JP2008271488A - Image processing method, image processing apparatus, image forming apparatus, image reading apparatus, computer program, and recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image processing method, an image processing apparatus, an image forming apparatus, an image reading apparatus, a computer program, and a recording medium in which image processing is performed by discriminating the feature of a pixel per line. <P>SOLUTION: After initialization is performed (S11), an available image area is recognized from information, including a read start position and a read end position of a document, a scaling for performing image processing, a processing object position, or the like (S12). Subsequently, the number of chromatic pixels of one line is counted to output it to a memory (S16), and when it is summed up to an end line of the available image area (S17:YES), a difference between a count number N1 in one previous line of the available image area and a count number N2 in the end line of the available image area is calculated (S19) to thereby compare the difference with a predetermined threshold value (S20). When the difference is larger than the threshold (S20:YES), it is determined to be a chromatic image (S21), whereas when the difference is smaller than the threshold (S20:NO), it is determined to be an achromatic image (S22). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an image processing method, an image processing apparatus, an image forming apparatus, an image reading apparatus, a computer program, and a recording medium that perform image processing by determining pixel attributes in units of lines.

  In an image forming apparatus such as a digital copying machine or a digital multi-function peripheral, an automatic color selection process is performed to determine whether these originals are color originals or monochrome originals in order to perform image processing using an image processing method suitable for each read original. (Hereinafter, it is described as ACS processing (ACS: Auto Color Selection)) (see, for example, Patent Document 1).

  Conventionally, it is determined whether each pixel is a color pixel or a monochrome pixel, and when the presence of a predetermined number or more of continuous color pixels in the given pixel order is detected, the continuous color pixel portion is detected as a color block. If a predetermined number or more of color blocks exist in one line, the line is counted as a color line. If a predetermined number of color lines exist in the document, it is determined as a color image. Otherwise, it is determined as a monochrome image.

  Such an ACS process may be performed differently depending on whether it is performed on the entire area or on a partial area of the read document. Therefore, the ACS process is performed on the effective image area corresponding to the output image area. It is desirable to perform ACS processing only.

  29 and 30 are explanatory diagrams for explaining an example in which the determination result differs depending on the effective image area. FIG. 29 shows an example in which ACS processing is performed on the entire document with respect to a document having monochrome pixels and color pixels. It has color pixels at a rate equal to or greater than the criterion for the number of pixels of the entire document, and is determined to be a color document. The document shown in FIG. 30 is the same as the document shown in FIG. 29, but is an example in the case where ACS processing is performed only on the left half area. Although the entire document has color pixels, since there are no color pixels in the effective image area at a rate equal to or higher than the determination reference, the document is determined to be a monochrome document.

Similarly, there are document determination processing and background color recognition processing as image recognition processing performed only for the effective image area to be output. When performing document determination processing on a document read from a scanner, pre-scanning is performed, and the average value of the difference in the number of pixels in the high density portion between the rising edge and the falling edge of the line image data in the effective image area, The number of pixels in the low density part from the falling to the rising is obtained, and it is determined whether or not it is a character pixel by obtaining the feature amount that is the sum of the average values of the differences in the number of pixels in the adjacent low density parts. There is a method of recognizing a character original if the character pixels are present at a ratio equal to or higher than a certain threshold with respect to the total number of pixels, and a photo original if not (see, for example, Patent Document 2).
JP-A-4-282968 JP 2002-125121 A

  However, the ACS determination process described in Patent Document 1 and the document determination process described in Patent Document 2 both place an original on a document table, read the image data of the entire original, and perform ACS determination and original type determination. This is a process that assumes this. For example, when considering processing by reading a document line by line with an automatic document feeder, the effective image area of the document is determined when the trailing edge of the document is detected. There is a problem in that the ACS process and the document type determination cannot be started until after confirmation.

  FIG. 31 is an explanatory diagram for explaining processing when a document is read line by line by the automatic document feeder. When a document is read by a line scanner equipped with an automatic document feeder, in order to make a region CDEF corresponding to a specific pixel width y from the rear end in the sub-scanning direction of the scan as an effective image region, A position and a specific pixel width y are required. Since y is calculated from the output image size, magnification, etc., it can be determined before reading the document. However, the area CDEF cannot be determined until the trailing edge of the document is detected by the document edge detection sensor of the line scanner. That is, it is necessary to store the read data at least until the rear end is determined in a memory or the like, read the image data from the memory again after the determination, and perform ACS processing only on the effective image area. have.

  The present invention has been made in view of such circumstances, and calculates a difference between feature amounts calculated from a line immediately before a set region and a line at the rear end of the set region, and determines an attribute of the region based on the calculated difference. An image processing method, an image processing apparatus, an image forming apparatus, and an image that can start recognition processing without discriminating and performing processing according to the determination result without accumulating pre-scan or image data in a memory. An object is to provide a reading device, a computer program, and a recording medium on which the computer program is recorded.

  The image processing method according to the present invention is an image processing method for determining an attribute of an image and performing processing according to the determination result. The image to be determined is sequentially read for each line composed of a plurality of pixels, and the read line is configured. Calculating the feature amount representing the feature of the pixel to be determined, determining the attribute of the pixel based on the calculated feature amount, counting the pixels for which the attribute has been determined, and setting a region to be processed for the image, Calculate the difference in the number of pixels for which the attribute is calculated from each of the line immediately before and the line at the rear end of the set area, determine the attribute of the area based on the calculated difference, and according to the determination result The processing is performed on the image in the region.

  According to the present invention, even if the sub-scanning direction size of an image is unknown at the start of image data input, the recognition process can be started without pre-scanning or storing image data in a memory. In addition, when re-summarizing the discrimination results corresponding to the image area set after the image size is determined (when image data input is completed), it is possible to re-aggregate compared to the case where the summation results for only the corresponding line are saved for each line. The amount of processing related to the aggregation process is reduced.

  The image processing method according to the present invention is an image processing method for determining an attribute of an image and performing processing according to the determination result. The image to be determined is sequentially read for each line composed of a plurality of pixels, and the read line is configured. Calculating the feature amount representing the feature of the pixel to be determined, determining the attribute of the pixel based on the calculated feature amount, counting the pixel for which the attribute has been determined for each column divided in the main scanning direction, and For each column included in the set area, the area to be processed is set, and the difference in the number of pixels for which the attribute is calculated from each of the line immediately before and after the set area is determined. The attribute of the region is determined based on the calculated sum of differences for each column, and processing according to the determination result is performed on the image in the region.

  In the present invention, in order to obtain the determination result by dividing also in the main scanning direction, after the image data is temporarily stored in the hard disk or the like, the effective image area is changed again using the stored image data. When processing is performed (for example, when frame erasing processing is performed), recognition processing for a newly set effective image area can be performed.

  The image processing method according to the present invention is an image processing method for determining an attribute of an image and performing processing according to the determination result. The image to be determined is sequentially read for each line composed of a plurality of pixels, and the read line is configured. Calculating a feature amount representing the feature of the pixel to be detected, discriminating the attribute of the pixel based on the calculated feature amount, and determining the attribute for each of a plurality of effective image areas preset in the main scanning direction Counting and setting the area to be processed for the image, and the pixel for which the attribute calculated from each of the immediately preceding line and the trailing line of the set area is determined for the counting result corresponding to the set area The difference between the numbers is calculated, the attribute of the area is determined based on the calculated sum of the differences, and processing according to the determination result is performed on the image in the area.

  In the present invention, when the number of effective image areas is smaller than the number of necessary columns, it is possible to reduce the amount of memory necessary for storing the counting results.

  An image processing apparatus according to the present invention, in an image processing apparatus that determines an attribute of an image and performs processing according to the determination result, means for sequentially reading an image to be determined for each line composed of a plurality of pixels, A feature amount representing a feature of the pixels constituting the image, a means for determining the attribute of the pixel based on the calculated feature amount, a means for counting the pixels for which the attribute has been determined, and processing the image Means for setting the power region, means for calculating the difference in the number of pixels for which the attribute is calculated from each of the line immediately before and the line at the rear end of the set region, and based on the calculated difference, And a means for discriminating the characteristics, and a means for performing processing on the image in the region according to the discrimination result by the means.

  According to the present invention, even if the sub-scanning direction size of an image is unknown at the start of image data input, the recognition process can be started without pre-scanning or storing image data in a memory. In addition, when re-summarizing the discrimination results corresponding to the image area set after the image size is determined (when image data input is completed), it is possible to re-aggregate compared to the case where the summation results for only the corresponding line are saved for each line. The amount of processing related to the aggregation process is reduced.

