JP6692212B2 - Image processing apparatus, image forming apparatus including the same, image processing method, image program, and recording medium - Google Patents

Description

  The present invention relates to an image processing apparatus, an image forming apparatus including the same, an image processing method, an image processing program, and a recording medium. In particular, the present invention relates to an image processing apparatus for determining and recognizing a shadow of a paper binder, an image forming apparatus including the image processing apparatus, an image processing method, an image processing program, and a recording medium.

  Conventionally, when an image is read by an image processing apparatus and, for example, a shadow due to a scanner light is generated, there has been an invention that corrects the area of the shadow portion using the attribute of the pixel forming the shadow.

  For example, in Patent Document 1, in order to identify whether the black area detected by the black area detecting unit is a black frame around the original or a shadow formed in a portion where the original and the transparent original stand are separated from each other, An invention using a change in the brightness value in the width direction of a black region is disclosed.

  The specific method is as follows. That is, the same processing is performed from the right end of the image data to the left, searching for a region equal to or greater than the preset brightness value threshold value, and from the lower end of the image data to the upper part. Next, with respect to the detected black area, an average luminance value is obtained for each line, and a differential value that is an average luminance value between adjacent lines is obtained. If the differential value is close to zero over the entire black area, it is determined to be a black frame, and if the differential value does not continue to take a value close to zero over the black area, it is determined to be the shadow of the binding portion.

JP, 2010-62989, A JP, 2002-232708, A

  However, in the shadow of the image read by the image processing apparatus, there is not only a shadow generated simply by separating the original from the transparent original table, but also a “paper-turning” shadow due to paper binding such as a stapler. In this respect, Patent Document 1 does not describe detecting the shadow of the paper binder. Further, it does not describe that the top-bottom direction of the document is aligned based on the position of the shadow of the paper binder, or that the shadow of the paper binder is automatically erased.

  Therefore, it is an object of the present invention to detect the shadow of “paper turning” due to paper binding such as stapler in an image processing apparatus. Further, it is an object of the present invention to align the top and bottom directions of a document on the basis of the position of the shadow of the paper binder and automatically erase the shadow.

  According to a first aspect of the present invention, a pixel for determining whether each of a plurality of pixels forming the area is a solid pixel or an edge pixel with respect to the four corner areas of an input image obtained by reading a document. A determination unit, a binding device shadow candidate detection unit that detects binding device shadow candidates from the solid pixel group that is determined to be a solid pixel by the pixel determination unit, and the number of pixels of pixels that are determined to be edge pixels by the pixel determination unit. An area including the edge counting unit to calculate and the binding device shadow candidate detected by the binding device shadow candidate detection unit, and the area in which the number of edge pixels calculated by the edge counting unit is within a predetermined range is the four corners. And a binding tool shadow determination unit that determines that the binding tool shadow candidate is an actual binding tool shadow, the image processing apparatus is provided.

  According to a second aspect of the present invention, there is provided an image forming apparatus including the image processing device.

  According to a third aspect of the present invention, for each of the four corner regions of the input image obtained by reading the original, it is determined whether each of the plurality of pixels forming the region is a solid pixel or an edge pixel, The binding tool shadow candidate is detected from the solid pixel group determined to be the solid pixel, the number of pixels of the pixel determined to be the edge pixel is calculated, the binding tool shadow candidate is included, and the calculated number of the edge pixel is When the area within the range between the first threshold value and the second threshold value is one of the four corner areas, it is determined that the binding tool shadow candidate is an actual binding tool shadow. An image processing method is provided.

  According to a fourth aspect of the present invention, there is provided an image processing program for operating the image processing device, the image processing program causing a computer to function as each unit included in the image processing device.

  According to a fifth aspect of the present invention, there is provided an image forming program for operating the image forming apparatus, the image forming program causing a computer to function as each unit included in the image forming apparatus.

  According to a sixth aspect of the present invention, there is provided a recording medium having the image processing program stored therein in a computer-readable manner.

  According to a seventh aspect of the present invention, there is provided a recording medium having the image forming program stored therein in a computer-readable manner.

  According to the present invention, the image processing apparatus can detect the shadow of “paper turning” due to binding of paper such as stapler.

