the like, and a predetermined threshold is set by the main control unit 103.

  WTHR, WTHG, and WTHL are threshold setting registers for determining whether each pixel data input by the document reading unit 101 is a white pixel. In WTHR, a determination level relating to white pixel determination of the R signal level of the pixel data input by the document reading unit 101 is stored. Similarly, a determination level related to white pixel determination at the G signal level is stored in WTHG, and a determination level related to white pixel determination at the B signal level is stored in WTHG.

  Further, BTHR, BTHG, BTHB, DRG, DGB, and DRB are threshold setting registers for determining whether each pixel data input by the document reading unit 101 is a black pixel. In BTHR, a determination level relating to black pixel determination of the R signal level of the pixel data input by the document reading unit 101 is stored. Similarly, a determination level related to black pixel determination of the G signal level is stored in BTHG, and a determination level related to black pixel determination of the B signal level is stored in BTHB.

  On the other hand, the DRG is a threshold setting register for determining whether or not the pixel data input by the document reading unit 101 is a black pixel, and a threshold relating to the absolute value of the difference between the R signal level and the G signal level. Is set. Similarly, a threshold relating to the absolute value of the difference between the G signal level and the B signal level is set in DGB, and a threshold relating to the absolute value of the difference between the R signal level and the B signal level is set in DRB.

  The color image data read by the document reading unit 101 is compared with the threshold value stored in the threshold value setting register for each signal component of each pixel. That is, regarding the white pixel determination, the comparator 213 compares the R signal level of the input pixel data with the threshold set by WTHR. Then, when the R signal level of the input pixel is larger than a predetermined threshold set by WTHR, the comparator 213 outputs a signal that satisfies the condition (“Hi level”).

  Similarly, the G signal level of the input pixel data is compared with the threshold value set by WTHG by the comparator 214, and the B signal level of the input pixel data is compared with the threshold value set by WTB by the comparator 215. . When each is larger than a predetermined threshold set by WTHG and WTHG, the comparator 214 and the comparator 215 output a signal (“Hi level”) that satisfies the condition. Thereby, it can be determined whether or not the input pixel data is a white pixel.

  On the other hand, regarding the black pixel determination, first, the comparator 216 compares the R signal level of the input pixel data with the threshold set by BTHR. The comparator 216 outputs a signal (“Hi level”) that satisfies the condition when the R signal level of the input pixel is smaller than a predetermined threshold set by BTHR. Similarly, the G signal level of the input pixel data is compared with the threshold value set by BTHG by the comparator 217, and the B signal level of the input pixel data is compared with the threshold value set by BTHB by the comparator 218. When each is smaller than the threshold value set by BTHG and BTHB, the comparator 217 and the comparator 218 output a signal (“Hi level”) that satisfies the condition.

  Further, regarding the black pixel determination, the comparator 219, the comparator 220, and the comparator 221 perform determination using absolute values of differences between the R signal level, the G signal level, and the B signal level of the input pixel data. That is, the subtracter 210 calculates the absolute value of the difference between the R signal level and the G signal level of the input pixel data. And it compares with the threshold value regarding the absolute value of the difference of R signal level regarding the black pixel determination set by DRG, and G signal level. Comparator 219 outputs a signal (“Hi level”) that satisfies the condition when the calculation result by subtractor 210 is smaller than the threshold set by DRG.

  Similarly, the comparator 220 calculates the absolute value of the difference between the G signal level and the B signal level of the input pixel data by the subtractor 211, and the G signal level and the B signal level related to the black pixel determination set by the DGB. A comparison is made with a threshold relating to the absolute value of the difference of When the calculation result by the subtractor 211 is smaller than the threshold set by DGB, a signal that satisfies the condition (“Hi level”) is output. Further, the comparator 221 calculates the absolute value of the difference between the R signal level and the B signal level of the input pixel data by the subtractor 212 and the difference between the R signal level and the B signal level related to the black pixel determination set in the DRB. Compare with the threshold value for the absolute value of. When the calculation result by the subtractor 212 is smaller than the threshold set by DRB, a signal that satisfies the condition (“Hi level”) is output. As described above, by satisfying the condition when the absolute value of the difference between the color components is smaller than the predetermined threshold, it is possible to determine an achromatic color such as gray as a black pixel.

Next, the white, black, and color pixel determination of the input pixel data will be described.
The white pixel determination unit 222 performs white pixel determination of input pixels based on output signals from the comparators 213 to 215. Specifically, when all the outputs of the connected comparators 213 to 215 are signals that satisfy the condition (“Hi level” signal), the input pixel is determined to be a white pixel and a determination signal is output. .

  The black pixel determination unit 223 performs black pixel determination of input pixels based on output signals from the comparators 216 to 221. Specifically, when all the outputs of the connected comparators 216 to 221 are signals that satisfy the condition (“Hi level” signal), the input pixel is determined to be a black pixel and a determination signal is output. . The black pixel counting unit 231 receives the output signal from the black pixel determining unit 223 and counts the number of black pixels.

