JP2003046771A - Image processor, image processing method, and imaging apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image processor, an image processing method, and an imaging apparatus capable of suppressing the deterioration of image quality in a photographic region while sharply outputting the character region of an original image. SOLUTION: This image processor discriminates whether or not the input image of the image information of an inputted original is a specific region, discriminates whether or not an image region other than the image region which is discriminated to be the specific region is the other region, discriminates the image region which is discriminated to be not the other region as the specific region, divides the input image into a plurality of regions, discriminates whether or not each divided image region is the specific region, executes image processing under the consideration of gradation to an image in the image region which is discriminated to be the specific region, executes image processing or enhancing definition to an image in the image region which is discriminated to be the other region, counts the number of pixels which is not less than the number of gradations being a prescribed threshold in each divided image region, and discriminates whether or not each image region is the specific region based on the counted number. Thus, the image region which is discriminated to be not the other region can be discriminated as the specific region, and the edge of the inside part of the photographic region can be separated from the character region, and the image processing under the consideration of gradation can be executed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus, an image processing method, and an image forming apparatus which read image information of a document and perform image processing according to the type of image in the same document.

[0002]

2. Description of the Related Art In a conventional color image processing apparatus,
A good image is obtained by discriminating the image area into a "dot area", a "photographic area", and a "character area" based on the characteristics of the picture on the image, and performing different image processing on each. This conventional discrimination method is shown in FIG. 7, in which it is discriminated whether or not the document image read by a scanner or the like is a halftone dot region for each predetermined region (S91), and the non-halftone dot region is a character region. It is determined whether or not (S92), and the area that is not a character is determined to be the photograph area.

According to the above-mentioned conventional discrimination method, an edge portion of a color close to an achromatic color in the photograph area is also discriminated as a character area, and is output only by K (black) regardless of the inside of the photograph or the character is in the photograph area. Image processing such as spatial filter processing with strong edge enhancement similar to that of the area has been performed. For this reason, the edge portion of the photograph and the boundary portion with the background portion are trimmed with K, or with a dark eye color due to edge enhancement, resulting in an unnatural photograph image, and the image quality of the photograph region is deteriorated. .

[0004]

SUMMARY OF THE INVENTION In view of the above-mentioned problems of the prior art, the present invention is directed to an image processing apparatus, an image processing method and an image processing apparatus capable of suppressing deterioration of image quality in a photograph area portion while sharply outputting a character area portion. An object is to provide a forming device.

[0005]

In order to achieve the above object, an image processing apparatus according to the present invention divides an input image into a plurality of areas in an image processing apparatus capable of inputting image information of a document. Determination means for determining whether or not each of the image areas thus determined is a specific area, and performing image processing with emphasis on gradation characteristics for the image in the image area determined to be the specific area, and Image processing means for performing image processing for enhancing the sharpness of the image in the image area determined to be the area, wherein the determination means is the number of gradations of a predetermined threshold value in each of the divided image areas. It is characterized in that the number of pixels described above is counted, and whether or not each of the image areas is a specific area is determined based on the counted number.

According to this image processing apparatus, since the gradation-oriented image processing can be performed on each divided image area determined to be the specific area, the specific area is, for example, a photograph area portion having many intermediate gradations. As a result, it is possible to prevent the image quality from deteriorating in the photograph area. In addition, an image area that is not determined to be a specific area and is determined to be another area is, for example, a character area portion,
Image processing different from other areas can be performed in the specific area, and deterioration in image quality in the photograph area can be suppressed.
Images in other regions can be output sharply by performing image processing such as edge processing for enhancing sharpness.

Further, it is determined whether an image area other than the image area determined to be the specific area is the other area, and the image area determined to be not the other area is determined to be the specific area. It is preferable to further include the determining means. It is determined whether the image area other than the image area determined to be the specific area is an area other than the specific area, and the image area determined to be not the other area is included in the specific area. The image area that has many gradations, the image area that is determined to be another area is the character area portion, and the image area that is determined not to be another area is, for example, a white background portion that does not include characters. Thus, the edge portion inside the photograph area portion can be separated from the character area portion. Therefore, image processing different from other areas can be performed in the specific area, and deterioration of image quality in the photograph area can be suppressed.