It is a figure which shows the structural example of the principal part of the image processing apparatus which concerns on the 1st Embodiment of this invention. It is a figure which shows the structural example of a binding tool shadow detection part in the image processing apparatus which concerns on the 1st Embodiment of this invention, and the cooperation state of a binding tool shadow detection part and a binding tool shadow determination part. It is a figure which shows the structural example of a binding tool shadow detection part in the image processing apparatus which concerns on the 1st Embodiment of this invention, and the cooperation state of a binding tool shadow detection part and a binding tool shadow determination part. It is a figure which shows the structural example of the character recognition processing part in the image processing apparatus which concerns on the 1st Embodiment of this invention. It is a figure which shows the character recognition processing method by the character recognition processing part in the image processing apparatus which concerns on the 1st Embodiment of this invention. It is a figure which shows the flow of the binding tool shadow determination method by the image processing apparatus which concerns on the 1st Embodiment of this invention. It is a figure which shows the flow of the binding tool shadow determination method by the image processing apparatus which concerns on the 1st Embodiment of this invention. It is a figure which shows the binding tool shadow determination pattern by the image processing apparatus which concerns on the 1st Embodiment of this invention. It is a figure which shows the binding tool shadow determination pattern by the image processing apparatus which concerns on the 1st Embodiment of this invention. It is a figure which shows the binding tool shadow determination pattern by the image processing apparatus which concerns on the 1st Embodiment of this invention. It is a figure which shows the binding tool shadow determination pattern by the image processing apparatus which concerns on the 1st Embodiment of this invention. FIG. 6 is an explanatory diagram of a density histogram of solid pixels used by the image processing apparatus according to the first embodiment of the present invention. FIG. 6 is an explanatory diagram of a density histogram of solid pixels used by the image processing apparatus according to the first embodiment of the present invention. It is a figure which shows the structural example of the binding tool shadow exclusive processing part in the image processing apparatus which concerns on the 1st Embodiment of this invention. It is a figure which shows the structural example of the binding tool shadow exclusive processing part in the image processing apparatus which concerns on the 1st Embodiment of this invention. It is a figure which shows the structural example of the binding tool shadow exclusive processing part in the image processing apparatus which concerns on the 1st Embodiment of this invention. It is a figure which shows the up-and-down direction determination pattern by the image processing apparatus which concerns on the 1st Embodiment of this invention. It is a figure which shows the up-and-down direction determination pattern by the image processing apparatus which concerns on the 1st Embodiment of this invention. It is a figure which shows the up-and-down direction determination pattern by the image processing apparatus which concerns on the 1st Embodiment of this invention. It is a figure which shows the up-and-down direction determination pattern by the image processing apparatus which concerns on the 1st Embodiment of this invention. It is a figure which shows the example of binding tool shadow processing content by the image processing apparatus which concerns on the 1st Embodiment of this invention. It is a figure which shows the structural example of the image forming apparatus which concerns on the 2nd Embodiment of this invention. It is a figure which shows the structural example of the image forming apparatus which concerns on the 2nd Embodiment of this invention. It is a figure which shows the structural example of the image forming apparatus which concerns on the 2nd Embodiment of this invention. It is a figure which shows the structural example of the image forming apparatus which concerns on the 2nd Embodiment of this invention. FIG. 8 is a diagram showing a correction example by a color correction unit in the image forming apparatus according to the second embodiment of the present invention.

  Hereinafter, the first embodiment of the present invention will be described in detail with reference to FIGS. 1 to 10.

[First Embodiment]
<1.1 Example of Configuration of Image Processing Device>
FIG. 1 shows a configuration example of a main part of an image processing apparatus according to the first embodiment of the present invention. The image processing apparatus 100 includes a binding device shadow detection unit 110, a binding device shadow determination unit 120, and a binding device shadow dedicated processing unit 130. The binding device shadow detection unit 110 detects a binding device shadow candidate area that may be a shadow generated by a paper binding device such as a stapler. The binding tool shadow determination unit 120 determines whether or not the binding tool shadow candidate area is an actual binding tool shadow. When it is determined that the above area is the shadow of the actual binding tool, the binding tool shadow dedicated processing unit 130 performs image processing on the shadow of the actual binding tool or according to the position of the actual binding tool. , Image processing such as top-bottom correction is performed on the image of the document.

<1.2.1 Configuration example and operation of binding tool shadow detection unit and binding tool shadow determination unit>
FIG. 2A is a diagram showing a configuration example of the binding tool shadow detection unit 110 and a relation between the binding tool shadow detection unit 110 and the binding tool shadow determination unit 120. The binding device shadow detection unit 110 includes a pixel determination unit 111, a histogram generation unit 112, a binding device shadow candidate detection unit 119, and an edge counting unit 113. These operations will be described with reference to the flowchart of FIG.

  First, in STEP 11, the pixel determination unit 111 extracts solid pixels and edge pixels existing in the four corner regions in the input image. As the four corner areas, for example, in the case of an A4 size (295 mm × 210 mm) original, a 15 mm × 15 mm square area is defined as the four corner areas. (In the examples of FIGS. 6-1, 6-2, 6-3, and 6-4, the regions are dotted rectangles in each figure.) Solid pixels and edge pixels are extracted from each of these regions. To do.

For the distinction between solid pixels and edge pixels, for example, the method described in Patent Document 2 is used. Specifically, it is as follows.
(11-1) The minimum density value and the maximum density value in the n × m (for example, 7 × 15) block including the target pixel are calculated.
(11-2) The maximum density difference is calculated using the calculated minimum density value and maximum density value.
(11-3) In the above block, the total density busyness (for example, the sum of the values calculated in the main scanning direction and the sub scanning direction) that is the sum of the absolute values of the density differences of adjacent pixels is calculated.
(11-4) The calculated maximum density difference is compared with the maximum density difference threshold, and the calculated total density busyness is compared with the total density busyness threshold. In particular,
When the maximum density difference <maximum density difference threshold and the total density busyness <total density busyness threshold, it is determined that the pixel of interest belongs to a solid pixel (background / photographic paper photograph area). Here, the solid pixel is, for example, a background / photographic paper photograph area.
When the above conditions are not satisfied, it is determined that the pixel of interest belongs to an edge pixel. Here, the edge pixel is, for example, a character / halftone dot area.

  A method other than the above, for example, a method of thresholding the absolute value of the difference between the pixel values of adjacent pixels or a method of using a filter such as a Sobel filter or a Laplacian filter may be used for the edge extraction.

  Next, in STEP 12, the edge counting unit 113 counts the number of pixels determined as edge pixels by the pixel determining unit 111 in each of the four corner areas of the input image. Here, this count value is named "COUNTedge".