  An image processing apparatus according to the present invention, in an image processing apparatus that determines an attribute of an image and performs processing according to the determination result, means for sequentially reading an image to be determined for each line composed of a plurality of pixels, Means for calculating the feature amount representing the feature of the pixel constituting the pixel, and determining the attribute of the pixel based on the calculated feature amount, and counting the pixel for which the attribute has been determined for each column divided in the main scanning direction Means for setting the area to be processed for the image, and the difference between the number of pixels for which the attribute is calculated from the line immediately before and the line at the rear end of the set area. Means for calculating for each column included in the data, means for determining the characteristics of the set region based on the calculated sum of differences for each column, and setting the processing according to the determination result by the means. Characterized in that it comprises a means for performing the image in the region.

  In the present invention, in order to obtain the determination result by dividing also in the main scanning direction, after the image data is temporarily stored in the hard disk or the like, the effective image area is changed again using the stored image data. When processing is performed (for example, when frame erasing processing is performed), recognition processing for a newly set effective image area can be performed.

  An image processing apparatus according to the present invention includes means for discriminating features for a plurality of areas, means for storing discrimination results discriminated for the plurality of areas, and processing corresponding to the discrimination results in each area. And means for applying to the image.

  In the present invention, the determination result for the effective image area is obtained, and only the determination result is stored, so that the data amount can be reduced as compared with the case of storing the number of pixels determined in line units. Can do.

  An image processing apparatus according to the present invention, in an image processing apparatus that determines an attribute of an image and performs processing according to the determination result, means for sequentially reading an image to be determined for each line composed of a plurality of pixels, Means for calculating the feature amount representing the feature of the pixel constituting the pixel, and determining the attribute of the pixel based on the calculated feature amount, and a plurality of valid pixels set in advance in the main scanning direction for which the attribute is determined Calculated from each of the means for counting for each image area, means for setting the area to be processed for the image, and the lines immediately before and after the set area for the count result corresponding to the set area Means for calculating the difference in the number of pixels for which the attribute has been determined, means for determining the characteristics of the set region based on the sum of the calculated differences, and processing according to the determination result by the means Characterized in that it comprises a means for performing the image of the serial area.

  In the present invention, when the number of effective image areas is smaller than the number of necessary columns, it is possible to reduce the amount of memory necessary for storing the counting results.

  The image processing apparatus according to the present invention includes means for discriminating features for a plurality of effective image areas, means for storing discrimination results discriminated for the plurality of effective image areas, and a stored discrimination result. It is characterized by comprising means for determining which discrimination result to use, and means for performing processing according to the determined discrimination result on the image in the region.

  In the present invention, the determination result for the effective image area is obtained, and only the determination result is stored, so that the data amount can be reduced as compared with the case of storing the number of pixels determined in line units. Can do.

  The image processing apparatus according to the present invention is characterized in that the attribute of the pixel is chromatic or achromatic of the pixel.

  In the present invention, it is determined whether or not the image to be determined is a chromatic image by taking the difference between the feature amounts calculated from the immediately preceding line and the trailing end line of the set area. The

  The image processing apparatus according to the present invention includes means for comparing the difference between the number of pixels determined to be chromatic and a predetermined value, and the difference between the number of pixels determined to be chromatic is greater than the predetermined value. In this case, it is determined that the image is a chromatic image, and when the difference is smaller than the predetermined value, it is determined that the image is an achromatic image.

  In the present invention, the efficiency of the chromatic / achromatic determination process of the image is improved by starting the determination process before the effective image area is determined, and recounting after the effective image area is determined.

  The image processing apparatus according to the present invention is characterized in that the attribute of the pixel is a region separation result indicating which of the plurality of regions including the character region and the dot region.

  In the present invention, by determining the difference between the feature amounts calculated from the immediately preceding line and the trailing end line of the set area, the image to be determined is a character / halftone image, or the background It is determined whether the image is a photographic paper image.

  The image processing apparatus according to the present invention includes means for comparing the difference between the number of pixels for each region to which the pixel belongs and a predetermined value provided for each region, and the difference in the number of pixels for each region is the region. The document type is discriminated based on a comparison with a predetermined value provided for each.

  According to the present invention, the efficiency of the document type determination process is improved by starting the determination process before the effective image area is determined and re-counting after the effective image area is determined.

  The image processing apparatus according to the present invention is characterized in that the attribute of the pixel is a determination result of whether or not the pixel is a ground region.

  In the present invention, the background color of the image to be determined is determined by taking the difference between the feature amounts calculated from the immediately preceding line and the trailing end line of the set area.

  The image processing apparatus according to the present invention is characterized by comprising means for comparing the difference between the count value of the class value to which the pixel belongs and a predetermined value, and determining the background based on the comparison result. To do.

  In the present invention, the efficiency of the background determination process is improved by starting the discrimination process before the effective image area is determined and re-counting after the effective image area is determined.

  An image processing apparatus according to the present invention, in an image processing apparatus that determines an attribute of an image and performs processing according to the determination result, means for sequentially reading an image to be determined for each line composed of a plurality of pixels, Means for calculating a plurality of feature amounts representing the characteristics of the pixels constituting the image, and determining a plurality of attributes of the pixel based on the calculated plurality of feature amounts; and means for counting the pixels for which the attributes have been determined, Means for setting an area to be processed with respect to the image; means for calculating a difference between the number of pixels for which the respective attributes are determined, calculated from each of a line immediately before and a line at the rear end of the set area; The apparatus comprises: means for discriminating a plurality of features of the area based on the calculated difference; and means for performing processing on the image in the area according to a discrimination result by the means.

  In the present invention, the efficiency of the determination process can be improved even when the above-described auto color selection process, document type determination process, and background determination process are combined.

  An image forming apparatus according to the present invention includes the image processing apparatus according to any one of the above-described inventions, and a unit that forms an image subjected to image processing by the image processing apparatus on a sheet. And

  In the present invention, it can be used as a function of a printer device or a digital multifunction peripheral.

  An image reading apparatus according to the present invention includes means for reading an image from a document, and the image processing apparatus according to any one of the above-described inventions that determines an attribute of the read image and performs processing according to the determination result. It is characterized by providing.

  In the present invention, it can be used as one function of a scanner device or a digital multifunction peripheral.

  A computer program according to the present invention is a computer program that causes a computer to determine an attribute of an image and perform processing according to the determination result. The computer is characterized by the characteristics of pixels constituting the line from a line composed of a plurality of pixels. A step of calculating a feature amount to be represented; a step of causing a computer to determine a pixel attribute based on the calculated feature amount; and a step of counting the pixels for which the attribute has been determined; and A step of setting an area; a step of causing a computer to calculate a difference in the number of pixels in which an attribute is determined based on each of a line immediately before and a rear end line of the set area; and The attribute of the area is discriminated based on the difference, and processing according to the discrimination result is performed in the area. Characterized by a step for performed on the image.

  In the present invention, the above-described image processing apparatus is realized by a computer.

  A recording medium according to the present invention is a computer-readable recording medium on which a computer program for determining an attribute of an image and performing processing according to the determination result is recorded. The computer includes a plurality of pixels. A step of calculating a feature amount representing a feature of a pixel constituting the line from the line, a step of causing a computer to determine the attribute of the pixel based on the calculated feature amount, and counting the pixels for which the attribute has been determined. A step of causing the computer to set an area to be processed for the image; and a difference between the number of pixels for which the attribute is calculated from each of the immediately preceding line and the trailing edge line of the set area. And having the computer determine the attribute of the region based on the calculated difference, and Wherein the computer program is recorded and a step for subjected to processing corresponding to the image of the region to.

  In the present invention, the above-described image processing apparatus is realized by a computer by an image processing program read from a recording medium.

  According to the present invention, the recognition process can be started without pre-scanning or storing image data in the memory even if the size of the image in the sub-scanning direction is unknown at the start of image data input. In addition, when re-summarizing the discrimination results corresponding to the image area set after the image size is determined (when image data input is completed), it is possible to re-aggregate compared to the case where the summation results for only the corresponding line are saved for each line. It is possible to reduce the amount of processing related to the aggregation processing.

  In the case of the present invention, in order to obtain the determination result by dividing also in the main scanning direction, after the image data is temporarily stored in the hard disk or the like, the stored image data is used to change the effective image area and process again. When performing (for example, performing frame erasing processing), recognition processing for a newly set effective image region can be performed.

  According to the present invention, when the number of effective image areas is smaller than the number of necessary columns, the amount of memory necessary for storing the counting results can be reduced.

  In the case of the present invention, the determination result for the effective image area is obtained, and only the determination result is stored, so that the data amount can be reduced as compared with the case of storing the number of pixels determined in line units. it can.

  According to the present invention, it is determined whether or not the image to be determined is a chromatic image by taking the difference between the feature amounts calculated from the immediately preceding line and the trailing end line of the set area. Can do.

  According to the present invention, it is possible to improve the efficiency of the document type determination process by starting the determination process before the effective image area is determined and re-counting after the effective image area is determined.

  In the case of the present invention, the difference between the feature amounts calculated from the immediately preceding line and the trailing edge line of the set area is taken, so that the image to be determined is a character / halftone dot image or a background / It is possible to determine whether the image is a photographic paper image.