  The determination of the color pixel of the input pixel data is performed with reference to the output signal of the white pixel determination unit 222 and the output signal of the black pixel determination unit 223. That is, when the outputs from the white pixel determination unit 222 and the black pixel determination unit 223 are not signals satisfying both conditions (“Hi level”), the input pixel data is determined as a color pixel and a determination signal is output. As described above, the input pixel data can be determined as one of white, black, and color pixels.

  That is, the pixel attribute determination unit 102 in the image processing apparatus according to the present embodiment determines whether or not the target pixel is a white pixel, and whether or not the pixel is a black pixel. A black pixel determination unit 223 for determining and a color pixel determination unit 224 for determining whether or not the pixel is a color pixel are provided.

  In the image processing apparatus according to the present embodiment, the white pixel determination unit 222 determines whether or not the target pixel is a white pixel by comparing the input luminance signal with a predetermined threshold. Features. Further, the black pixel determination unit 223 determines that the target pixel is a black pixel based on the comparison result between the input luminance signal and the predetermined threshold value and the comparison value between the difference value between the color components of the luminance signal and the predetermined threshold value. It is characterized by determining whether or not there is.

  Next, a pixel attribute classification method for the target pixel will be described. The determination results by the white pixel determination unit 222, the black pixel determination unit 223, and the color pixel determination unit 224 are input to the small window processing unit 225 and the large window processing unit 226. Further, a memory 232 is connected to the small window processing unit 225 and the large window processing unit 226. The memory 232 has a storage capacity of 2 bits per input pixel and the number of pixels in the main scanning direction.

  FIG. 3 is a diagram showing a window configuration for processing in the small window processing unit 225. FIG. 4 is a diagram showing a processing window configuration in the large window processing unit 226. As shown in FIGS. 3 and 4, in this embodiment, the small window processing unit 225 performs processing by applying a window size of 3 pixels in the main scanning direction and 2 pixels in the sub-scanning direction. The large window processing unit 226 applies a window size of 32 pixels in the main scanning direction and 2 pixels in the sub-scanning direction.

  In FIG. 3, reference numerals 301 to 306 denote registers for holding the determination results corresponding to the input pixels, respectively, and the shift register in which the stored data is shifted to the subsequent register for each line at the timing when the pixel data is input. Composed. That is, the storage data of the register 301 is stored in the register 302 and the storage data of the register 304 is stored in the register 305 at the timing when the pixel data is input.

  Also in FIG. 4, as in FIG. 3, reference numerals 401 to 464 denote registers that hold the determination results corresponding to the input pixels, and the data stored in the subsequent register for each line at the timing when the pixel data is input. Is constituted by a shift register that shifts. In other words, the storage data of the register 401 is stored in the register 402 and the storage data of the register 433 is stored in the register 434 at the timing when the pixel data is input.

  The register 301 and the register 401 store the determination result of the pixel on the previous line obtained from the memory 232, and the register 304 and the register 433 store the determination result of the input pixel.

  That is, in the image processing apparatus according to the present embodiment, the color attribute for each pixel is retained for a predetermined line in the color multi-valued image, the color attribute for each pixel for the retained line, and the sub-line of the line. The color attribute for each pixel for the next line in the scanning direction is stored in a window format.

  In the image processing apparatus according to the present embodiment, the color attribute for each pixel is stored in the memory 232 in the first window format configured by M pixels in the main scanning direction and 2 pixels in the sub scanning direction. The color attribute for each pixel is stored in a second window format constituted by N pixels in the main scanning direction and two pixels in the sub-scanning direction. In the present embodiment, M is 3 and N is 32.

  The pixel attribute determination of the target pixel in the small window processing unit 225 and the large window processing unit 226 is based on the determination result of each pixel on the previous line and the pixel determination result on the current reading line, as shown in FIGS. Done.

  Since the determination result data read from the memory 232 is unnecessary after being stored in the register 301 and the register 401, the determination result of the input pixel is included in the address of the memory 232 where the determination result data is stored. Is newly remembered. Therefore, the memory 232 that holds the determination result of the previous line only needs to have a minimum capacity for the number of pixels in the main scanning direction for one line of the input document image data.

  The data stored in the registers 301 to 306, the registers 401 to 464, and the memory 232 are initialized to white pixel determination results in units of processing originals or processing lines. Further, the register 305 shown in black in FIG. 3 corresponds to the determination data of the target pixel to be determined.

  The data stored in each register shown in FIGS. 3 and 4 is the small window processing unit 225 and the large window processing unit 226 when the pixels input to the small window processing unit 225 and the large window processing unit 226 are white pixels. Stores 2-bit data indicating that the input pixel is a white pixel in the register. Here, in the present embodiment, data indicating that the input pixel is a white pixel is “11”.