Next, in STEP 13, the histogram generation unit 112 creates a density histogram with the number of pixels on the vertical axis and the density on the horizontal axis of the pixel group determined to be solid pixels by the pixel determination unit 111. Here, as the density, for example, the following brightness values are used.
Yi = 0.30Ri + 0.59Gi + 0.11Bi
(Y: luminance signal of each pixel R, G, B: value of each color component of each pixel, subscript i: value given to each pixel (i is an integer of 1 or more))

  Next, in STEP 14, the binding device shadow candidate detection unit 119 recognizes the lightest density area as the original background for each of the four histograms corresponding to the four corners of the input image, and the lightest density next to the original background density area. Recognize the area as the density area of the binding tool shadow candidate. An example thereof is shown in FIGS. 7-1 and 7-2. In FIG. 7A, a density histogram is generated for the solid pixels in the upper left dotted rectangle in the document. Of the pixels within the dotted-line rectangle in FIG. 7A, the solid pixels in the area shown in white are the peaks on the right side of the histogram in FIG. On the other hand, among the pixels within the dotted-line rectangle in FIG. 7A, the solid pixels in the shaded area are the peaks on the left side with the next lightest density in the histogram of FIG. 7B. The binding tool shadow candidate detection unit 119 sets the mountain on the left side as a binding tool shadow candidate. The binding device shadow candidate detection unit 119 performs this density histogram analysis not only on the upper left region of the document in FIG. 7A but also on the other three regions, that is, the upper right, lower left, and lower right regions.

Next, in STEP 15, the binding tool shadow determination unit 120 determines whether or not the following two conditions are satisfied for each of the four corner regions.
(15-1) In the density histogram, is there a density range that is darker than the original background (the above-mentioned light density mountain next to the original background)?
(15-2) Whether the number of edge pixels (COUNTedge) is within a predetermined range, that is, within a range that exceeds the first threshold and is less than the second threshold.
When the area in which both (15-1) and (15-2) are satisfied is only one of the four corner areas (YES in STEP 15), in STEP 16, the binding device shadow determination unit 120 It is determined that the binding tool shadow exists in one area. On the other hand, if there is no area in which both (15-1) and (15-2) are satisfied, or if there are two or more areas (NO in STEP 15), in STEP 17, the binding device shadow determination unit 120 It is determined that there is no binding tool shadow in any of the four areas.

<1.2.2 Configuration example and operation of binding tool shadow detection section and binding tool shadow determination section when binding tool shadow detection section further includes a character recognition processing section>
In the above description, the mode in which the binding device shadow detection unit 110 includes the pixel determination unit 111, the histogram generation unit 112, the edge counting unit 113, and the binding device shadow candidate detection unit 119 has been described above with reference to FIG. As shown in FIG. 2B, the binding device shadow detection unit 110 may further include a character recognition processing unit 114. A configuration example and operation of the character recognition processing unit 114 will be described in detail below with reference to FIGS.

  As shown in FIG. 3, the character recognition processing unit 114 includes a signal conversion unit 115, a binarization processing unit 116, a layout analysis unit 117, and a character recognition unit 118.

The signal conversion unit 115 converts the RGB color image data into luminance data using the following formula.
Yi = 0.30Ri + 0.59Gi + 0.11Bi
(Y: luminance signal of each pixel R, G, B: value of each color component of each pixel, subscript i: value given to each pixel (i is an integer of 1 or more))
Instead of the above equation, RGB signals may be converted into CIE1976 L * a * b * signals (CIE: Commission International de l'Eclairage, L *: lightness, a *, b *: chromaticity), or G signals. May be used.

  The binarization processing unit 116 binarizes the above luminance data. When the luminance signal is 8 bits, the threshold value is set to 128, for example. Alternatively, the average value of the densities (pixel values) of a block composed of a plurality of pixels (for example, 5 × 5) may be used as the threshold value.

Next, the layout analysis unit 117 performs a layout analysis of the luminance data to extract a character string, and distinguishes the character string into characters on a character-by-character basis. Specifically, as shown in FIG. 4, a circumscribing rectangle is obtained for each character, and the character strings are distinguished for each character. The circumscribed rectangle is obtained as follows, for example.
(1) An arbitrary line is set as the first line of interest, and black pixels in the line of interest are labeled.
(2) The line of interest is shifted to the line immediately below, and a label different from the black pixel in the above line is set for the black pixel in the line below.
(3) The connection state of the black pixels of the line of interest and the upper line is determined. If they are connected, it is determined that the pixels are connected, and the label of the black pixel in the line of interest is changed to the black of the upper line. Replace with the same label as the pixel.
(4) The above process is repeated to extract characters. A circumscribed rectangle is extracted from the extracted character region based on the pixel positions of the upper end, the lower end, the left end, and the right end. The coordinates of the pixel are obtained by using the position of the left end of the read image data as the origin.

Next, the character recognition unit 118 performs character recognition on the characters distinguished for each character. Specifically, the character to be recognized is converted into a size of a predetermined size (for example, 10 points) (normalization processing is performed). Next, the character recognition is performed by superimposing and comparing the normalized character and the pattern for each character registered as dictionary data.
The configuration example and the operation of the character recognition processing unit 114 are as described above.

  As described above, when the binding device shadow detection unit 110 includes the character recognition processing unit 114, the binding device shadow detection unit 110 and the binding device shadow determination unit 120 perform the operation illustrated in the flowchart of FIG. .. Compared to the flowchart of FIG. 5A, in the flowchart of FIG. 5-2, the character recognition processing unit 114 recognizes the characters in the four corner regions of the input image, counts the number of recognized characters (COUNTTocr), and then the count value. Is used for determining the presence or absence of the binding tool shadow. Although partially overlapping with the description according to FIG. 5A, the flowchart described in FIG. 5-2 is specifically as follows.

  First, in STEP 21, the pixel determination unit 111 extracts solid pixels and edge pixels existing in the four corner regions in the input image.

  Next, in STEP 22, the edge counting unit 113 counts the number of pixels determined by the pixel determining unit 111 to be edge pixels in each of the four corner regions of the document. This count value is referred to as "COUNTedge".

  Next, in STEP23, the histogram generation unit 112 creates a density histogram with the number of pixels on the vertical axis and the density on the horizontal axis for the pixel group determined to be a solid pixel by the pixel determination unit 111.