  According to the present invention, the background color of the image to be determined can be determined by taking the difference between the feature amounts calculated from the immediately preceding line and the trailing end line of the set area.

  According to the present invention, it can be used as a function of a printer device or a digital multi-function peripheral.

  According to the present invention, it can be used as a function of a scanner device or a digital multifunction peripheral.

  In the case of the present invention, the above-described image processing apparatus can be realized by a computer.

  According to the present invention, the above-described image processing apparatus can be realized by a computer by an image processing program read from a recording medium.

Hereinafter, the present invention will be specifically described with reference to the drawings showing embodiments thereof.
Embodiment 1 FIG.
FIG. 1 is a block diagram illustrating an internal configuration of an image processing system including an image processing apparatus according to the present invention. The image processing system according to the first embodiment includes an operation panel 1, an image input device 3, an image processing device 5A, and an image output device 7.

  The operation panel 1 includes a liquid crystal display device, various switches, and the like, and accepts display of information to be notified to the user, various selection operations by the user, and the like.

The image input device 3 is a reading unit that optically reads an image of a document, and includes a light source that irradiates light to a document for reading, an image sensor such as a CCD (Charge Coupled Device), and the like.

  FIG. 2 is a schematic diagram showing the configuration of the image input device 3. The image input device 3 includes a document conveying unit configured by an upper casing 510, a scanner unit configured by a lower casing 560, and the like. A document set sensor 514 that detects a document placed on the document tray 511, a call roller 512 for conveying the document one by one, and a document for reading an image on the document are conveyed to the upper casing 510. Conveying rollers 513a and 513b, a document discharge roller 50 for discharging a document, a document discharge sensor 567 for detecting a document to be discharged, and the like are provided. The conveyance roller (alignment roller) 513b includes an electromagnetic clutch (not shown) on the drive shaft, and can control transmission of driving force from a drive motor (not shown), so that there is no document. Then it has stopped. Then, when the leading edge of the document comes into contact with the feeding timing sensor 515 and a predetermined signal is transmitted from this sensor, the document is set to rotate in the direction in which the document is conveyed downstream. The conveyance roller 513b is in a stopped state so that the leading edge of the document conveyed from the upstream side comes into contact with the nip portion of the conveyance roller 513b and forms a predetermined deflection on the document, and then conveys the document downstream. Rotate. At this time, the leading edge of the document is aligned by the nip portion of the conveying roller 513b so as to be perpendicular to the conveying direction.

  The lower housing 560 is provided with scanning units 562 and 563 that reciprocate in parallel along the lower surface of the mounting table 561, an imaging lens 564, a CCD line sensor 565 that is a photoelectric conversion element, a discharge tray 566, and the like. . The scanning unit 562 has a light source 562a (for example, a halogen lamp) for irradiating light on a document conveyed from the document tray 511 or a document placed on the table 561, and light reflected by the document. And a mirror 562b for guiding it to the optical path. The scanning unit 563 also includes mirrors 563a and 563b for guiding the light reflected from the document to a predetermined optical path.

  The imaging lens 564 images the reflected light guided from the scanning unit 563 at a predetermined position on the CCD line sensor 565. The CCD line sensor 565 photoelectrically converts the formed optical image and outputs an electrical signal. That is, based on a color image read from an original (for example, the surface of the original), data (RGB signal) that is color-separated into R (red), G (green), and B (blue) color components is processed by the image processing apparatus 5A. Output to. At this time, the image input device 3 outputs the data read line by line in the sub-scanning direction to the image processing device 5A. Further, as shown in FIG. 3, the image processing apparatus 5A is notified of signals output from the feeding timing sensor 515, that is, a document reading start signal and a reading end signal.

  The image processing device 5 </ b> A converts the analog electrical signal output from the image input device 3 into a digital electrical signal, performs appropriate image processing, and outputs the obtained image data to the image output device 7. The internal configuration and operation of the image processing apparatus 5A will be described in detail later.

  The image output device 7 is means for forming an image on a sheet such as paper or an OHP film based on an image signal output from the image processing device 5A. For this reason, the image output device 7 is a charger for charging the photosensitive drum to a predetermined potential, and laser writing for generating an electrostatic latent image on the photosensitive drum by emitting laser light in accordance with image data received from the outside. An apparatus, a developing device that supplies toner to the electrostatic latent image formed on the surface of the photosensitive drum to make it visible, a transfer device that transfers the toner image formed on the surface of the photosensitive drum onto paper (not shown), etc. And an image desired by the user is formed on a sheet by electrophotography. In addition to image formation by an electrophotographic method using a laser writing apparatus, an image formation may be performed by an inkjet method, a thermal transfer method, a sublimation method, or the like.

  Next, the internal configuration of the image processing apparatus 5A will be described. The AD converter 51 converts RGB analog signals input from the image input device 3 into digital signals. The shading correction unit 52 performs a process of removing various distortions generated in the illumination system, the imaging system, and the imaging system of the image input device 3 on the digital RGB signal output from the AD conversion unit 51. The RGB signal subjected to the shading correction is output to the ACS determination processing unit 53.

  The ACS determination processing unit 53 performs processing for selecting whether the document image is a color image or a monochrome image by using a part of pixels constituting the document image. The processing contents in the ACS determination processing unit 53 will be described in detail later. The determination result in the ACS determination processing unit 53 is the following input gradation correction unit 55, region separation processing unit 56, color correction unit 57, black generation and under color removal unit 58, spatial filter processing unit 59, gradation reproduction processing unit. 62 is output.

  The input tone correction unit 55 performs image quality adjustment processing such as background density removal and contrast. The region separation processing unit 56 performs processing for separating each pixel in the input image into one of a character region, a halftone dot region, and a photographic region from the RGB signals. The region separation processing unit 56 sends a region identification signal indicating which region the pixel belongs to to the subsequent black generation and under color removal unit 58, the spatial filter processing unit 59, and the gradation reproduction processing unit 62 based on the separation result. At the same time, the input RGB signal is output to the subsequent color correction unit 57 as it is.

  The color correction unit 57 performs processing for removing color turbidity based on the spectral characteristics of CMY color materials including unnecessary absorption components in order to faithfully reproduce color reproduction. The color-corrected RGB signal is output to the subsequent black generation and under color removal unit 58. The black generation and under color removal unit 58 generates black (K) signals from the CMY three-color signals after color correction, and generates a new CMY signal obtained by subtracting the K signal obtained by black generation from the original CMY signals. Generate the process. By this processing, the CMY three-color signal is converted into a CMYK four-color signal.

  As an example of the black generation process, there is a method of generating black using skeleton black. In this method, the input / output characteristic of the skeleton curve is y = f (x), the input data is C, M, Y, the output data is C ′, M ′, Y ′, K ′, the UCR rate (UCR) : Under Color Removal) α (0 <α <1), the black generation under color removal processing is expressed by the following equation.

K ′ = f {min (C, M, Y)}
C ′ = C−αK ′
M ′ = M−αK ′
Y ′ = Y−αK ′

  The spatial filter processing unit 59 performs spatial filter processing using a digital filter on the image data of the CMYK signal input from the black generation and under color removal unit 58 based on the region identification signal, thereby correcting the spatial frequency characteristics. Processing is performed to prevent blurring and particulate deterioration of the output image.

  For example, the region separated into characters by the region separation processing unit 56 has a high frequency enhancement amount in the sharp enhancement processing in the spatial filter processing by the spatial filter processing unit 59 in order to improve the reproducibility of black characters or color characters in particular. Increased. At the same time, the gradation reproduction processing unit 62 selects binarization or multi-value processing on a high-resolution screen suitable for high-frequency reproduction. Further, with respect to the region separated into halftone dot regions by the region separation processing unit 56, the spatial filter processing unit 59 performs low pass filter processing for removing the input halftone component. The output tone correction unit 60 performs output tone correction processing for converting a signal such as a density signal into a halftone dot area ratio that is a characteristic value of the color image output device, and then the tone reproduction processing unit 62 performs the final processing. Specifically, gradation reproduction processing is performed in which an image is separated into pixels and processed so that each gradation can be reproduced. In addition, regarding the region separated into photographs by the region separation processing unit 56, binarization or multi-value processing is performed on the screen with an emphasis on gradation reproducibility. Further, the scaling processing unit 61 performs scaling processing as necessary before performing the area reproduction processing.

  The image data subjected to the above-described processes is temporarily stored in storage means (not shown), read at a predetermined timing, and output to the image output device 7.

  Below, the structure of the ACS determination process part 53 is demonstrated. FIG. 4 is a block diagram showing an internal configuration of the ACS determination processing unit 53. The ACS determination processing unit 53 includes a CPU 531, a memory 532, a color pixel determination unit 533, a color pixel count unit 534, and a color document determination unit 535.