  When the input pixel is a black pixel, the small window processing unit 225 and the large window processing unit 226 store 2-bit data indicating that the input pixel is a black pixel in a register. In this embodiment, data indicating that the input pixel is a black pixel is “00”.

  Further, when the input pixel is a color pixel, the small window processing unit 225 and the large window processing unit 226 store 2-bit data indicating that the input pixel is a color pixel in a register. In this embodiment, data indicating that the input pixel is a color pixel is “10” or “01”. That is, “01” indicating continuous color pixel determination when the pixel determination result of the previous line of the input pixel is a color pixel, and single color pixel determination when the pixel determination result of the previous line of the input pixel is a white pixel or a black pixel “10” indicating “” is stored in the register. Thus, in this embodiment, not only whether or not the input image data is a color pixel but also whether the color pixel is a continuous color pixel or a single color pixel is determined. Is possible.

  In other words, in the image processing apparatus according to the present embodiment, when the color pixel determination unit 224 determines NO in both the white pixel determination unit 222 and the black pixel determination unit 223, the target pixel is a color pixel. If the corresponding pixel in the previous line in the sub-scanning direction of the line including the color pixel is determined to be a color pixel, the color attribute of the target pixel is determined to be a continuous color pixel, and the color pixel is included. If the corresponding pixel in the previous line in the sub-scanning direction of the line is not determined to be a color pixel, the color attribute of the pixel of interest is determined to be a single color pixel.

  Next, processing in the edge color counting unit 228 will be described. The edge color counting unit 228 detects and counts color pixels associated with black characters by the small window processing unit 225. Specifically, at the timing when pixel data is input to the small window processing unit 225, the register 305 for the target pixel stores either “10” or “01” indicating the color pixel determination result. . When “00” indicating black pixel determination is stored around the pixel of interest, that is, in any of the registers 301 to 304 and the register 306, the small window processing unit 225 outputs a signal to the edge color counting unit 228. To do. The edge color counting unit 228 receives the output signal and counts the number of edge colors.

  Next, processing in the isolated color counting unit 227 will be described. The isolated color counting unit 227 detects and counts color pixels not associated with black characters by the small window processing unit 225. Specifically, at the timing when the pixel data is input to the small window processing unit 225, “10” or “01” indicating the color pixel determination result is stored in the register 305 for the target pixel. When “00” indicating black pixel determination is not stored around the pixel of interest, that is, in any of the registers 301 to 304 and the register 306, the small window processing unit 225 outputs a signal to the isolated color counting unit 227. To do. The isolated color counter 227 receives the output signal and counts the number of color pixels.

  Next, processing in the V color counting unit 230 will be described. The V color counting unit 230 detects and counts the color vertical ruled lines by the large window processing unit 226. Specifically, at the timing when the pixel data is input to the large window processing unit 226, “10” or “01” indicating the color pixel determination result in the registers other than the registers (registers 401, 432, 433, and 464) at both ends. ”Is stored vertically (for example, registers 416 and 448), and among all the registers including the registers at both ends, there is a register storing“ 00 ”indicating the black pixel determination result. If there is none, the large window processing unit 226 outputs a signal to the V color counting unit 230. The V color counting unit 230 receives the output signal and counts the number of V colors.

  Further, the block color counting unit 229 detects and counts color pixels over a wide area by the large window processing unit 226. Specifically, at the same timing as the V color counting unit 230, when “01” indicating the continuous color pixel determination result is stored in an area of 16 × 2 pixels or more in all the registers (for example, the registers 410 to 410). 425 and the registers 442 to 457 (when “01” is stored), the large window processing unit 226 outputs a signal to the block color counting unit 229. The block color counting unit 229 receives the output signal and counts the number of block colors. In the present embodiment, the area is 16 × 2 pixels as an example, but the present invention can be similarly applied to areas of other sizes.

  That is, when the pixel of interest is a color pixel in the small window processing unit 225 and at least one black pixel is adjacent to the pixel of interest in the pixel attribute determination unit 102 in the image processing apparatus according to the present embodiment. In the edge color counting unit 228 that obtains the first array attribute number by counting the number of windows for each second block, and the large window processing unit 226, color pixels continue in the vertical direction in the window area excluding the four pixels at both ends. And a V color counting unit 230 that counts the number of windows when there are no black pixels in the window area including the four pixels at both ends for each second block, and obtains a second array attribute number, and a large window In the processing unit 226, the number of windows when the continuous color pixel is present in the window region in which the main scanning direction is I pixels and the sub-scanning direction is 2 pixels is the second number. In the block color counting unit 229 that counts for each block to obtain the third array attribute number and the small window processing unit 225, when the pixel of interest is a color pixel and there is no black pixel around the color pixel An isolated color counting unit 227 that counts the number of windows for each second block to obtain a fourth array attribute number is provided.