  Next, in STEP 24, the binding tool shadow candidate detection unit 119 recognizes the lightest density area as the original background for each of the four histograms corresponding to the four corners, and binds the lightest density area next to the original background density area. Recognize that it is the density range of a candidate for a shadow.

  Next, in STEP 25, the character recognition processing unit 114 recognizes a character in each of the four corner areas of the document.

  Next, in STEP 26, the character recognition processing unit 114 counts the number of recognized characters in each of the four corner areas of the document. This is named "COUNTTocr" here.

Next, in STEP 27, the binding device shadow determination unit 120 determines whether or not the following three conditions are satisfied for each of the four corner regions.
(27-1) In the density histogram, is there a density range that is darker than the original background (the above-mentioned light density mountain next to the original background)?
(27-2) Whether the number of edge pixels (COUNTedge) is within a predetermined range, that is, within a range that exceeds the first threshold value and is less than the second threshold value.
(27-3) Is COUNTTocr above 0?
When the area where all of (27-1) to (27-3) are satisfied is only one of the four corner areas (YES in STEP 27), in STEP 28, the binding device shadow determination unit 120 It is determined that the binding tool shadow exists in the one area. On the other hand, when there is no area in which all of the above (27-1) to (27-3) are satisfied or there are two or more areas (NO in STEP 27), in STEP 29, the binding device shadow determination unit 120 , It is determined that there is no binding tool shadow in any of the four areas.

<1.3 Configuration example and operation of binding tool shadow dedicated processing unit>
As described above, when the binding device shadow determination unit 120 determines that the binding device shadow exists in only one of the current four corner areas, the binding device shadow dedicated processing unit 130 illustrated in FIG. The image processing is performed only for the original document that is determined to exist.

  8A to 8C show first to third examples of the configuration of the binding tool shadow dedicated processing unit 130.

  In the first example illustrated in FIG. 8A, the binding tool shadow dedicated processing unit 130 includes an upside down determination unit 131 and an upside down correction unit 132.

  The upside-down determination unit 131 indicates that the document is facing upward when the area determined to have the binding tool shadow exists in the upper left as in FIG. 9A or in the upper right as in FIG. 9B. To determine. On the other hand, when the area determined to have the binding tool shadow exists in the lower left as in FIG. 9-3 or in the lower right as in FIG. 9-4, the document is determined to be facing downward. To do.

  The upside-down correction unit 132 performs 180 ° rotation processing when the upside-down determination unit 131 determines that the document is facing downward, and performs upside-down correction so that the document faces upward. If it is determined that the document faces up, no processing is performed.

  In the second example illustrated in FIG. 8B, the binding device shadow dedicated processing unit 130 includes a binding device shadow erasing unit 133. As shown in FIG. 10, the binding device shadow erasing unit 133 replaces the entire area in which the binding device shadow is determined to exist with the pixel of the average density value of the density range determined to be the original background in the density histogram. When the original is a color original, not only the entire area determined to have the binding tool shadow is replaced with the pixels of the average density value of the density area determined to be the original background, but also the area determined to be the original background. It may be replaced with a pixel having a similar color tone.

  The third example illustrated in FIG. 8C is an example in which the binding device shadow dedicated processing unit 130 includes all of the above-described upside-down determination unit 131, the upside-down correction unit 132, and the binding device shadow removal unit 133.

<1.4 Modification of First Embodiment>
The edge counting unit 113 counts the number of edge pixels, but in addition to this, the edge pixel coordinate values may be acquired. In this case, when the distribution area of the edge pixels is formed in a linear shape, the binding tool shadow determination is performed on the condition that the angle between the line and the vertical direction of the original image is within a predetermined range. The unit 120 may determine that the binding tool shadow exists in one area.

  Hereinafter, the second embodiment of the present invention will be described in detail with reference to FIGS. 11 to 15.

[Second Embodiment]
<2.1 Printing operation by multifunction device>
FIG. 11 shows an image forming apparatus 500 including an image processing apparatus 570 according to the second embodiment of the present invention (for example, a digital copying machine, a copier function, a printer function, a facsimile transmission function, a scan to e-mail function, etc.). 6A and 6B are diagrams illustrating a configuration example of a multi-function peripheral) and a signal flow during a printing operation.

  The image processing device 570 includes an A / D conversion unit 505, a shading correction unit 510, an input processing unit 515, a document type automatic determination unit 520, a binding tool shadow dedicated processing unit 525, a color correction unit 530, a region separation unit 535, and black generation. A lower color removal unit 540, a spatial filter unit 545, an output tone correction unit 550, and a halftone generation unit 555, which are not shown in FIG. 11, but are further formatted as shown in FIG. 560 is provided.

  The image forming apparatus 500 further includes an image input device 10, an image output device 20, a transmission / reception device 30, a storage unit 40, and a control unit 50, in addition to the above-described image processing device 570.

  The image input device 10 is composed of a CCD (Charge Coupled Device) line sensor, and converts the light reflected from the document into R, G, B (R: red, G: green, B: blue) color-separated electrical signals. To do. A color image signal (RGB analog signal) input by the CCD line sensor is converted into a digital signal by an A / D (analog / digital) conversion unit 505, and a shading correction unit 510 connects an illumination system of the image input device and a connection. Various distortions caused in the image system and the image pickup system are removed. After that, the input processing unit 515 performs a process of correcting γ (input gradation) on each of the RGB signals.

  The data output from the input processing unit 515 is delivered to the storage unit 40. This image data may be managed as filing data. In this case, the image data is compressed into a JPEG code based on the JPEG compression algorithm and stored. When a copy output operation or a print output operation is instructed, the JPEG code is extracted from the hard disk, passed to a JPEG decompression unit (not shown), and subjected to decoding processing to be converted into RGB data.