Further, by providing storage means for storing all pixel information for each of the divided image areas, the number of pixels is counted by the above-mentioned determination means after being stored in the storage means once. You can

Further, in the above-mentioned image processing apparatus, the number of pixels having a gradation value of a predetermined threshold value or more is counted in one line in each divided image area, and each image area is calculated based on the counted number. You may make it discriminate | determine whether is a specific area. One pixel is determined by the resolution of the sensor for reading the image information of the document.

Further, the discriminating means counts, for each line in each of the divided image areas, the number of pixels which is equal to or larger than the gradation number of a predetermined threshold value, and based on the counted number, each of the image areas is counted. By further including a storage means for determining whether or not the area is a specific area and storing only the count number, it is only necessary to count each line by the counter and store the count number for each line. It has a small capacity and is economical.

Further, the above-mentioned discriminating means can discriminate whether or not each of the image regions is a specific region, based on whether or not the count number is less than or equal to a predetermined threshold value.

Further, in the above-mentioned discriminating means, the gradation difference between the maximum gradation value and the minimum gradation value is obtained in each of the divided image areas, and the gradation difference is below a predetermined threshold value. Whether or not each of the image areas is a specific area may be further determined depending on whether or not the image area is a specific area.

In this case, the gradation difference between the maximum gradation value and the minimum gradation value is obtained for one line in each of the divided image areas,
By further determining whether or not each of the image areas is a specific area depending on whether or not the gradation difference is less than or equal to a predetermined threshold value, even a complicated character close to a solid image has a relatively large gradation difference. Therefore, it is possible to prevent it from being discriminated from the photograph area portion.

In the above case, the above threshold values can be changed and set so that the above determination can be made more appropriately.

Also, the discriminating means expands the image area discriminated as the specific area to a predetermined area around the image area, and discriminates the expanded image area as the specific area, thereby forming an image with corners. Even if it is in the photograph area portion, it can be accurately made into the specific area, and erroneous discrimination of the edge portion inside the photograph area portion can be prevented more effectively.

In this case, the predetermined area to be expanded is a predetermined number of images, and the number of pixels can be changed and set so that the erroneous determination can be more appropriately prevented.

Further, it is preferable that the image processing means performs image processing so that the image area discriminated as the specific area is output in a chromatic color.

Further, the image processing means further comprises another discriminating means for discriminating whether or not the image area is a periodical area, and the image processing means is an image for suppressing a moire phenomenon in the area discriminated as being periodical. It is preferable to perform the treatment. In this case, it is preferable that the priority of the area discrimination in each of the above-mentioned discrimination means is a region having a periodicity such as a halftone dot image, a specific region that emphasizes gradation, and another region that emphasizes sharpness.

Further, it is preferable that the input image is discriminated for each channel, and then the discrimination results for a plurality of channels are unified by a predetermined method, and then the image processing means performs the image processing. In this case, the predetermined method may use a logical sum or a logical product.

Further, the image processing method according to the present invention includes the step of inputting image information of a document, dividing the input image into a plurality of areas, and determining whether or not each of the divided image areas is a specific area. A step of determining whether or not an image area other than the image area determined to be the specific area is another area that is not the specific area, and an image area determined to be the other area is determined to be the specific area And a step of performing image processing with an emphasis on gradation on the image in the image area determined to be the specific area, and a step of performing image processing to enhance sharpness on the image in the image area determined to be the other area. And are included.