  The main control unit 103 determines whether the predetermined area is a monochrome image or a color image using the counting results counted by the above-described respective counting units in the pixel attribute determination unit 102. Here, in this embodiment, the area for 64 lines in the sub-scanning direction is set to “1 band”, the main scanning direction is divided into 8 and the divided area is set to “1 block”, and determination is performed for each block. And The application of the present invention is not limited to the determination band unit of 64 lines in the sub-scanning direction, and can be similarly applied to an area wider or narrower than 64 lines. Further, the number of divisions in the main scanning direction is not limited to eight divisions, and the determination may be performed based on a division number larger or smaller than eight divisions.

  FIG. 5 is a flowchart for explaining a determination processing procedure for each band in the main control unit 103. First, at the timing when 1/2 of all 64 lines constituting the band, that is, 32 lines, is counted in each counting unit in the pixel attribute determination unit 102, the main control unit 103 sets the count value for each block. Read and reset the value of each counter (step S101). That is, in this embodiment, each counting unit is initialized at the timing when 32 lines are counted. Here, the storage unit 104 stores count values for 32 lines preceding the currently counted 32 lines. In addition, the reading timing of each count value in the present embodiment is not limited to each half of the number of lines in the band configuration, and may be more or less than that.

  Next, by adding the count value for the previous 32 lines stored in the storage unit 104 for each block and the count value for the current 32 lines read from each count unit, 64 lines of black, white The color pixel count value is calculated (step S102). After this addition operation is completed, the storage unit 104 stores the count values for the current 32 lines for each block.

Next, based on the V color count value and the edge color count value,
(V color ratio) = (number of V colors) / (number of edge colors) (1)
The V color rate is obtained by performing the above calculation (step S103). A block having a V color ratio close to 1 is considered to be a character area.

In step S104, based on the count value of the isolated color and the count value of the black pixel,
(Color rate) = (Number of isolated colors) / (Number of black pixels) (2)
The color ratio is obtained by performing the above calculation (step S104). It is considered that a wide area color image exists in the band having a large color rate.

  In other words, the present embodiment is characterized in that the main control unit 103 obtains a black pixel count value by counting the pixels determined to be black pixels by the black pixel determination unit 223 for each second block. In the image processing apparatus according to the present embodiment, the main control unit 103 obtains the first parameter using the ratio between the number of edge colors and the number of V colors, and sets the ratio between the number of isolated colors and the number of black pixels. To obtain the second parameter.

  As described above, the main control unit 103 obtains a determination element for 64 lines by performing the calculations of Expression (1) and Expression (2) based on the count value for each block of each counting unit for every 32 lines. And using the said determination element, the attribute determination of each block is performed as follows.

  First, it is determined whether or not the number of color blocks is larger than a predetermined value CBHTH (step S105). As a result, if the number of color blocks is larger than CBHTH, it is determined that the corresponding block is a color image area (step S110). This is because it is considered that there is a solid color image over a wide area in the block.

  On the other hand, if it is determined that the number of color blocks is not greater than CBHTH, it is determined whether or not the number of isolated colors is greater than a predetermined value KOTH (step S106). When it is determined that the number of isolated colors is greater than the predetermined value KOTH, it is determined that the area is a color image (step S110). This is because the block is considered to be a halftone dot image with few black dots, and the block is determined to be a color image region.

  On the other hand, if it is determined in step S106 that the number of isolated colors is not greater than the predetermined value KOTH, it is determined whether or not the number of color blocks is greater than CBLTH. When it is determined that the number of color blocks is larger than CBLTH (step S107), it is determined that the V color rate is smaller than the predetermined value VRTH (step S108), and the color rate is larger than the predetermined value CRTH. If it is determined (step S109), it is considered that a halftone image has been detected, so that the corresponding block is determined to be a color image region (step S110).

  In the present embodiment, CBLTH <CBHTH is set, but the present invention is not limited to this.

  On the other hand, in step S107, it is determined that the number of color blocks is not greater than CBLTH, in step S108, it is determined that the V color rate is not smaller than the predetermined value VRTH, or in S109, the color rate is predetermined. When it is determined that the value is not greater than the value CRTH and the number of V colors is determined to be greater than VTH (step S112), it is determined that the corresponding block is a color image region (step S110). ).

  If it is determined in step S112 that the number of V colors is not greater than VTH, it is determined that the corresponding block is a monochrome image region (S113). In other words, if a color ruled line is not detected for a block whose attribute has not been determined in the previous steps, it is determined that the block is a monochrome image region. That is, in the present embodiment, the main control unit 103 compares the counted value and the calculated first parameter (V color ratio) and second parameter (color ratio) with a predetermined threshold value. Thus, the image attribute of the block is determined.