  The document type automatic determination unit 520 determines the type of input image data. The binding tool shadow detection unit and the binding tool shadow determination unit according to the first embodiment are incorporated in the document type automatic determination unit 520. Here, the types of originals to be determined include a text original, a photo (continuous tone photo) original, a print photo original, a text print photo original in which characters and print pictures are mixed, and the like. It is determined whether or not there is a shadow due to the paper binding tool.

For the automatic document type determination, for example, the method described in Patent Document 2 can be used. Specifically, it is as follows.
(1) The minimum density value and the maximum density value in the n × m (eg, 7 × 15) block including the pixel of interest are calculated.
(2) The maximum density difference is calculated using the calculated minimum density value and maximum density value.
(3) The total density busyness (eg, the sum of the values calculated in the main scanning direction and the sub scanning direction), which is the sum of the absolute values of the density differences of adjacent pixels, is calculated.
(4) The calculated maximum density difference is compared with the maximum density difference threshold, and the calculated total density busyness is compared with the total density busyness threshold.
When the maximum density difference <maximum density difference threshold and the total density busyness <total density busyness threshold, it is determined that the pixel of interest belongs to the background / photographic paper photograph area.
When the above condition is not satisfied, it is determined that the pixel of interest belongs to the character / dot area.
(5) Pixels determined to belong to the background / photographic paper photograph area When the target pixel satisfies the maximum density difference <background / photographic paper photograph determination threshold value, it is determined to be a background pixel, and the above conditions are not satisfied. , It is determined that the pixel is a photographic paper photograph (continuous tone area) pixel.
(6) Pixel determined to belong to character / halftone dot area When the pixel of interest satisfies the condition of sum total density complexity <maximum density difference multiplied by character / halftone dot judgment threshold value, it is a character pixel If the above conditions are not satisfied, it is determined that the pixel is a halftone dot pixel.
(7) Count the number of pixels classified into the background area, the photographic paper photograph area, the character area, and the halftone dot area, and use the respective count values as the predetermined base area, photographic paper photograph area, and halftone dot. The type of the entire document is determined by comparing with the thresholds for the area and the character area. For example, assuming that the detection accuracy is higher in the order of characters, halftone dots and photographic paper photographs, when the ratio of the character area is 30% or more of the total number of pixels, the ratio of the character original and the halftone dot area is 20% of the total number of pixels. In the above cases, it is determined that the halftone dot original (printed photo original) is a photographic paper photo original when the ratio of the photographic paper photo area is 10% or more of the total number of pixels. Further, when the ratio of the character area and the ratio of the halftone area are equal to or more than the respective thresholds, it is determined that the original is a character / halftone original (character printed photograph original).

  The binding tool shadow dedicated processing unit 525 performs processing such as binding tool shadow erasing processing and top-and-bottom correction when it is determined that the document is a document with a paper binding tool shadow.

  In the color correction unit 530, a CMY (C: cyan, M: magenta, Y: yellow) signal that is a complementary color of the RGB signal is generated and processing for increasing color reproducibility is performed, and a black generation / undercolor removal unit 540 is performed. Are converted into CMYK (K: black) four color signals. The spatial filter section 545 performs emphasis processing and smoothing processing on the CMYK signals, and the output tone correction section 550 performs output γ correction processing for outputting to a recording medium such as paper. The halftone generation unit 555 performs gradation reproduction processing for outputting an image.

  On the other hand, in the area separating unit 535, it is determined what kind of area each pixel of the input image data belongs to, such as a black character, a color character, a halftone dot, and a photographic paper photograph (continuous tone area). The area separation signals output from the area separation unit 535 are delivered to the black generation / undercolor removal unit 540, the spatial filter unit 545, and the halftone generation unit 555, respectively, and appropriate processing switching is performed according to various areas.

  The CMYK signals output from the halftone generating unit 555 are delivered to the image output device 20 to form an output image. The image output device 20 is a device that reproduces an image, such as an electrophotographic printer or an inkjet printer.

  FIG. 12 shows an example of the physical configuration of the image forming apparatus 500 in which the present invention is implemented.

The image forming apparatus 500 forms a multicolor image and a single color image on a predetermined sheet (recording sheet) according to image data transmitted from the outside, and includes an apparatus main body 810, an automatic document processing apparatus 820. It is composed by. The apparatus main body 810 includes an exposure unit 701, a developing device 702, a photoconductor drum 703, a cleaner unit 704, a charger 705, an intermediate transfer belt unit 706, a fixing unit 707, a paper feed cassette 781, a paper discharge tray 791 and the like. It is configured.

  An original placing table 792 made of transparent glass on which an original is placed is provided on the upper part of the apparatus main body 810, and an automatic original processing device 820 is attached on the upper side of the original placing table 792. The automatic document processing device 820 automatically conveys a document onto the document table 792. Further, the document processing device 820 is configured to be rotatable in the direction of the arrow M, and the document can be manually placed by opening the document table 792.

  The image data handled in this image forming apparatus corresponds to a color image using each color of black (K), cyan (C), magenta (M), and yellow (Y). Therefore, the developing device 702, the photoconductor drum 703, the charging device 705, and the cleaner unit 704 are provided four by four so as to form four types of latent images corresponding to each color, and are respectively black, cyan, magenta, and yellow. The four image stations are configured by these.

  The charger 705 is a charging means for uniformly charging the surface of the photoconductor drum 703 to a predetermined potential, and in addition to the charger type as shown in FIG. 13, a contact type roller type or brush type charger is also available. Sometimes used.

  The exposure unit 701 corresponds to the image writing apparatus according to the present invention, and is configured as a laser scanning unit (LSU) including a laser emitting unit, a reflection mirror, and the like. The exposure unit 701 is provided with a polygon mirror that scans a laser beam and optical elements such as a lens and a mirror that guide the laser light reflected by the polygon mirror to the photosensitive drum 703. The configuration of the optical scanning device that constitutes the exposure unit 701 will be specifically described later. Further, as the exposure unit 701, a method of using, for example, an EL or LED writing head in which light emitting elements are arranged in an array can also be used.