  The CPU 531 recognizes the document size from the information of the document reading start position and the reading end position notified from the image input device 3. Further, information such as an enlargement ratio and a processing target position for performing image processing on a document input from the operation panel 1 or the like is acquired and analyzed, and recognized as effective image area information.

  FIG. 5 is an explanatory diagram for explaining an effective image area. For example, when the scaling process is designated, the effective image area is set by setting a target image area in accordance with the set scaling ratio. Alternatively, even when the magnification is set to be equal, when outputting to a paper having a size smaller than the document size, a predetermined output image area is set as an effective image area. For example, when outputting an A3 size document to an A4 size sheet, the right half area (area defined by default) of the A3 size document is set as an effective image area.

  The color pixel determination unit 533 determines whether or not the pixel is a color pixel (or block) in units of pixels (or blocks, for example, blocks composed of 8 × 8 pixels). The result is output to the color pixel count unit 534 as a color pixel flag. Whether the pixel is a color pixel or a monochrome (monochrome) pixel is determined by, for example, a value of max (R, G, B) -min (R, G, B) and a threshold value THcolor_p (for example, a gradation value (8 bits of image data)). In the case of the image data of (5) to (5% to 10%) of 256). When max (R, G, B) -min (R, G, B) is equal to or greater than the threshold value THcolor_p, it is determined that the color is chromatic, and when it is smaller than the threshold value, it is determined that the image is monochrome.

  The color pixel count unit 534 increments (increases) the count number if the color pixel flag input from the color pixel determination unit 533 indicates color, and the count number remains unchanged if it indicates that it is not color. And Each time one line is counted, the current color pixel count is output to the memory 532. At this time, initialization of the counter is performed at the document reading start position, and is not performed for each line unit. The count number of color pixels is always the sum from the document reading start position.

  In the memory 532, the color pixel count is sequentially stored in the memory for each line. Further, the line count requested by the color document determination unit 535 is output to the color document determination unit 535.

  The color original determination unit 535 receives the effective image area information from the CPU 531, and based on this information, the color pixel count number N1 in the previous line of the effective image area and the color pixel count number N2 in the rear end line of the effective image area. (See FIG. 5) is requested to the memory 532. The difference between the two count numbers input from the memory 532 is calculated, the color pixel count number in the effective image area is obtained, the threshold value is compared to determine whether the document is a color document or a monochrome document, and the determination result is output. To do. As the threshold value THcolor_d, for example, the number of pixels having a size of about 1 cm square with respect to the input document is used. Since the value of the threshold THcolor_d differs depending on the resolution of the image input apparatus, it is set according to the resolution. If it is equal to or greater than the threshold THcolor_d, it is determined that the document is a color document, and if it is smaller than the threshold THcolor_d, it is determined that the document is a monochrome document.

  6 and 7 are flowcharts for explaining the procedure of processing executed by the ACS determination processing unit 53. The CPU 531 first initializes the color pixel flag, the count number stored in the memory, and the like (step S11). Then, the document size is recognized from the information on the reading start position and the reading end position of the document notified from the image input device 3, and the enlargement ratio for performing image processing on the document input from the operation panel 1 or the like Information such as the processing target position is acquired and analyzed, and recognized as effective image area information (step S12).

  Next, the color pixel determination unit 533 determines whether or not the pixel is a color pixel in units of pixels constituting one line (step S13). When it is determined that the pixel is a color pixel (S13: YES), the color pixel count unit 534 increments the counter by 1 (step S14). If it is determined that the pixel is not a color pixel (S13: NO), the counter value is held as it is.

  Next, the CPU 531 determines whether or not the color pixel determination process for one line has been completed (step S15). If it is determined that the color pixel determination process has not been completed (S15: NO), the process returns to step S13.

  When it is determined that the color pixel determination process for one line has been completed (S15: YES), the color pixel count unit 534 outputs the number of color pixels (the number of color pixels up to the processed line) to the memory 532 (Step S15). S16). Next, the CPU 531 determines whether or not it is the rear end line of the effective image area (step S17). If it is determined that it is not the rear end line (S17: NO), the next line is processed (step S18). The process returns to step S13.

  When it is determined that the current line is the rear end line of the effective image area (S17: YES), the color document determination unit 535 determines the color pixel count N1 and the effective image area in the line immediately before the effective image area. A difference from the color pixel count number N2 in the rear end line is calculated (step S19), and it is determined whether or not the difference (N2−N1) is greater than or equal to a threshold value THcolor_d (step S20). When it is determined that the difference (N2-N1) is equal to or greater than the threshold THcolor_d (S20: YES), it is determined that the document image is a color image (step S21), and the difference (N2-N1) is determined to be smaller than the threshold THcolor_d. If so (S20: NO), it is determined that the document image is a monochrome (monochrome) image (step S22).

  In the present embodiment, the color original determination unit 535 performs the process of determining whether the original is a color original or a black and white original from the line-unit count. However, the CPU 531 may be configured to perform the process. FIG. 8 is a block diagram showing a modification of the ACS determination processing unit 53.

  As described above, in the present embodiment, the data stored in the memory 532 is the color pixel cumulative count number in units of lines, and thus can be realized with a smaller memory size than that for storing image data. In addition, since color pixel determination, color pixel count, and storage in memory are performed in parallel with document scanning, the only necessary processing after scanning is to determine whether the document is a color document by taking out two values from the memory. Even if an effective image area exists in any position in the document, it is possible to perform the ACS processing at a high speed with almost no time loss.

Embodiment 2. FIG.
The determination result may be sequentially added for each column (row) set in advance in the main scanning direction. In such a configuration, even when the effective image area is changed by the setting at the time of reprocessing, the attribute determination according to the setting can be performed.

  The apparatus configuration is the same as in the first embodiment, and the document is read line by line in the sub-scanning direction by the image input apparatus 3 and input to the color pixel determination unit 533 of the ACS determination processing unit 53. Further, the image input device 3 is provided with a feeding timing sensor 515, and notifies the CPU 531 of the reading start position and the reading end position of the document.

  The CPU 531 recognizes the document size from the information of the document reading start position and the reading end position notified from the image input device 3. Also, information such as an enlargement ratio and a processing target position for performing image processing on a document input from the operation panel 1 or a host computer not shown in the figure is acquired and analyzed, and a color document as effective image area information The determination unit 535 is notified.

  As for the effective image area, for example, when a scaling process is designated, a target image area is set according to the set scaling ratio. Alternatively, even when the magnification is set to be equal, when outputting to a sheet having a size smaller than the original size, a predetermined output image area is set as an effective image area. 9 and 10 are schematic diagrams showing examples of setting an effective image area. For example, when an A3 size document is output on A4 size paper, the right half area (area defined by default) of the A3 size document is set as an effective image area (FIG. 9). Also, an area designated as an area other than the frame by a function such as frame erasing is set as an effective image area (FIG. 10). That is, in FIG. 10, the area other than the effective image area is shown as a frame.

  The color pixel determination unit 533 determines whether the input image data is a color pixel in units of pixels. The determination result of the color pixel determination unit 533 is output to the color pixel count unit 534 as a color pixel flag. Whether the pixel is a color pixel or a monochrome (monochrome) pixel is determined by, for example, a value of max (R, G, B) -min (R, G, B) and a threshold value THcolor_p (for example, a gradation value (8 bits of image data)). In the case of the image data of (5) to (5% to 10%) of 256). When max (R, G, B) -min (R, G, B) is equal to or greater than the threshold value THcolor_p, it is determined that the color is chromatic, and when it is smaller than the threshold value, it is determined that the image is monochrome (achromatic). .

  The color pixel counting unit 534 counts color pixels for each column of image data set in advance. FIG. 11 is a schematic diagram showing an example of column division. The example of FIG. 11 shows a state in which the input image is divided into five columns 10A to 10E in the main scanning direction, and color pixels are counted for each of the five columns 10A to 10E. That is, if the color image flag input from the color pixel determination unit 533 indicates that it is color, the count number is incremented by 1, and if it indicates that it is not color, the count number remains unchanged. Each time one line is counted, the current color pixel count is output to the memory 532. At this time, initialization of the counter is performed at the document reading start position, and is not performed for each line unit. The count number of color pixels is always the sum from the original reading start line.

  Note that the method of dividing into columns is determined by a mode selected at the time of scanning and a mode selectable at the time of reprocessing (for example, a frame erasing mode). 12 to 14 are schematic diagrams showing examples of setting an effective image area. For example, in the frame erasing mode or the like, when the patterns of FIGS. 12 to 14 are displayed on a display device such as a liquid crystal display so that the effective image areas 11 to 13 can be selected, the column is divided into five. . Alternatively, a column pattern (for example, division for each predetermined block (for example, a block composed of 7 × 7 pixels)) may be determined in advance. How to divide may be determined in advance by using various image samples and determining a pattern that can be appropriately processed when reprocessing.