  As described above, color or monochrome attribute determination is performed for each block, and color or monochrome attribute determination is performed for each band (64 lines) using the result.

  Next, an attribute determination method in band units using attribute determination results in block units will be described. If it is determined in step S110 that the corresponding block is a color image region, the current band is determined to be in color even if an undetermined block exists in the current band (step S111). That is, if there is at least one block determined to be color in the current band, the current band is determined to be color.

  In this embodiment, if there is at least one block determined to be color, the current band is determined to be color, but the application of the present invention is not limited to this. That is, color or monochrome attribute determination may be performed for all blocks in the current band, and color or monochrome attribute determination for the current band may be performed using a combination of attribute determination results for each block. For example, when there are three or more blocks determined to be in color, the current band may be determined to be a color image region. Further, when two blocks determined to be color are consecutive, the current band may be determined to be color.

  On the other hand, if it is determined in step S113 that the corresponding block is a monochrome image, and it is determined in step S114 that there is a block whose color or monochrome attribute has not been determined in the current band, the process proceeds to step S105. The same attribute determination is performed for the undetermined block.

  If it is determined in step S114 that the color or monochrome attribute determination has been completed for all the blocks in the current band, the current band is determined to be monochrome if all the blocks are determined to be monochrome ( Step S115).

  As described above, in this embodiment, color or monochrome attribute determination is performed in units of bands (64 lines). That is, in the present embodiment, the main control unit 103 determines whether the image attribute of the first line group is monochrome according to the determination result for the block, and uses the first line as a final determination unit. When the image attributes of the group and the second line group are both determined to be monochrome, the image attribute of the third line group included in common is determined to be monochrome.

  Furthermore, a final determination process using the determination result for each band may be performed. Therefore, the final determination process will be described below. FIG. 6 is a diagram for explaining an example of final attribute determination processing in units of 1/2 band (32 lines) in the present embodiment.

  In the present embodiment, as described above, based on the count value of each counting unit read by the main control unit 103 every 32 lines and the calculation results generated by the equations (1) and (2). The determination elements for one band (for 64 lines) are calculated, and the calculated determination elements are used for the determination processing for each block shown in FIG. 5, whereby color or monochrome attribute determination is performed for each band. .

  FIG. 6A shows an example in which a band of 64 lines is configured using data areas B1 to B4 each having 32 lines in a document image. In FIG. 6A, for 64-line data (band A) configured by the areas B1 and B2, color determination is performed for each area by the determination process shown in FIG. Similarly, a case where monochrome determination is performed for 64-line data (band B) by the regions B2 and B3 and monochrome determination is performed for 64-line data (band C) by the regions B3 and B4 is also shown.

  Hereinafter, an example in which the final determination is performed on the data illustrated in FIG. In the present embodiment, the final determination is not performed only by the determination for every 64 lines described above, but the region determination for 32 lines in which the determination results overlap is performed using the determination results of two bands configured by 64 lines. . That is, based on the determination result of the band A and the determination result of the band B, the final determination is performed on B2 that is the 32 line area. Similarly, based on the determination result of the band B and the determination result of the band C, the final determination for the 32-line region B3 is made. Specifically, the final determination result is set to monochrome only when the determination of the front and rear 64 lines including the data for 32 lines for final determination is monochrome determination.

  FIG. 6B shows the final determination result for the example of FIG. In this example, since the determination result of the band A is color and the determination result of the band B is monochrome, the region B2 is finally determined as color. In addition, regarding the region B3, since the determination result is monochrome for both the band B and the band C, the region B3 is finally determined as monochrome. In other words, the present embodiment is characterized in that the first line group and the second line group have the same number of lines. In addition, the present embodiment is characterized in that the third line group has half the number of lines as the first line group and the second line group.

  Since the determination result signal output from the main control unit 103 may be a signal indicating whether it is a monochrome image or a color image, 1-bit data is output. Specifically, “Hi level” is output when the image is a monochrome image, and “Low level” is output when the image is a color image. The determination result signal output from the main control unit 103 is used by the image processing unit 105 for high image quality processing. For example, a pixel determined to be a black pixel is determined as a black character region, and image processing suitable for the character region is performed. On the other hand, for a pixel determined not to be a black pixel, for example, image processing suitable for a photographic area is performed. That is, the present embodiment further includes an image processing unit 105 that performs image processing on the third line group according to the image attribute of the third line group determined by the main control unit 103. Features.

  In the present embodiment, the example in which the attribute determination for each band is performed as a software operation in the main control unit 103 has been described. However, the band determination may be implemented by hardware.

  In addition, each threshold value used for attribute determination in the present embodiment may be fixed, but may be arbitrarily changed according to the processing operation mode of the apparatus, for example.