  The exposure unit 701 has a function of exposing the charged photosensitive drum 703 according to the input image data to form an electrostatic latent image on the surface thereof according to the image data. The developing device 702 visualizes the electrostatic latent image formed on each photoconductor drum 703 with toner of four colors (YMCK). The cleaner unit 704 removes and collects the toner remaining on the surface of the photoconductor drum 703 after development and image transfer.

  The intermediate transfer belt unit 706 disposed above the photoconductor drum 703 includes an intermediate transfer belt 761, an intermediate transfer belt driving roller 762, an intermediate transfer belt driven roller 763, an intermediate transfer roller 764, and an intermediate transfer belt cleaning unit 765. I have it. Four intermediate transfer rollers 764 are provided corresponding to each color for YMCK.

  The intermediate transfer belt driving roller 762, the intermediate transfer belt driven roller 763, and the intermediate transfer roller 764 stretch the intermediate transfer belt 761 to rotate it. Further, each intermediate transfer roller 764 provides a transfer bias for transferring the toner image on the photosensitive drum 703 onto the intermediate transfer belt 761.

  The intermediate transfer belt 761 is provided so as to be in contact with each photoconductor drum 703, and the toner images of the respective colors formed on the photoconductor drum 703 are sequentially superposed and transferred onto the intermediate transfer belt 761. , And has a function of forming a color toner image (multicolor toner image) on the intermediate transfer belt 761. The intermediate transfer belt 761 is formed in an endless shape using a film having a thickness of about 100 μm to 150 μm, for example.

  The transfer of the toner image from the photosensitive drum 703 to the intermediate transfer belt 761 is performed by the intermediate transfer roller 764 which is in contact with the back side of the intermediate transfer belt 761. A high-voltage transfer bias (a high voltage having a polarity (+) opposite to the charging polarity (−) of the toner) is applied to the intermediate transfer roller 764 in order to transfer the toner image. The intermediate transfer roller 764 is a roller whose base is a metal (for example, stainless steel) shaft having a diameter of 8 to 10 mm and whose surface is covered with a conductive elastic material (for example, EPDM or urethane foam). With this conductive elastic material, a high voltage can be uniformly applied to the intermediate transfer belt 761. In this embodiment, a roller shape is used as the transfer electrode, but a brush or the like can be used instead.

  As described above, the electrostatic images visualized in accordance with the respective hues on the respective photosensitive drums 703 are laminated on the intermediate transfer belt 761. In this way, the stacked image information is transferred onto the paper by the transfer roller 710 arranged at the contact position between the paper and the intermediate transfer belt 761 described later by the rotation of the intermediate transfer belt 761.

  At this time, the intermediate transfer belt 761 and the transfer roller 710 are pressed against each other at a predetermined nip, and a voltage for transferring the toner to the sheet is applied to the transfer roller 710 (a polarity opposite to the charging polarity (-) of the toner). (+) High voltage). Further, in order to constantly obtain the above nip, the transfer roller 710 uses one of the transfer roller 710 and the intermediate transfer belt drive roller 762 as a hard material (metal or the like) and the other as a soft material (elasticity or the like). A rubber roller, a foaming resin roller or the like) is used.

  Further, as described above, the toner attached to the intermediate transfer belt 761 by contacting the photosensitive drum 703, or the toner remaining on the intermediate transfer belt 761 without being transferred onto the sheet by the transfer roller 710, is generated in the next step. In this case, the intermediate transfer belt cleaning unit 765 is set to remove and collect the toner in order to cause color mixing of toner. The intermediate transfer belt cleaning unit 765 is provided with, for example, a cleaning blade that comes into contact with the intermediate transfer belt 761 as a cleaning member. The intermediate transfer belt 761 that comes into contact with the cleaning blade is supported by the intermediate transfer belt driven roller 763 from the back side. ing.

  The paper feed cassette 781 is a tray for accumulating sheets (recording paper) used for image formation, and is provided below the exposure unit 701 of the apparatus main body 810. A sheet used for image formation can also be placed in the manual paper feed cassette 782. A paper discharge tray 791 provided above the apparatus main body 810 is a tray for stacking printed sheets face down.

  Further, the apparatus main body 810 is provided with a substantially vertical paper transport path S for sending the sheets of the paper feed cassette 781 and the manual paper feed cassette 782 to the paper discharge tray 791 via the transfer roller 710 and the fixing unit 707. Has been. In the vicinity of the paper transport path S from the paper feed cassette 781 or the manual paper feed cassette 782 to the paper discharge tray 791, pickup rollers 711a and 711b, a plurality of transport rollers 712a to 712d, a registration roller 713, a transfer roller 710, and a fixing unit. 707 etc. are arranged.

  The transport rollers 712a to 712d are small rollers for promoting and assisting the transport of the sheet, and a plurality of them are provided along the sheet transport path S. The pickup roller 711 a is provided near the end of the sheet feeding cassette 781 and picks up the sheets one by one from the sheet feeding cassette 781 and supplies the sheets to the sheet conveying path S. Similarly, the pickup roller 711b is provided near the end of the manual paper feed cassette 782, and picks up the sheets one by one from the manual paper feed cassette 782 and supplies them to the paper transport path S.

  Further, the registration roller 713 temporarily holds the sheet being conveyed on the sheet conveying path S. Then, it has a function of conveying the sheet to the transfer roller 710 at the timing when the front edge of the toner image on the photosensitive drum 703 and the front edge of the sheet are aligned.