  In the memory 532, the color pixel count number for each column is sequentially stored in line units. The schematic diagram of FIG. 15 shows an example of storing the color pixel count number in the memory 532. The memory 532 outputs the line count requested by the color pixel determination unit 533 to the color document determination unit 535.

  The color original determination unit 535 receives the effective image area information from the CPU 531, and based on this information, the color pixel count number N1 in the line immediately before the effective image area of the corresponding column and the color in the rear end line of the effective image area. The pixel count number N 2 is requested to the memory 532. The difference between the two count numbers input from the memory 532 is calculated, the color pixel count number in the effective image area is obtained, the threshold value is compared to determine whether the document is a color document or a monochrome document, and the determination result is output. To do. As the threshold value THcolor_d, for example, the number of pixels having a size of about 1 cm square with respect to the input document is used. Since the value of the threshold THcolor_d differs depending on the resolution of the image input device 3, it is set according to the resolution. For example, when the resolution is 1200 dpi, the value is set to about THcolor_d = 24000. If it is equal to or greater than the threshold THcolor_d, it is determined that the document is a color document, and if it is smaller than the threshold THcolor_d, it is determined that the document is a monochrome document.

  Regarding the totaling of the effective image areas 11 to 13, when the count number in units of lines is stored for each column as shown in FIG. 15, the totaling is performed according to the following formula.

  Color pixel count in effective image area 11 = N (A, n) + N (B, n) + N (C, n) + N (D, n) + N (E, n)

  Color pixel count in effective image area 12 = N (B, b) -N (B, a-1) + N (B, d) -N (B, c-1) + N (C, b) -N (C , A-1) + N (C, d) -N (C, c-1) + N (D, b) -N (D, a-1) + N (D, d) -N (D, c-1)

  Number of color pixel counts in the effective image area = N (B, b) −N (B, a−1) + N (B, d) −N (B, c−1) + N (D, b) −N (D , A-1) + N (D, d) -N (D, c-1)

  In the above formula, a to d and n represent the lines shown in FIGS. 13 and 14, A to E represent the columns shown in FIG. 15, and N represents the number of pixels counted in each column of the lines up to a certain line. Represents.

  In the above example, the number of color pixels is totalized for the entire document. However, in the case of the effective image area 12 and the effective image area 13, the count number may be totalized for each divided effective image area. For example, the two effective image areas 12A and 12B obtained by dividing the effective image area 12 are as follows.

  Color pixel count in effective image area 12A = N (B, b) -N (B, a-1) + N (C, b) -N (C, a-1) + N (D, b) -N (D , A-1)

  Color pixel count in effective image area 12B = N (B, d) −N (B, c−1) + N (C, d) −N (C, c−1) + N (D, d) −N (D , C-1)

  Hereinafter, the content of the process performed using the determination result for every column is demonstrated. FIG. 16 is a flowchart for explaining a processing procedure during document reading. When scanning of a document is started and image data to be processed is input, the ACS determination processing unit 53 obtains a determination result line by line for each column using the above-described method (step S101). Then, it is determined whether or not print processing is requested according to the settings at the time of reading the original (step S102).

  When it is determined that the printing process is requested (S102: YES), the color pixel count is added up for each set effective image area, and the determination result for the effective image area is obtained (step S103). Then, image processing based on attribute discrimination is performed (step S104), and printing processing is executed (step S105).

  If it is determined in step S102 that printing processing is not requested (S102: NO), it is determined whether filing processing is requested according to the setting at the time of document reading (step S106).

  If it is determined that the filing process is requested (S106: YES), the image data and the determination result are stored in an HDD or the like not shown (steps S107 and S108). If it is determined in step S106 that the filing process is not requested (S106: NO), the process according to this flowchart is terminated.

  FIG. 17 is a flowchart for explaining the processing procedure during reprinting. First, a determination result for the effective image area is obtained according to the setting at the time of reprinting (step S111), and image processing based on attribute determination is performed (step S112). Next, print processing is executed based on the image processed image (step S113).

  In the present embodiment, the color original determination unit 535 performs the process of determining whether the original is a color original or a black and white original from the line-unit count. However, the CPU 531 may be configured to perform the process. The configuration of the ACS determination processing unit 53 in this case is the same as that shown in FIG.

Embodiment 3 FIG.
The method described below can also be used as a method of generating and counting the count number in units of lines.

  The color pixel counting unit 534 sets the count number to 1 if each color image flag input from the color pixel determination unit 533 indicates color for each effective image area of the preset image data. If it is incremented and indicates that it is not a color, the count is left as it is. Each time one line is counted, the current color pixel count is output to the memory 532. At this time, initialization of the counter is performed at the document reading start position, and is not performed for each line unit. The count number of color pixels is always the sum from the original reading start line.

  The effective image area is determined by a mode selected at the time of scanning and a mode selectable at the time of reprocessing. If it is assumed that the modes of the effective image areas 11 to 13 as shown in FIGS. 12 to 14 can be selected, the counts in units of lines for the three effective image areas are set in parallel as shown in FIG. It is generated and stored in the memory 532.

  In the memory 532, the color pixel count is sequentially stored in units of lines. Further, the line count requested by the color pixel determination unit 533 is output to the color document determination unit 535.

  The color original determination unit 535 receives the effective image area information from the CPU 531, and based on this information, the color pixel count number in the line immediately before the corresponding effective image area and the color pixel count number in the rear end line of the effective image area. To the memory 532. The difference between the two count numbers input from the memory 532 is calculated, the color pixel count number in the effective image area is obtained, the threshold value is compared to determine whether the document is a color document or a monochrome document, and the determination result is output. To do. As the threshold value THcolor_d, for example, the number of pixels having a size of about 1 cm square with respect to the input document is used. Since the value of the threshold THcolor_d differs depending on the resolution of the image input apparatus, it is set according to the resolution. If it is equal to or greater than the threshold THcolor_d, it is determined that the document is a color document, and if it is smaller than the threshold THcolor_d, it is determined that the document is a monochrome document.

  Regarding the totaling of the effective image areas 11 to 13, for example, when the number of counts in units of lines is stored as shown in FIG. 18, the totaling is performed according to the following formula.

Color pixel count in effective image area 11 = N (Reg1, n)
Color pixel count in effective image area 12 = N (Reg2, b) −N (Reg2, a−1) + N (Reg2, d) −N (Reg2, c−1)
Color pixel count in effective image area 13 = N (Reg3, b) -N (Reg3, a-1) + N (Reg3, d) -N (Reg3, c-1)

  In the present embodiment, the color original determination unit 535 performs the process of determining whether the original is a color original or a black and white original from the line-unit count. However, the CPU 531 may be configured to perform the process. The configuration of the ACS determination processing unit 53 in this case is the same as that shown in FIG.

  In the above description, an example of determining whether the original is a color original or a black and white original is shown. However, the present invention may be applied to an original type determination process and a background determination process, which will be described later, or a combination of the above processes. You may make it apply to.

Embodiment 4 FIG.
FIG. 19 is a block diagram illustrating an internal configuration of an image processing system including the image processing apparatus according to the present embodiment. The image processing system according to the fourth embodiment includes an operation panel 1, an image input device 3, an image processing device 5B, and an image output device 7. The configuration other than the image processing device 5B is exactly the same as that of the first embodiment, and a description thereof will be omitted.

  The image processing device 5B includes a document type determination unit 54 instead of the ACS determination processing unit 53 of the image processing device 5A described in the first embodiment. FIG. 20 is a block diagram showing the internal configuration of the document type determination unit 54. The document type determination unit 54 includes a CPU 541, a memory 542, a feature amount calculation unit 543, a discrimination result totaling unit 544, and a document determination unit 545.

  The feature amount calculation unit 543 calculates feature amounts for determining the attributes of the document such as the degree of complexity and the number of inversions of the input image data in pixel units (or block units), and discriminates pixels by threshold processing or the like. The discrimination result is output to the discrimination result totaling unit 544. One or more determination results may be generated by the feature amount calculation unit 543. For example, if the degree of congestion with respect to the 7 × 7 mask is equal to or greater than the threshold value, a character candidate pixel is output. Otherwise, a determination result indicating that the pixel is not a character candidate pixel is output. The determination result may be output as a background candidate pixel, and if not, it is not a background candidate pixel.

  The discrimination result totaling unit 544 increments the count by 1 for each discrimination result input from the feature amount calculation unit 543. At this time, the value of the discrimination result itself may be added as the count number, or a value obtained by data compression of the discrimination result (for example, a quantized value or a logarithmic transformation value) may be added as the count number. Each time one line is counted, the determination result count number up to the present is output to the memory unit. At this time, initialization of the counter is performed at the document start position, and is not performed for each line unit. Always the sum from the document reading start position.