  As described above, according to this embodiment, the linearity of CCD and CIS can be corrected with a simple configuration, and the determination accuracy of the pixel attribute determination unit can be improved. By improving the determination accuracy, it is determined that the line group that has been determined as a color image is a monochrome image, so printing can be performed with a monochrome head that is longer than the color head, thus improving the printing speed. be able to.

  Further, at the time of pre-scanning, the background of the original is captured in advance, the white data of the captured luminance data R, G, B is balanced (white balance), and the luminance data with white balance is determined to be white. Thus, it is possible to prevent color cast for an area that should be white. As a result, the white level can be reliably determined, so that the white area can be increased. Therefore, since the print area data printed at the time of printing becomes white, white can be skipped at the time of printing, and the number of scans of the recording head can be reduced, so that the printing speed can be greatly improved.

  In addition, since the area determined to be a monochrome image is not handled as color data and the amount of white data increases, the amount of data sent to the subsequent image processing unit or the like can be reduced, and the recording speed can be improved. Can do.

  As described above, the image processing apparatus according to the present invention includes a document reading unit 101 that inputs a first luminance signal for each pixel of a color multi-valued image, and a coefficient for each luminance of the first luminance signal. Coefficient multiplying means 106 which obtains a second luminance signal having a predetermined luminance level value by individually setting the signal and multiplying each luminance signal by a coefficient set individually; A pixel attribute determination unit 102 that determines the color attribute of the target pixel based on the luminance signal of the target pixel, and stores the determined color attribute for pixels within a predetermined area including the target pixel. A determination is made according to the stored color attribute arrangement for 32 lines in the first block obtained by dividing a band (first line group) of predetermined 64 lines in the value image into eight in the main scanning direction. Array genus And the determined color attribute is counted for 32 lines. Based on the counted value, a parameter indicating the image feature is calculated for the block, and the counted value and the calculated value are calculated. The image attribute of the block is determined according to the parameter, and the image attribute of the band is determined based on the determination result.

  In addition, the main control unit 103 of the image processing apparatus according to the present embodiment uses the determination result for the first line group and the determination result for the predetermined ½ band (second line group). The image attribute of the third line group included in common to the one line group and the second line group is determined.

  Note that the present embodiment can be applied to a system composed of a plurality of devices (for example, a host computer, an interface device, a reader, a printer, etc.), but an apparatus composed of a single device (for example, a copier, a facsimile) It may be applied to a device etc.

  Another object of the present invention is to supply a storage medium (or recording medium) in which a program code of software that implements the functions of the above-described embodiments is recorded to a system or apparatus, and the computer (or CPU or CPU) of the system or apparatus. Needless to say, this can also be achieved by the MPU) reading and executing the program code stored in the storage medium. In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the storage medium storing the program code constitutes the present invention. Further, by executing the program code read by the computer, not only the functions of the above-described embodiments are realized, but also an operating system (OS) or the like running on the computer based on an instruction of the program code. It goes without saying that a case where the function of the above-described embodiment is realized by performing part or all of the actual processing and the processing is included.

  Furthermore, after the program code read from the storage medium is written to a memory provided in a function expansion card inserted into the computer or a function expansion unit connected to the computer, the function is determined based on the instruction of the program code. It goes without saying that the CPU or the like provided in the expansion card or function expansion unit performs part or all of the actual processing, and the functions of the above-described embodiments are realized by the processing.

1 is a block diagram illustrating a configuration of an image processing apparatus according to an embodiment of the present invention. FIG. 2 is a block diagram illustrating a detailed configuration of a pixel attribute determination unit 102 in FIG. 1. It is a figure which shows the window structure for the process in the small window process part 225. It is a figure which shows the window structure for a process in the large window process part. 4 is a flowchart for explaining a determination processing procedure for each band in a main control unit 103; It is a figure for demonstrating an example of the final attribute determination process of a 1/2 band unit in the embodiment. It is a figure which shows the gap | deviation of a linearity.

Explanation of symbols

101 Document Reading Unit 102 Pixel Attribute Determination Unit 103 Main Control Unit 104 Storage Unit 105 Image Processing Unit 106 Coefficient Multiplying Unit

Claims (26)