According to this image processing method, it is possible to perform gradation-oriented image processing on each divided image area determined to be a specific area, so that the specific area is, for example, a photographic area portion having many intermediate gradations. As a result, it is possible to prevent the image quality from deteriorating in the photograph area. Further, it is determined whether the image area other than the image area determined to be the specific area is an area other than the specific area, and the image area determined to be not the other area is included in the specific area. Is a photo area portion with many intermediate gradations, an image area determined to be another area is a character area portion, and an image area determined to be not another area is, for example, a white background portion that does not include characters. By doing so, the edge portion inside the photograph area portion can be separated from the character area portion. Therefore, by performing image processing that is different from the other areas in the specific area, it is possible to suppress deterioration in image quality in the photograph area portion. Images in other areas can be output sharply by performing image processing such as edge processing.

Further, in the discrimination step, the number of pixels having a gradation value of a predetermined threshold value or more is counted in each of the divided image areas, and each of the image areas is identified as a specific area based on the counted number. It can be determined whether or not. Furthermore,
It is preferable that a gradation difference between a maximum gradation value and a minimum gradation value is obtained in each of the divided image areas, and whether or not each of the image areas is a specific area is further determined based on the gradation difference. .

Further, in the discrimination step, the image area discriminated as the specific area is expanded to a predetermined area around the image area, and the expanded image area is discriminated as the specific area. It is possible to more effectively prevent erroneous determination of the edge portion inside.

Further, it is preferable that the input image is discriminated for each channel, and then the discrimination results for a plurality of channels are unified by a predetermined method, and then the respective image processing steps are executed.

An image forming apparatus according to the present invention is characterized by including the above-mentioned image processing apparatus and an image forming apparatus main body for forming an image based on image information processed by the image processing apparatus. According to this image forming apparatus,
It is possible to form an image on the recording medium or the like while suppressing the image quality deterioration of the image in the photographic region while forming a sharp image in the character region.

[0026]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a side view schematically showing an image forming apparatus combined with an image processing apparatus having a scanner function according to an embodiment of the present invention, and FIG. 2 is for processing read image data of the image processing apparatus of FIG. It is a block diagram of.

As shown in FIG. 1, the image processing apparatus includes a document table 20 on which a sheet-shaped document to be read is placed, and a feeding roller 19 for feeding the document from the document table 20 into the apparatus one by one. A plurality of conveying roller pairs 21 to 24 for conveying the originals on the conveying path 26, a discharge roller 25 for discharging the originals, and a discharge tray on which the originals discharged from the discharge rollers 25 are placed. 30 and a pair of conveying rollers 2
First platen glass 14 disposed between 3 and 24
An optical system 16 that is stationary and fixed immediately below the first platen glass 14 to read a document image, an imaging optical system 55,
The CCD image pickup device 56 and the second platen glass 15 for reading a document image from a stationary document are provided.

The image processing apparatus shown in FIG. 1 is designed to read an original image by the scanner function as follows. That is, the original image surface of the original S being conveyed by the pair of conveying rollers on the first platen glass 14 is irradiated with light from the light source 51, and the reflected light from the original image surface is reflected by the mirrors 52, 53, 54. By being guided and incident on the CCD image pickup device 56 via the image forming optical system 55, a document image is imaged and read on the light receiving surface of the CCD image pickup device 56. On the other hand, the original still on the second platen glass 15 is irradiated with light from the light source 51 while the entire optical system 16 moves in the direction f, and similarly, the CCD image pickup device 56.
Read in.

As shown in FIG. 2, the image processing apparatus is shown in FIG.
A / D conversion circuit 3 for converting an analog signal of image data photoelectrically converted by the CCD image pickup device 56 into a digital signal
1, a division unit 32 that divides a document image of a digital image into a plurality of predetermined small areas (for example, A pixels × B pixels in FIG. 4A), and a floor of each pixel in each divided image area. A comparison unit 33 that compares whether or not the number of tones is equal to or greater than a first threshold value (TH1), and a pixel that has a gradation number equal to or greater than a first threshold value (TH1) that is the comparison result of the comparison unit 33. A comparison unit 34 that counts the number of pixels and compares whether the total number of pixels is less than or equal to a second threshold value (TH2), and a gradation of a maximum gradation number and a minimum gradation number in each image area. The third difference is the third threshold (TH3)
Comparing unit 35 for comparing whether or not the following, and dividing unit 31
An expansion unit 36 that expands each image area divided by a predetermined number of pixels, and a determination unit that determines whether or not each image area is a photograph area portion based on the comparison results of the comparison units 34 and 35. And 37. The above-mentioned portions 31 to 37 constitute the photo discrimination unit 43, and discriminates whether or not the original image is a photo region.