  The memory 542 sequentially stores the discrimination result count number in the memory in units of lines. Further, the count number of lines requested by the document determination unit 545 is output to the document determination unit 545. The document determination unit 545 receives the effective image area information from the CPU 541, and based on this information, the memory 542 stores the determination result count number in the previous line of the effective image area and the determination result count number in the rear end line of the effective image area. To request. The difference between the two count numbers input from the memory 542 is calculated, the discrimination result count number in the effective image area is obtained, the threshold comparison is performed to determine what kind of document is the document, and the determination result is Output.

  For the determination of the document type, a determination method described in Japanese Patent Application Laid-Open No. 2002-232708 can be used. FIG. 21 is a block diagram showing details of the feature amount calculation unit 543 and the discrimination result totaling unit 544.

  The feature amount calculation unit 543 includes a minimum density value calculation unit 5431, a maximum density value calculation unit 5432, a maximum density difference calculation unit 5433, a total density busyness calculation unit 5434, a determination region setting unit 5435, a maximum density difference threshold setting unit 5435a, A total density busyness threshold setting unit 5435b, a character / halftone determination unit 5436, a character / halftone determination threshold setting unit 5436a, a background / printing paper determination unit 5437, and a background / printing paper determination threshold setting unit 5437a are provided.

  The minimum density value calculation unit 5431 calculates a minimum density value in an n × m block (for example, 5 × 15 pixels) including the target pixel based on the CMY signal converted by a signal conversion unit (not shown), and the maximum density Based on the input CMY signal, the value calculation unit 5432 calculates a maximum density value in an n × m (for example, 5 × 15 pixels) block including the target pixel. The maximum density difference calculator 5433 calculates the maximum density difference using the minimum density value and the maximum density value calculated by the minimum density value calculator 5431 and the maximum density value calculator 5432.

  The total density busyness calculation unit 5434 calculates the sum of absolute values of density differences between adjacent pixels in the main scanning direction and the sub-scanning direction in the n × m (for example, 5 × 15 pixels) block, and performs main scanning. The sum of the direction and sub-scan directions is calculated. The determination area setting unit 5435 is calculated by the maximum density difference calculated by the maximum density difference calculation unit 5433, the threshold for the maximum density difference set by the maximum density difference threshold setting unit 5435a, and the total density busyness calculation unit 5434. Are divided into a background / printing paper (photo) area and a character / halftone dot area on the basis of the threshold values for the total density busyness and the total density busyness threshold set by the total density busyness threshold setting unit 5435b.

  The character / halftone dot determination unit 5436 determines whether the pixel in the region separated into the character / halftone dot region by the determination region setting unit 5435 is a character or a halftone dot. For the determination, a threshold set by the character / halftone determination threshold setting unit 5436a is used. The result is output to the discrimination result totaling unit 544. The character pixel totaling unit 5441 of the discrimination result totaling unit 544 totals the pixels determined to be characters, and the halftone pixel totaling unit 5442 totals the pixels determined to be halftone dots.

  The background / photographic paper determination unit 5437 determines whether the pixel in the region separated into the background / printing paper region by the determination region setting unit 5435 is a background or photographic paper (photographic paper photograph). For the determination, a threshold set by the background / photographic paper determination threshold setting unit 5437a is used. The result is output to the discrimination result totaling unit 544. The background pixel counting unit 5322 counts the pixels determined as the background, and the photographic paper pixel counting unit 5323 counts the pixels determined as the photographic paper.

  FIG. 22 is a flowchart for explaining a procedure of processing executed by the document type determination unit 54. The CPU 541 first initializes the count number stored in the memory (step S31). Then, the document size is recognized from the information on the reading start position and the reading end position of the document notified from the image input device 3, and the enlargement ratio for performing image processing on the document input from the operation panel 1 or the like Information such as the processing target position is acquired and analyzed, and recognized as effective image area information (step S32).

  Next, the feature amount calculation unit 543 calculates a feature amount in units of pixels constituting one line (step S33), and determines pixel attributes (step S34). Then, the counter value is incremented by one according to the determination result (step S35), and it is determined whether or not the processing for one line is completed (step S36). If it is determined that the process for one line has not been completed (S36: NO), the process returns to step S33.

  If it is determined that the processing for one line has been completed (S36: YES), the determination result (the determination result up to the processed line) is output to the memory 542 (step S37). Next, the CPU 541 determines whether or not it is the rear end line of the effective image area (step S38). If it is determined that it is not the rear end line (S38: NO), the next line is processed (step S39). The process returns to step S33.

  When it is determined that the current line is the rear end line of the effective image area (S38: YES), the difference (character) between the determination result of the previous line of the effective image area and the determination result of the rear end line of the effective image area (The difference between the number of pixels determined to be halftone dots, the number of pixels determined to be background, the number of pixels determined to be photographic paper) (step S40), and based on the calculated difference The type is determined (step S41). For example, the ratio of the number of pixels in each area to the total number of pixels in the effective image area is obtained, and the effective image is compared with the threshold values set for the character area, halftone area, photographic paper photograph area, and background area The document type of the area is determined. For example, when the ratio between the number of pixels determined to be a character and the number of pixels determined to be a halftone dot is equal to or greater than the respective threshold values, it is determined that the document is a character-printed photographic document.

  The threshold value can be set as follows. For example, assuming that the detection accuracy is higher in the order of characters, halftone dots, and photographic paper photographs, if the ratio of pixels determined to be characters is 30% of the total number of pixels in the effective image area, it is determined as a character document and halftone dots. If the ratio of the detected pixels is 20% of the total number of pixels in the effective image area, the ratio of the pixels determined to be halftone original (printed photo original) and photographic paper photograph is 10% of the total number of pixels in the effective image area. In this case, it is determined that the document is a photographic paper photo original.

  In the present embodiment, the document type is determined by the document determination unit 545, but may be configured by the CPU 541. FIG. 23 is a block diagram showing a modification of the document type determination unit 54.

Embodiment 5. FIG.
In this embodiment, an application example to the background determination process will be described. FIG. 24 is a block diagram showing an internal configuration of the input tone correction unit 55 in the image processing apparatus 5A shown in FIG. The input tone correction unit 55 includes a CPU 551, a memory 552, a histogram processing unit 553, a class value totaling unit 554, and a background determination unit 555.

  The CPU 551 recognizes the document size from the information on the reading start position and the reading end position of the document notified from the image input device 3. Further, information such as an enlargement ratio and a processing target position for performing image processing on a document input from the operation panel 1 or the like is acquired and analyzed, and recognized as effective image area information.

  The histogram processing unit 553 determines which class value is included in the histogram by performing threshold value determination processing on the density value of the input image data in pixel units (or block units), and class values are included in the class value aggregation unit 554. Output to. At this time, a class value determined to be a base is determined in advance, and only the corresponding class value is output to the class value totaling unit 554. That is, background candidate pixels are extracted.

  The class value totaling unit 554 counts the class value of the background candidate pixels input from the histogram processing unit 553, and increments the count corresponding to the input class value by one. Each time one line is counted, the count number for each class is output to the memory 552. At this time, initialization of the counter is performed at the document start position, and is not performed for each line unit. Always the sum from the document reading start position.

  In the memory 552, the count number for each class of the histogram is sequentially stored in the memory 552 in units of lines. Further, the count number of lines requested by the background determination unit 555 is output to the background determination unit 555.

  The background determination unit 555 receives the effective image area information from the CPU 551, and based on this information, the count number for each class value of the histogram in the previous line of the effective image area and each histogram in the rear end line of the effective image area. The memory 552 is requested for the count for the class value. The difference between the two sets of count numbers input from the memory 552 is calculated for each class value to obtain the count number for each class value of the histogram in the effective image area, and is compared with the threshold value for each color component. As a result, the background of the document is determined and the determination result is output. The threshold value for comparing the class value and the count number determined to be the background is determined so that the background can be appropriately extracted using various image samples.

  In the above, only the class values determined to be the background are counted, but all the class values are counted, and the difference of the count values is obtained only for the class values determined to be the background. You may make it perform determination.

  FIG. 25 is a flowchart for explaining the procedure of processing executed by the input tone correction unit 55. First, the CPU 551 initializes the count number stored in the memory (step S51). Then, the document size is recognized from the information on the reading start position and the reading end position of the document notified from the image input device 3, and the enlargement ratio for performing image processing on the document input from the operation panel 1 or the like Information such as the processing target position is acquired and analyzed, and recognized as effective image area information (step S52).

  Next, the histogram processing unit 553 performs processing in units of pixels constituting one line, classifies the pixels into class values for each color component (step S53), and increments the count corresponding to the class value by 1 ( Step S54).

  The CPU 551 determines whether or not the processing for one line has been completed (step S55). If the CPU 551 determines that the processing for one line has not been completed (S55: NO), the process returns to step S53.

  If it is determined that the processing for one line has been completed (S55: YES), the count value count value (the count value count value up to the processed line) is output to the memory 552 for each color component (step S56). . Next, the CPU 541 determines whether or not it is the rear end line of the effective image area (step S57). If it is determined that it is not the rear end line (S57: NO), the next line is processed (step S58). The process returns to step S53.