  The fixing unit 707 includes a heat roller 771 and a pressure roller 772, and the heat roller 771 and the pressure roller 772 are configured to rotate while sandwiching a sheet. Further, the heat roller 771 is set by the control unit to reach a predetermined fixing temperature based on a signal from a temperature detector (not shown). It has the function of melting, mixing, and pressing the transferred multicolor toner image to heat-fix it to the sheet. Further, an external heating belt 773 for heating the heat roller 771 from the outside is provided.

  Next, the sheet conveying path will be described in detail. As described above, the image forming apparatus 500 is provided with the sheet feeding cassette 781 that stores sheets in advance and the manual sheet feeding cassette 782. Pickup rollers 711a and 711b are arranged to feed the sheets from the sheet feeding cassettes 781 and 782, respectively, and the sheets are guided to the transport path S one by one.

  The sheet conveyed from each of the sheet feeding cassettes 781 and 782 is conveyed to the registration roller 713 by the conveyance roller 712a of the sheet conveyance path S, and the transfer roller is transferred at the timing of aligning the leading end of the sheet with the leading end of the image information on the intermediate transfer belt 761. The sheet is conveyed to 710 and image information is written on the sheet. Thereafter, as the sheet passes through the fixing unit 707, the unfixed toner on the sheet is melted and fixed by heat, and then the sheet is discharged onto the sheet discharge tray 791 through the transport roller 712b arranged.

  The above-mentioned conveyance path is used for the one-sided printing request for the sheet. On the other hand, when the two-sided printing is requested, the trailing edge of the sheet passing through the fixing unit 7 after the one-sided printing is finished as described above. When the sheet is finally gripped by the transport roller 712b, the transport roller 712b rotates in the reverse direction to guide the sheet to the transport rollers 712c and 712d. Then, after the printing is performed on the back surface of the sheet via the registration rollers 713, the sheet is ejected to the sheet ejection tray 791.

  The image output device 20 in the description using FIG. 11 basically corresponds to the device body 810.

<2.2 Image transmission operation by multifunction device>
FIG. 13 is an image forming apparatus 500 including an image processing apparatus 570 according to an embodiment of the present invention (a digital copying machine, a copier function, a printer function, a facsimile transmission function, a scan to e-mail function, and the like). 3 is a diagram showing an example of the configuration of FIG. 1 and a signal flow during an image transmission operation.

  When the image forming apparatus 500 is operated during the transmission processing in the image transmission mode, the image input apparatus 10, the A / D (analog / digital) conversion section 505, the shading correction section 510, the input processing section 515, the automatic document type determination section 520. The operation contents of the binding tool shadow dedicated processing unit 525 and the area separation unit 535 are the same as the operation contents at the time of the printing operation, and thus description thereof will be omitted. The area separation unit 535 outputs the area separation signal to the spatial filter unit 545 and the output gradation correction unit 550.

  In the color correction unit 530, the RGB signals are converted into R′G′B ′ image data (for example, sRGB data) that matches the display characteristics of display devices that are widely used, and the spatial filter unit 545 separates the regions. Spatial filter processing (enhancement processing, smoothing processing) by a digital filter is performed based on the signal. In the output gradation correction unit 550, for example, the gamma curve in FIG. 14B is corrected for the character area, and the gamma curve in FIG. Is corrected using.

  The black generation / undercolor removal unit 540 and the halftone generation unit 555 do not process the input image data, and output the image data as it is to the subsequent block.

  The image data of R′G′B ′ output from the output gradation correction unit 550 is converted into an image file such as a PDF file by the formatting processing unit 560 and attached to an email by a mail processing unit (not shown). E-mail is sent to the other party via the network.

  As described above, when the copy output operation or the print output operation is instructed, the JPEG code is extracted from the hard disk, passed to the JPEG decompression unit (not shown), decoded, and converted into RGB data. .. On the other hand, in the case of the image transmitting operation, the JPEG code is extracted from the hard disk and the data is transmitted to the external connection device or the communication line via the network or the communication line. Note that the filing data management and data transfer operation control are performed by the control unit.

<2.3 Image Reading Operation by Scanner>
FIG. 14 is a diagram showing a configuration example of an image reading device 600 (scanner) including an image processing device 650 according to an embodiment of the present invention, and a signal flow at the time of image reading.

  The image reading device 600 includes an image processing device 650, an image input device 10, a storage unit 40, and a control unit 50. The image processing device 650 includes an A / D conversion unit 605, a shading correction unit 610, and an input processing unit 615. An automatic document type determination unit 620, a binding tool shadow dedicated processing unit 625, a color correction unit 630, and a formatting processing unit 635 are provided. The functions of the respective constituent elements are the same as the corresponding constituent elements in the image forming apparatus 500, and therefore the description thereof will be omitted. The RGB image signal that has undergone the above-described processing in the image processing device 650 is output to a computer, a server, or the like.

  Hereinafter, the third embodiment of the present invention will be described in detail.

[Third Embodiment]
<3 Recording media and programs>
In the present invention, the image processing method according to the first embodiment may be recorded on a computer-readable recording medium that records a program to be executed by a computer.
As a result, it is possible to freely provide a recording medium on which the program code (execution format program, intermediate code program, source program) for performing the above processing is recorded.

  In the present embodiment, the recording medium may be a program medium such as a memory (not shown) such as a ROM itself because the processing is performed by a microcomputer. Alternatively, a program reading device may be provided as an external storage device, and the program medium may be readable by inserting a recording medium therein.

  In any case, the stored program may be configured to be accessed and executed by a microprocessor, or in any case, the program code is read and the read program code is read by a microcomputer. The program may be downloaded to a program storage area (not shown) and the program may be executed. It is assumed that this download program is stored in the main body device in advance.