The image processing apparatus shown in FIG. 2 determines the presence or absence of periodicity in a document image and determines whether or not it is a halftone dot area, and an edge portion to detect a character area. A character determination unit 42 for determining whether or not there is, and a determination result combining unit 38 for combining the determination results determined for the photograph area, the halftone dot area, or the character area as described above.

Further, the image processing apparatus shown in FIG.
Gradation-oriented image processing such as Y or CMYK is performed, and similarly, CMY or CMYK single colors are output for image areas that are character areas, and sharpness of edge enhancement by known spatial filter processing is performed. An image processing unit 40 that performs image processing that enhances the image processing and also performs known spatial filter processing that prevents the moire phenomenon in the image area that is the halftone dot area portion, and the image processed by the image processing unit 40. And a memory 39 for storing data.

Further, each of the comparing sections 33 to 35 is provided with a comparator such as a comparator, and the first to third threshold values (TH
1 to TH3) can be set by changing the reference value of each comparator. Further, the number of pixels to be expanded by the expansion unit 36 can be changed and set.

Further, in image formation, the image data in the memory 39 is sent to the image writing unit 60 of the image forming apparatus via the image processing unit 38. The image writing unit 60 writes, for example, an electrostatic latent image on the photoconductor, develops the electrostatic latent image, and transfers and fixes it on a recording sheet to form an image. Alternatively, the image data in the memory 39 may be sent to an inkjet printer to form an image on recording paper.

Next, the image processing apparatus shown in FIGS. 1 and 2 including its operation will be further described with reference to FIGS.

In the present embodiment, the character area is "characters written on a white background portion of the document", and the characters written on a non-white background such as inside a photograph is outside the character area. In addition, the photographic area is defined as "area in which the number of white background gradation pixels is small in an arbitrary small area in the original image", and the halftone dot area is an image area composed of a large number of halftone dots formed with periodicity. To do.

In the image processing apparatus shown in FIGS. 1 and 2, the original information is read by the CCD image pickup device 56 by the scanner function and the A /
The D conversion circuit 31 produces a digital signal, and the halftone dot discriminating unit 41 of FIG. 2 discriminates whether or not the digital image has a periodicity. The character discriminating unit 42 detects an edge portion to determine whether the digital image is a character region. Whether or not it is a photograph area is determined by the photograph discrimination unit 43 as described later. Each such discrimination is
The halftone dot discriminating unit 41, the character discriminating unit 42, and the photograph discriminating unit 43 are independently performed.

Next, the step of synthesizing the result of the area discrimination of the original image as described above by the discrimination result synthesizing section 38 of FIG. 2 will be described with reference to FIG. FIG. 3 is a flowchart showing the basic steps of the area discrimination processing for synthesizing the discrimination result of discriminating the original image into the halftone dot area, the photograph area or the character area as described above.

First, the image area determined by the halftone dot discriminating section 41 to be a halftone dot area is set as a halftone dot area (S01), and the image area determined not to be the halftone dot area is set as a photographic area by the photographic area discriminating section 43. The area is defined as a photograph area (S02), and the area defined as a character area by the character area determination unit 42 is defined as a character area in the image area determined not to be the photograph area (S03).

Then, the image area which is determined not to be the character area in step S03 is set as a photograph area. As a result, an area that has not been determined as a character area (a white background portion that does not include characters) is determined as a photograph area again, and the edge portion inside the photograph can be separated from the character area.