Input means for inputting a first luminance signal for each pixel of the color multivalued image;
Correction means for correcting a linearity shift of the first luminance signal input by the input means to obtain a second luminance signal;
Color attribute determination means for determining a color attribute for each pixel based on the second luminance signal obtained by the correction by the correction means;
Storage means for storing the color attributes determined by the color attribute determination means for pixels in a predetermined area including the target pixel;
The color multi-value image is divided into a first line group composed of a predetermined number of lines in the sub-scanning direction, and the first line group is further divided into a plurality of blocks in the main scanning direction. A second line group consisting of a predetermined number of lines is extracted from the first line group to which it belongs, the array attribute is determined according to the array of color attributes in the storage means, and the number of each array attribute is counted Counting means;
Second counting means for counting the number of pixels having the color attribute determined by the color attribute determining means for the block;
Calculation means for calculating a parameter indicating an image feature of the first block based on the count values obtained by the first and second counting means;
A block attribute determining unit that determines an image attribute of the first block according to the count value obtained by the first and second counting units and the parameter calculated by the calculating unit;
An image processing apparatus comprising: a line attribute determining unit that determines an image attribute of the first line group based on a determination result by the block attribute determining unit.   2. The linearity correction unit according to claim 1, wherein the linearity correction means sets a coefficient for each luminance signal individually for the first luminance signal, and multiplies each luminance signal by the individually set coefficient. Thus, an image processing apparatus comprising coefficient multiplication means for obtaining a second luminance signal having a predetermined luminance level value.   3. The first line group and the first line group according to claim 1 or 2, based on a determination result for the first line group by the line attribute determination unit and a determination result for a predetermined second line group. An image processing apparatus, further comprising final determination means for determining an image attribute of a third line group included in common with the two line groups. The color attribute determination means according to any one of claims 1 to 3,
White pixel determination means for determining whether or not the pixel is a white pixel;
Black pixel determining means for determining whether or not the pixel is a black pixel;
An image processing apparatus comprising: a color pixel determination unit that determines whether or not the pixel is a color pixel.   The image processing apparatus according to claim 4, wherein the white pixel determination unit determines whether or not the pixel is a white pixel by comparing the second luminance signal with a predetermined threshold value.   5. The black pixel determination unit according to claim 4, wherein the black pixel determination means is based on a comparison result between the second luminance signal and a predetermined threshold value, and a comparison value between a difference value between color components of the second luminance signal and a predetermined threshold value. And determining whether or not the pixel is a black pixel. The color pixel determination means according to claim 4,
If the pixel is determined not to be a white pixel by the white pixel determination unit and is determined not to be a black pixel by the black pixel determination unit, the pixel is determined to be a color pixel;
When the corresponding pixel in the previous line in the sub-scanning direction of the line including the color pixel is determined to be a color pixel by the color attribute determination unit, the color attribute of the target pixel is determined as a continuous color pixel, Determining that the color attribute of the target pixel is a single color pixel when the corresponding pixel in the previous line in the sub-scanning direction of the line including the color pixel is not determined to be a color pixel by the color attribute determination unit A featured image processing apparatus. The storage means according to claim 7,
Line holding means for holding color attributes for each pixel for a predetermined line in the color multi-valued image;
Window storage means for storing, in a window format, a color attribute for each pixel of the line held by the line holding means and a color attribute for each pixel of the next line in the sub-scanning direction of the line; A featured image processing apparatus. The window storage means according to claim 8,
First window storage means for storing color attributes for each pixel in a first window format in which the main scanning direction is M (M is a positive integer) pixels and the sub-scanning direction is two pixels;
Second window storage means for storing color attributes for each pixel in a second window format in which the main scanning direction is N (N is a positive integer) pixels and the sub-scanning direction is two pixels. A featured image processing apparatus. The first counting means according to claim 9,
In the first window storage means, the number of windows when the pixel of interest is a color pixel and at least one black pixel is adjacent to the pixel of interest is counted for each second block. First sequence attribute counting means for obtaining the number of sequence attributes;
In the second window storage means, the number of windows when the color pixels are continuous in the vertical direction in the window area excluding the four pixels at both ends and there are no black pixels in the window area including the four pixels at both ends is the number of windows. Second sequence attribute counting means for counting every two blocks to obtain a second sequence attribute number;
In the second window storage means, the number of windows when the continuous color pixel exists in a window region having a main scanning direction of I pixels and a sub scanning direction of 2 pixels is counted for each second block. Third sequence attribute counting means for obtaining a sequence attribute number of 3,
In the first window storage means, the number of windows when the target pixel is a color pixel and no black pixel exists around the color pixel is counted for each second block, and a fourth array attribute is obtained. An image processing apparatus comprising: fourth array attribute counting means for obtaining a number.   11. The fifth array attribute counting unit according to claim 10, wherein the second counting unit counts pixels determined to be black pixels by the black pixel determining unit for each of the second blocks to obtain a black pixel count value. An image processing apparatus comprising: The calculation means according to claim 10,
First computing means for obtaining a first parameter using a ratio between the first array attribute number and the second array attribute number;