  When it is determined that the current line is the rear end line of the effective image area (S57: YES), the count value of the class value of the line immediately before the effective image area and the class value of the rear end line of the effective image area The difference between the counts is calculated for each color component (step S59). Then, it is determined that the value of the largest class value (in the case of an RGB signal) among the color components whose count number is equal to or greater than the threshold is the background (step S60). Then, a background removal process is performed based on the background discrimination result.

  For example, the following method described in Japanese Patent Laid-Open No. 2000-354167 may be used as a method for determining the background. That is, first, an M signal which is a signal obtained by inverting the complementary color of the G signal is extracted from input image data, and a histogram is created by dividing, for example, 256 levels of density into 16 parts. Counting is performed for density sections (class values) that are equal to or lower than the maximum density value (first threshold value) determined to be the background, and a difference between the count values is obtained, and density sections with the difference equal to or greater than the threshold are extracted as the background. Then, a correction amount table corresponding to the extracted density division value is selected, and background removal processing is performed. Instead of the G signal, a luminance signal (255-Y, where Y is Yj = 0.30Rj + 0.59Gi + 0.11Bj (Rj, Gj, Bj: color components of each pixel)) may be used.

  In this embodiment, the background determination is performed by the background determination unit 555, but the CPU 551 may be configured. FIG. 26 is a block diagram showing a modified example of the input tone correction unit 55.

In the above, an example in which the auto color selection process, the document type determination process, and the background determination process are performed individually has been described. However, these processes may be appropriately combined. For example, the auto color selection process and the document type determination process may be performed in parallel, and the color and monochrome document determination result and the document type determination result may be combined and output. Further, the background determination process may be performed after the auto color selection process and the document type determination process. At this time, based on the determination result of the document type, for example, when a character document is included (a character document, a character-printed photo document, a character photographic paper photo document, etc.), the background determination process is performed and the character document is not included. In some cases (printed photo original, photographic paper photo original, etc.), the background determination process may not be performed. This is because a text document usually includes a background, but a photo document or the like that does not include characters contains almost no background.
The processing order of the auto color selection process, the document type determination process, and the background determination process may be switched, or a part or all of the processes may be performed by the CPU.

Embodiment 6 FIG.
In this embodiment, an application example to an image reading apparatus will be described. FIG. 27 is a block diagram showing an internal configuration of the image reading apparatus according to the present embodiment. The image reading device 9 according to the present embodiment includes an image reading unit 91 and an image processing unit 92. The image reading unit 91 includes a scanning unit, an imaging lens, a CCD line sensor, a feeding timing sensor, and the like for optically reading an image of a document.

  The image processing unit 92 includes an AD conversion unit 921, a shading correction unit 922, a document type determination unit 923, and an input tone correction unit 924. The AD conversion unit 921 converts the analog signal read by the image reading unit 91 into a digital signal. The shading correction unit 922 performs shading correction for removing various distortions generated in the illumination system, the imaging system, and the imaging system of the image reading unit 91.

  The document type determination unit 923 treats an RGB signal (RGB reflectance signal) from which various distortions have been removed by the shading correction unit 922 as an image processing system employed in a color image processing apparatus such as a density signal. Converts to an easy signal and determines the document type such as whether the input document image is a text document, a printed photo document, a photographic paper photo, or a combined character / print photo document It is.

  The input tone correction unit 924 adjusts the color balance and simultaneously performs image quality adjustment processing such as background detection, background density removal, and contrast.

  The RGB signal and the document type determination signal subjected to image processing by the image processing unit 92 are input to a computer or a printer and processed according to the document type.

  Although an example in which the document type determination unit 923 is provided is shown above, an ACS determination processing unit as described in the first embodiment may be provided instead of the document type determination unit. Alternatively, the ACS determination process may be incorporated in the document type determination unit 923, and the background determination may be performed by the input tone correction unit 924, and the result may be output together. Further, the image reading apparatus may include a region separation processing unit.

Embodiment 7 FIG.
In the first and second embodiments, each process is realized by hardware. However, the present invention may be realized by software processing.

  FIG. 28 is a block diagram illustrating the internal configuration of an image processing apparatus in which the computer program of the present invention is installed. In the figure, reference numeral 100 denotes an image processing apparatus according to the present embodiment, specifically a personal computer, a workstation, or the like. The image processing apparatus 100 includes a CPU 101, and hardware such as a ROM 103, a RAM 104, a hard disk 105, an external storage unit 106, an input unit 107, a display unit 108, and a communication port 109 is connected to the CPU 101 via a bus 102. Yes. The CPU 101 controls the above-described hardware units according to a control program stored in advance in the ROM 103.

  The RAM 104 is a volatile memory that temporarily stores various data generated during the execution of the above-described control program or the program code (execution format program, intermediate code program, source program) of the computer program according to the present invention. . The hard disk 105 is a storage means having a magnetic recording medium, and stores the program code of the computer program of the present invention. The external storage unit 106 includes a reading device for reading the program code from the recording medium M on which the program code of the computer program of the present invention is recorded. As the recording medium M, an FD (Flexible Disk), a CD-ROM, or the like can be used. The program code read by the external storage unit 106 is stored in the hard disk 105. The CPU 101 loads the program code according to the present invention stored in the hard disk 105 onto the RAM 104 and executes it, thereby causing the entire apparatus to function as an apparatus that realizes image processing as described in the first to fifth embodiments. .

  The input unit 107 functions as an interface for acquiring image data from the outside. For example, a color scanner device or the like is connected to the input unit 107. The display unit 108 functions as an interface for displaying image data to be processed, image data during image processing, image data after image processing, and the like. The display unit 108 may be configured to display image data by connecting an external display device such as a liquid crystal display device, or the display unit 108 may include a display device and display image data. The communication port 109 is an interface for connecting the printer 150 to the outside. When printing image data that has undergone image processing by the printer 150, the image processing apparatus 100 generates print data that can be decoded by the printer 150 based on the image data, and transmits the generated print data to the printer 150. .

  In the present embodiment, the CPU 101 performs various calculations. However, a dedicated chip for performing calculations related to image processing may be separately provided and calculations may be performed according to instructions from the CPU 101.

  As the recording medium M for recording the computer program code according to the present invention, in addition to the above-mentioned FD and CD-ROM, optical recording medium such as MO, MD, DVD, magnetic recording medium such as hard disk, IC card, memory card Further, it is also possible to use a semiconductor memory such as a card-type recording medium such as an optical card, a mask ROM, an EPROM (Erasable Programmable Read Only Memory), an EEPROM (Electrically Erasable Programmable Read Only Memory), a flash ROM, or the like. Further, since the system configuration is such that a communication network including the Internet can be connected, the computer program code according to the present invention may be downloaded from the communication network.

  In addition, the computer program of the present invention may be provided as a single application program or utility program, or may be incorporated into another application program or utility program and provided as a partial function of the program. May be. For example, as one form, a form provided by being incorporated in a printer driver is conceivable. The present invention can also be realized in the form of a computer data signal embedded in a carrier wave in which the program code is embodied by electronic transmission.

It is a block diagram explaining the internal structure of an image processing system provided with the image processing apparatus which concerns on this invention. It is a schematic diagram which shows the structure of an image input device. It is a schematic diagram showing the signal output from a feeding timing sensor. It is a block diagram which shows the internal structure of an ACS determination process part. It is explanatory drawing explaining an effective image area | region. It is a flowchart explaining the procedure of the process which an ACS determination process part performs. It is a flowchart explaining the procedure of the process which an ACS determination process part performs. It is a block diagram which shows the modification of an ACS determination process part. It is a schematic diagram which shows the example of a setting of an effective image area | region. It is a schematic diagram which shows the example of a setting of an effective image area | region. It is a schematic diagram which shows the example of a division | segmentation of a column. It is a schematic diagram which shows the example of a setting of an effective image area | region. It is a schematic diagram which shows the example of a setting of an effective image area | region. It is a schematic diagram which shows the example of a setting of an effective image area | region. It is a schematic diagram which shows the example of storage of the color pixel count number to memory. 6 is a flowchart illustrating a processing procedure when reading a document. It is a flowchart explaining the process sequence at the time of reprinting. It is a schematic diagram which shows the example of storage of the color pixel count number to memory. It is a block diagram explaining the internal structure of an image processing system provided with the image processing apparatus which concerns on this Embodiment. 3 is a block diagram showing an internal configuration of a document type determination unit. FIG. It is a block diagram which shows the detail of a feature-value calculation part and a discrimination | determination result total part. 6 is a flowchart illustrating a procedure of processing executed by a document type determination unit. FIG. 10 is a block diagram illustrating a modified example of a document type determination unit. FIG. 2 is a block diagram showing an internal configuration of an input tone correction unit in the image processing apparatus shown in FIG. 1. It is a flowchart explaining the procedure of the process which an input gradation correction | amendment part performs. It is a block diagram which shows the modification of an input gradation correction | amendment part. 1 is a block diagram illustrating an internal configuration of an image reading apparatus according to an embodiment. It is a block diagram explaining the internal structure of the image processing apparatus in which the computer program of this invention was installed. It is explanatory drawing explaining the example from which a determination result differs depending on an effective image area | region. It is explanatory drawing explaining the example from which a determination result differs depending on an effective image area | region. FIG. 6 is an explanatory diagram for explaining processing when a document is read line by line by an automatic document feeder.