Next, the photographic area discrimination algorithm in step S02 of FIG. 3 will be described with reference to FIGS. In this image area discrimination, the edge portion inside the image is outside the character area in the image processing apparatus that mainly performs color digital image processing.

FIG. 4 is a diagram (a) showing pixels (A × B) in one image area obtained by dividing the image area which is the photograph area, and a conceptual diagram (b) when expanding the image area which is the photograph area. )
5 is a diagram showing an effect when the image region is expanded as shown in FIG. 4B, and FIG. 6 is a flowchart showing each step of the photographic region discrimination processing.

First, as shown in FIG. 6, the CCD image pickup device 56.
As shown in FIG. 4A, the digital image having the document information read by the digital signal as a digital signal is divided into small areas C (A (pix.) × B (pix.)) Of a predetermined size. The pixel value (the number of gradations of 0 to 255) of each pixel in this small region C is checked, and the number of gradations of each pixel is determined by the comparison unit 33 to be the first threshold value TH.
It is compared whether it is 1 or more (S11). This first threshold TH1 is preferably set based on the background gradation of the original.

Next, the comparing section 34 counts the number of pixels having the gradation number equal to or higher than the first threshold value TH1 in the small area C, and the counted number of pixels is the second threshold value. TH2
It is compared whether or not the following (S12). Step S12
With respect to the small area C in which the number of pixels counted in 2 is equal to or less than the second threshold value TH2, the gradation number difference between the maximum gradation number and the minimum gradation number in the small area C is calculated, and this gradation is calculated. The comparison unit 35 compares the number difference with the third threshold value TH3 or less (S13).

The small area C, in which the difference in gradation number is equal to or less than the third threshold value TH3 in step S13, is set as a photographic area. Further, the small area C is vertically, horizontally and horizontally shown in FIG. 4B. Is expanded by the number of pixels set in advance (S14), and the area C'including this expanded area is set as a photographic area.

In the discrimination algorithm up to step S12 in FIG. 6, in the case of a normal character, the number of pixels counted is equal to or greater than the second threshold value TH2 because the dark area is larger than the photographic area having many intermediate gradations. However, a complicated character such as "cloudy" may be detected as a solid image portion rather than a character area because the density of the background portion of the document is relatively high. Therefore, in step S13, it is determined whether the difference in the number of gradations in the small area is equal to or smaller than the third threshold value TH3, and T
The case of H3 or less is defined as the photographic area. However, since a complicated character such as "cloudy" has a larger gradation difference than the photographic area, it becomes TH3 or more and can be excluded from the photographic area.

The size (number of pixels) of A and B of the divided small area C can be set to any size, but if it is small, the inside of a bold character or the like cannot be detected and cannot be discriminated from the character area to some extent. Is required, and therefore A, B
It is preferable to change the number of pixels in (1) depending on how many characters are used so as not to be erroneously determined. The size of one pixel is determined by the resolution of the CCD image pickup device 56 shown in FIG.

The small area C, which is determined to be a photograph area, is
In step S14, it is expanded vertically and horizontally as shown in FIG. 4B. This effect will be described with reference to FIG. As shown in FIG. 5A, when the photographic area D of the document has a corner D1, the small area C in FIG. 4 is a quadrangle, so the corner D in FIG.
As shown in the enlarged view of No. 1, the area up to the area D2 can be used as the photographic area, but the corner such as the portion D3 near the top cannot be detected and is outside the photographic area. On the other hand, step S14 of FIG.
Since the small area C is expanded to the area D4 so as to include a corner such as the top vicinity portion D3 as shown in FIG. 5C, every corner of the corner D can be a photograph area. In this way, the photo area in the original image can be identified.