An image processing apparatus comprising: a second computing unit that obtains a second parameter using a ratio between the fourth array attribute number and the black pixel count value.   2. The block attribute determination unit according to claim 1, wherein the block attribute determination unit includes a predetermined threshold value for each of the count values obtained by the first and second counting units and the first parameter and the second parameter calculated by the calculation unit. An image processing apparatus, wherein the image attribute of the first block is determined by comparison. The line attribute determining unit according to claim 3, wherein the line attribute determining unit determines whether or not the image attribute of the first line group is monochrome according to the result determined by the block attribute determining unit.
The final determination means determines that the image attribute of the third line group included in common is monochrome when the image attributes of the first line group and the second line group are both determined to be monochrome. An image processing apparatus.   The image processing apparatus according to claim 3, wherein the first line group and the second line group have the same number of lines.   16. The image processing apparatus according to claim 15, wherein the third line group is half the number of lines of the first line group and the second line group.   4. The image processing device according to claim 3, further comprising image processing means for performing image processing on the third line group according to the image attribute of the third line group determined by the final determination means. Image processing device.   5. The image according to claim 4, further comprising image recording means for recording the color multi-valued image in a predetermined line unit, wherein the predetermined line unit has the same number of lines as the third line group. Processing equipment.   19. The image processing apparatus according to claim 18, wherein the image recording unit includes an inkjet monochrome head and a color head, and the monochrome head is longer than the color head. A correction step of correcting a linearity shift of the first luminance signal for each pixel of the color multi-valued image to obtain a second luminance signal;
A color attribute determination step for determining a color attribute for each pixel based on the second luminance signal obtained by the correction in the correction step;
Storing the color attribute determined in the color attribute determination step in a predetermined storage device for pixels in a predetermined area including the target pixel;
The color multi-value image is divided into a first line group composed of a predetermined number of lines in the sub-scanning direction, and the first line group is further divided into a plurality of blocks in the main scanning direction. A second line group consisting of a predetermined number of lines is extracted from the first line group to which it belongs, the array attribute is determined according to the array of color attributes in the storage means, and the number of each array attribute is counted Counting step;
A second counting step of counting the number of pixels having the color attribute determined in the color attribute determining step for the block;
A calculation step of calculating a parameter indicating an image characteristic of the first block based on the count value obtained by the first and second counting steps;
A block attribute determination step of determining an image attribute of the first block according to the count value calculated by the first and second counting steps and the parameter calculated in the calculation step;
A line attribute determination step for determining an image attribute of the first line group based on a determination result obtained by the block attribute determination step.   21. The linearity correction step according to claim 20, wherein the linearity correction step sets a coefficient for each luminance signal individually for the first luminance signal, and multiplies each luminance signal by the individually set coefficient. An image processing method comprising a coefficient multiplying step for obtaining a second luminance signal having a predetermined luminance level value.   23. The first line group and the first line group according to claim 20 or 21, based on a determination result for the first line group in the line attribute determination step and a determination result for a predetermined second line group. An image processing method further comprising a final determination step of determining an image attribute of a third line group included in common with the two line groups. 23. The color attribute determination step according to claim 20, wherein:
A white pixel determination step of determining whether or not the pixel is a white pixel;
A black pixel determination step for determining whether or not the pixel is a black pixel;
And a color pixel determination step of determining whether or not the pixel is a color pixel. The color pixel determination step according to claim 22 or 23,
When it is determined as NO in both the white pixel determination step and the black pixel determination step, the pixel is determined to be a color pixel;
If the corresponding pixel in the previous line in the sub-scanning direction of the line including the color pixel is determined to be a color pixel by the color attribute determination step, the color attribute of the target pixel is determined to be a continuous color pixel, When the corresponding pixel in the previous line in the sub-scanning direction of the line including the color pixel is not determined to be a color pixel by the color attribute determination step, the color attribute of the target pixel is determined to be a single color pixel. A featured image processing method. On the computer,
Based on the first luminance signal for each pixel of the color multi-valued image, a coefficient is individually set for each luminance signal with respect to the first luminance signal, and the individually set coefficient is set for each luminance signal. A coefficient multiplication procedure for obtaining a second luminance signal that is a predetermined luminance level value by multiplying
A color attribute determination procedure for determining a color attribute of the pixel based on the second luminance signal;
A storage procedure for storing the color attributes determined by the color attribute determination procedure in a predetermined storage device for pixels in a predetermined area including the target pixel;
For a second block having a predetermined number of lines in the first block obtained by dividing a predetermined first line group in the color multi-valued image in the main scanning direction, according to the arrangement of the color attributes in the storage device. A first counting procedure for counting the sequence attributes to be determined;
A second counting procedure for counting the color attribute determined by the color attribute determining procedure for the second block;
A calculation procedure for calculating a parameter indicating an image feature of the first block based on the count values obtained by the first and second counting procedures;
A block attribute determination procedure for determining an image attribute of the first block according to the count value by the first and second counting means and the parameter calculated in the calculation procedure;
A line attribute determination procedure for determining an image attribute of the first line group based on a determination result by the block attribute determination procedure;
Common to the first line group and the second line group based on the determination result for the first line group and the determination result for the predetermined second line group by the line attribute determination procedure. The computer program for performing the final determination procedure which determines the image attribute of the 3rd line group contained. The computer-readable recording medium which recorded the computer program of Claim 25.

Images