  Here, the program medium is a recording medium that can be separated from the main body, and is a tape system such as a magnetic tape or a cassette tape, a magnetic disk such as a flexible disk or a hard disk, a CD-ROM / MO / MD / DVD, or the like. Optical discs, IC cards (including memory cards) / optical cards, etc., mask ROM, EPROM (Erasable Programmable Read Only Memory), EEPROM (Electrically Erasable Programmable Read Only Memory. Registered trademark), flash ROM It may be a medium such as a semiconductor memory that holds the program code fixedly.

  Further, in the present embodiment, since the system configuration is such that a communication network including the Internet can be connected, it may be a medium that carries the program code fluidly so as to download the program code from the communication network. When the program is downloaded from the communication network in this way, the program for downloading may be stored in the main body device in advance, or may be installed from another recording medium. 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.

  The recording medium is read by a program reading device provided in a digital color image forming apparatus or a computer system to execute the above-described image processing method.

  INDUSTRIAL APPLICABILITY The present invention is applied to a device capable of installing document reading software for reading a document image, or a device capable of mounting a document reading circuit for reading a document image. Examples of such a device include a digital multi-function peripheral, a copier, a scanner, and the like.

10 image input device 20 image output device 30 transmission / reception device 40 storage unit 50 control unit (CPU)
100 image processing device 110 binding device shadow detection unit 111 pixel determination unit 112 histogram generation unit 113 edge counting unit 114 character recognition processing unit 115 signal conversion unit 116 binarization processing unit 117 layout analysis unit 118 character recognition unit 119 binding device shadow candidate Detecting unit 120 Binding device shadow determination unit 130 525 625 Binding device shadow dedicated processing unit 131 Upside-down determination unit 132 Upside-down correction unit 133 Binding device shadow removal unit 500 600 Image forming apparatus 505 605 A / D conversion unit 510 610 Shading correction unit 515 615 Input processing unit 520 620 Automatic document type determination unit 530 630 Color correction unit 535 Area separation unit 540 Black generation / undercolor removal unit 545 Spatial filter unit 550 Output tone correction unit 555 Halftone generation unit 560 635 Formatting processing unit 570 650 Image processing device 701 Exposure unit 702 developing unit 703 photoconductor drum 704 cleaner unit 705 charger 706 intermediate transfer belt unit 707 fixing unit 710 transfer roller 711a 711b pickup roller 712a 712b 712c 712d transport roller 713 registration roller 761 intermediate transfer belt 762 intermediate transfer belt drive roller 763 Intermediate transfer belt Driven roller 764 Intermediate transfer roller 765 Intermediate transfer belt cleaning unit 771 Heat roller 772 Pressure roller 773 External heating belt 781 Paper feed cassette 782 Manual feed cassette 791 Paper ejection tray 792 Document placement table 810 Device body 820 Automatic document processing device

Claims (13)

For the four corner areas of the input image obtained by scanning the original,
Each of the plurality of pixels forming the region, a pixel determination unit that determines whether a solid pixel or an edge pixel,
A binding tool shadow candidate detection unit that detects a binding tool shadow candidate from a solid pixel group that is determined to be a solid pixel by the pixel determination unit,
An edge counting unit that calculates the number of pixels of pixels that have been determined to be edge pixels by the pixel determination unit;
When the region including the binding device shadow candidate detected by the binding device shadow candidate detection unit and having the number of edge pixels calculated by the edge counting unit within a predetermined range is one of the four corner regions A binding tool shadow determination unit that determines that the binding tool shadow candidate is an actual binding tool shadow,
An image processing apparatus comprising: Further comprising a character recognition processing unit for recognizing a character existing in each of the four corner regions,
The binding device shadow determination unit further determines that the binding device shadow candidate is an actual binding device shadow when the region in which the character recognition processing unit does not recognize a character is one of the four corner regions. The image processing apparatus according to claim 1, wherein the determination is performed.   The image processing apparatus according to claim 1, wherein the binding tool shadow candidate detection unit detects the binding tool shadow candidate based on a density histogram of the solid pixel group. The edge counting unit further detects a distribution region of edge pixels based on coordinate values of pixels determined to be the edge pixels by the pixel determination unit ,
The binding Gukage determination unit distribution region of the edge pixels are formed in a linear shape, that vertical direction of the angle of direction and the document of the line is within a predetermined range, the binding Gukage candidate The image processing apparatus according to any one of claims 1 to 3, wherein a further condition is set for determining that the shadow is an actual binding tool shadow.   The image according to any one of claims 1 to 4, wherein the top and bottom of the input image is determined by determining in which of the four corner regions the actual binding tool shadow exists. Processing equipment.   The image processing apparatus according to claim 1, wherein the actual binding tool shadow is deleted from the input image that is determined to have the actual binding tool shadow.   7. The color tone of the area after the actual binding tool shadow is deleted after the actual binding tool shadow is erased is matched with the color tone of the area other than the actual binding tool shadow. The image processing device described.   An image forming apparatus comprising the image processing apparatus according to claim 1. For the four corner areas of the input image obtained by scanning the original,
Each of the plurality of pixels forming the area is determined as a solid pixel or an edge pixel,
Detects binding tool shadow candidates from the solid pixel group determined to be solid pixels,
Calculate the number of pixels determined to be edge pixels,
When the region including the binding device shadow candidate and having the calculated pixel number of the edge pixels within the range between the first threshold value and the second threshold value is one of the four corner regions, An image processing method, characterized in that a binding tool shadow candidate is determined to be an actual binding tool shadow.   An image processing program for operating the image processing apparatus according to claim 1, wherein the image processing program causes a computer to function as each unit included in the image processing apparatus.   An image forming program for operating the image forming apparatus according to claim 8, wherein the image forming program causes a computer to function as each unit included in the image forming apparatus.   A recording medium having the image processing program according to claim 10 stored therein in a computer-readable manner.   A recording medium having the image forming program according to claim 11 stored therein in a computer-readable manner.

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