The small area C in which the number of pixels counted in step S12 of FIG. 6 is equal to or larger than the second threshold value TH2 and the difference in gradation number is the third threshold value TH in step S13.
With respect to the small area C of 3 or more, it may be determined whether or not it is a character area in the character determination area 42 of FIG. 2 (S15).

Next, as described with reference to FIG. 3, the halftone dot area, the photograph area and the character area which are distinguished by distinguishing the original image by the distinction result combining section 38 of FIG. 2 are shown in FIG.
At 0, image processing is performed by each method. That is, the halftone dot area is subjected to image processing to prevent the moire phenomenon, the photographic area is subjected to gradation-oriented image processing such as outputting in CMY or CMYK, and the character area is output in CMY or CMYK single colors. Image processing is performed to enhance the sharpness of edge enhancement. In this way, for example, the black character area is sharply output with K toner as before, and the inside of the photograph is CM.
It is possible to perform image processing that emphasizes gradation by YK output.

Further, as shown in FIG. 3, the area determined to be a character area in step S03 becomes a character area, and the area not determined to be a character area (a white background portion that does not include a character).
Is again discriminated as a photographic region. Thus, by positively discriminating the photographic region as compared with the conventional processing, a monochromatic output such as K due to an erroneous discrimination of the edge portion inside the photograph, etc. Therefore, it is possible to output a better photographic image when the original includes a photograph.

The image processing apparatus shown in FIG. 2 is provided with a counter for counting the number of pixels equal to or greater than the threshold number of gradations for each line in each divided image area. It is also possible to determine whether each image area is a photographic area based on the determination result and store the determination result for each one line in the memory 39. The stored content can be read out from the memory 39 and the determination processing can be performed in the same manner as described above. In this case, the memory 39 only needs to count each line by the counter and stores the number of counts for each line. Therefore, the capacity of the memory is small, the capacity of the memory does not increase, and the cost of the apparatus increases. I won't. Further, when the input image is input through a plurality of color channels, the determination is performed for each color channel, and then the determination results of the plurality of color channels are subjected to the logical sum or the logical product by the determination unit 37 of FIG. After unifying with, each image processing is performed.

As described above, according to the image processing apparatus of the present embodiment, a halftone dot area having periodicity is discriminated from the original image, and then a photograph area is discriminated by a new simple method to take a photograph. By separating the inner edge part from the character area, the black character area part can be output sharply with K toner as before, and even if the inside of the photograph is a part close to black, it can be CMY or CMYK chromatic colors. Since it is possible to perform image processing that emphasizes gradation by output, it is possible to suppress deterioration in image quality in the photographic area.

Next, an electrophotographic color image forming apparatus incorporating the above image processing apparatus will be described with reference to FIG. As shown in FIG. 1, the image forming apparatus 70 is provided with the image processing apparatus having the above-mentioned scanner function on its upper portion, and the image writing unit 60 of FIG. 2 is provided on the lower portion of the image reading apparatus. Further, the image forming apparatus 70 includes a photosensitive drum 71 that is exposed by a laser beam modulated based on an image processing signal in the image writing unit 60 to form a latent image, and a charger that is arranged around the photosensitive drum 71. 72, developing device 73, transfer devices 74, 7
5, a cleaning unit 76. Although only one developing device 73 is shown in FIG. 1, a plurality of developing devices 73 are provided for CMYK.

In the image forming apparatus 70 of FIG. 1, an image is formed on the recording paper 30 as follows. Laser light from the image writing unit 60 is exposed to the rotating photosensitive drum 71 to form a latent image, and the latent image is toner-developed by a plurality of developing devices 73. Paper feed cassette OA or OB at the bottom of FIG.
Recording paper 30 sent from above by a pair of transport rollers
Is synchronized with the rotation of the photosensitive drum 71 by the pair of conveying rollers 61 and the photosensitive drum 71 and the transfer devices 74 and 75 are timed.
And the developed image is transferred to the recording paper. Next, the recording paper is conveyed by the conveyor belt 77 in the direction of the arrow in the figure, and the toner image is fixed by the fixing device 78 to form an image on the recording paper.