Explanation of symbols

53 ACS Determination Processing Unit 54 Document Type Determination Unit 55 Input Tone Correction Unit 531 541 551 CPU
532, 542, 552 Memory 533 Color pixel determination unit 534 Color pixel count unit 535 Color document determination unit 543 Feature amount calculation unit 544 Discrimination result totaling unit 545 Document determination unit 553 Histogram processing unit 554 Class value totaling unit 555 Background determination unit

Claims (19)

In an image processing method for determining an attribute of an image and performing processing according to the determination result,
The image to be discriminated is sequentially read for each line composed of a plurality of pixels, the feature amount representing the feature of the pixel constituting the read line is calculated, the attribute of the pixel is discriminated based on the calculated feature amount, and the attribute Count the pixels that have been determined, set the area to be processed for the image, and calculate the difference in the number of pixels for which the attribute has been determined from the lines immediately before and after the set area. And determining an attribute of the region based on the calculated difference, and performing processing according to the determination result on the image in the region. In an image processing method for determining an attribute of an image and performing processing according to the determination result,
The image to be discriminated is sequentially read for each line composed of a plurality of pixels, the feature amount representing the feature of the pixel constituting the read line is calculated, the attribute of the pixel is discriminated based on the calculated feature amount, and the attribute The discriminated pixels are counted for each column divided in the main scanning direction, the area to be processed is set for the image, and the attributes calculated from the line immediately before and the line at the rear end of the set area are set. The difference in the number of pixels determined is calculated for each column included in the set area, the attribute of the area is determined based on the calculated sum of the differences for each column, and the process according to the determination result is performed in the area An image processing method characterized by being applied to an image in the image. In an image processing method for determining an attribute of an image and performing processing according to the determination result,
The image to be discriminated is sequentially read for each line composed of a plurality of pixels, the feature amount representing the feature of the pixel constituting the read line is calculated, the attribute of the pixel is discriminated based on the calculated feature amount, and the attribute The determined pixels are counted for each of a plurality of effective image areas set in advance in the main scanning direction, an area to be processed for the image is set, and an area set for the count result corresponding to the set area The difference between the number of pixels for which the attribute has been determined from each of the immediately preceding line and the rearmost line is calculated, the attribute of the region is determined based on the total of the calculated differences, and processing according to the determination result Is applied to the image in the region. In an image processing apparatus that determines an attribute of an image and performs processing according to the determination result,
Means for sequentially reading an image to be discriminated for each line composed of a plurality of pixels; means for calculating a feature amount representing a feature of a pixel constituting the read line; and determining a pixel attribute based on the calculated feature amount; A means for counting the pixels for which the attribute has been determined, a means for setting a region to be processed for the image, and a determination of the attribute calculated from each of a line immediately before and a line at the rear end of the set region. Means for calculating the difference in the number of pixels made, means for determining the characteristics of the region based on the calculated difference, and means for performing processing on the image in the region according to the determination result by the means An image processing apparatus comprising: In an image processing apparatus that determines an attribute of an image and performs processing according to the determination result,
Means for sequentially reading an image to be discriminated for each line composed of a plurality of pixels; means for calculating a feature amount representing a feature of a pixel constituting the read line; and determining a pixel attribute based on the calculated feature amount; Means for counting the pixels for which the attribute has been discriminated for each column divided in the main scanning direction, means for setting an area to be processed for the image, lines immediately before and after the set area, Means for calculating the difference in the number of pixels for which the attribute is calculated from each of the lines for each column included in the set area, and the characteristics of the set area based on the calculated sum of the differences for each column. An image processing apparatus comprising: means for discriminating; and means for applying processing according to a discrimination result by the means to the image in the set area.   Means for discriminating features for a plurality of areas, means for storing discrimination results discriminated for the plurality of areas, and means for applying processing according to the discrimination results to images in each area The image processing apparatus according to claim 5, further comprising: In an image processing apparatus that determines an attribute of an image and performs processing according to the determination result,
Means for sequentially reading an image to be discriminated for each line composed of a plurality of pixels; means for calculating a feature amount representing a feature of a pixel constituting the read line; and determining a pixel attribute based on the calculated feature amount; A means for counting the pixels for which the attribute has been determined for each of a plurality of effective image areas preset in the main scanning direction, a means for setting an area to be processed for the image, and a corresponding area Means for calculating a difference in the number of pixels in which the attribute is calculated from each of the immediately preceding line and the trailing end line of the area set for the counting result, and the set area based on the total sum of the calculated differences An image processing apparatus comprising: means for discriminating a feature of the image; and means for performing processing according to a discrimination result by the means on the image in the area.   Means for discriminating characteristics for a plurality of effective image areas, means for storing the discrimination results discriminated for the plurality of effective image areas, respectively, and which discrimination result is used among the stored discrimination results The image processing apparatus according to claim 7, further comprising: a determining unit; and a unit that performs processing on the image in the region according to the determined determination result.   The image processing apparatus according to claim 4, wherein the attribute of the pixel is chromatic or achromatic of the pixel.   Means for comparing the difference between the number of pixels determined to be chromatic and a predetermined value, and when the difference between the number of pixels determined to be chromatic is larger than the predetermined value, the image is a chromatic image; The image processing apparatus according to claim 9, wherein if the difference is smaller than the predetermined value, the image is determined to be an achromatic image.   The attribute of the pixel is a region separation result indicating whether the pixel belongs to a plurality of regions including a character region or a halftone dot region. Image processing apparatus.   Means for comparing the difference between the number of pixels for each region to which the pixel belongs and a predetermined value provided for each region, wherein the difference in the number of pixels for each region differs from the predetermined value provided for each region; 12. The image processing apparatus according to claim 11, wherein the document type is determined based on the comparison.   The image processing apparatus according to claim 4, wherein the attribute of the pixel is a determination result of whether or not the pixel is a background region.   14. The image processing according to claim 13, further comprising means for comparing a difference between a count value of a class value to which the pixel belongs and a predetermined value, and determining a background based on a comparison result. apparatus. In an image processing apparatus that determines an attribute of an image and performs processing according to the determination result,
Means for sequentially reading the image to be discriminated for each line composed of a plurality of pixels, and calculating a plurality of feature amounts representing the features of the pixels constituting the read line, and calculating a plurality of pixel values based on the calculated plurality of feature amounts Means for determining the attribute, means for counting the pixels for which the attribute has been determined, means for setting an area to be processed for the image, and a line immediately before and a line at the rear end of the set area. Means for calculating the calculated difference in the number of pixels for which each attribute has been determined; means for determining a plurality of features of the region based on the calculated difference; and processing according to the determination result by the means An image processing apparatus comprising: means for applying to an image in a region.   16. An image forming apparatus comprising: the image processing apparatus according to claim 4; and means for forming an image subjected to image processing by the image processing apparatus on a sheet. .   The image processing apparatus according to any one of claims 4 to 15, further comprising: means for reading an image from a document; and determining an attribute of the read image and performing processing according to the determination result. An image reading apparatus. In a computer program that causes a computer to determine the attribute of an image and perform processing according to the determination result,
A step of causing a computer to calculate a feature amount representing a feature of a pixel constituting the line from a line composed of a plurality of pixels, causing the computer to determine a pixel attribute based on the calculated feature amount, and determining the attribute A step of counting the number of pixels made; a step of causing a computer to set an area to be processed for the image; and an attribute calculated from each of a line immediately before and a line at the rear end of the set area. A step of calculating a difference in the number of pixels determined, and a step of causing a computer to determine the attribute of the region based on the calculated difference and performing a process according to the determination result on the image in the region A computer program characterized by comprising: In a computer-readable recording medium in which a computer program for determining the attribute of an image and performing processing according to the determination result is recorded,
A step of causing a computer to calculate a feature amount representing a feature of a pixel constituting the line from a line composed of a plurality of pixels, causing the computer to determine a pixel attribute based on the calculated feature amount, and determining the attribute A step of counting the number of pixels made; a step of causing a computer to set an area to be processed for the image; and an attribute calculated from each of a line immediately before and a line at the rear end of the set area. A step of calculating a difference in the number of pixels determined, and a step of causing a computer to determine the attribute of the region based on the calculated difference and performing a process according to the determination result on the image in the region A computer-readable recording medium in which a computer program including:

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