When the recording paper is finished with one-sided image formation, the conveyance roller pair 8 is operated by the operation of the conveyance direction switching member 81.
5 is discharged to the discharge unit 80. When an image is formed on the opposite side of the recording paper, the conveyance direction switching member 81
Is activated and the recording paper is sent to the lower reversing unit 83 by the reversing roller pair 82 and the like, and then is sent upward, passes through the conveying unit 84, and is conveyed below the photosensitive drum 71 in a reversed state.
Similarly, an image is formed on the opposite surface, and then the image is discharged to the discharge unit 80.

Since the above-described color image forming apparatus includes the image processing apparatus described with reference to FIGS. 1 to 6, even if the original includes the photographic area, the edge portion inside the photograph is emphasized to create an unnatural image. Therefore, it is possible to form an image on the recording paper in which the deterioration of the image quality is suppressed.

Although the present invention has been described above with reference to the embodiments, the present invention is not limited to these.
Various modifications are possible within the scope of the technical idea of the present invention. For example, it goes without saying that the image processing apparatus can be configured as a single apparatus that is not combined with the image forming apparatus. Also,
The CCD image pickup device may be a light receiving unit configured by arranging light receiving elements in a line. Further, the image processing apparatus does not have to have a scanner function in particular, as long as the image information of the read document can be input from the outside.

[0058]

According to the image processing apparatus, the image processing method and the image forming apparatus of the present invention, it is possible to sharply output the character area portion or the like in the original image while suppressing the deterioration of the image quality in the photograph area portion or the like.

[Brief description of drawings]

FIG. 1 is a side view schematically showing an image forming apparatus combined with an image processing apparatus having a scanner function according to an embodiment of the present invention.

FIG. 2 is a block diagram for processing read image data in the image processing apparatus of FIG.

FIG. 3 is a flowchart showing the basic steps of a region discrimination process for synthesizing a discrimination result in which a document image is discriminated as a halftone dot region, a photograph region, or a character region in the image processing apparatus shown in FIGS. 1 and 2.

FIG. 4 is a diagram (a) showing pixels (A × B) in one image region divided by the division unit of FIG. 2 and a conceptual diagram (b) when expanding the image region.

5 (a) and 5 (b) are diagrams showing an effect when the image region is expanded as shown in FIG. 4 (b), and FIG. 5 (a) is a diagram of a document image showing a photographic region including a corner portion. FIG. 5B is an enlarged view for explaining the reason why all the corners cannot be detected.
(C) is a figure for demonstrating that a corner can be detected to every corner by area expansion.

FIG. 6 is a flowchart showing a photographic area discrimination step in the area discrimination processing of FIG. 3;

FIG. 7 is a flowchart showing a conventional image area determination method.

[Explanation of symbols]

31 A / D conversion circuit 32 divisions 33-35 comparison section 36 Extension 37 Discriminator 38 Discrimination result composition unit 39 memory 40 Image processing unit 41 Halftone dot discriminator 42 Character discriminator 43 Photo Area Discriminator 56 CCD image sensor 60 Image writing section 70 image forming apparatus S manuscript Number of A and B pixels C divided small area C'extended small area

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Claims (21)

[Claims] 1. An image processing apparatus capable of inputting image information of an original, dividing an input image into a plurality of areas, and determining whether or not each of the divided image areas is a specific area; Image processing that performs tone-oriented image processing on an image in an image area determined to be an area and image processing that enhances sharpness on an image in an image area that is not determined to be the specific area and is determined to be another area The determining means counts the number of pixels having a gradation value of a predetermined threshold value or more in each of the divided image areas, and identifies each of the image areas based on the counted number. An image processing apparatus characterized by determining whether or not it is a region. 2. An image area other than the image area determined to be the specific area is determined to be the other area, and an image area determined to be not the other area is determined to be the specific area. The image processing apparatus according to claim 1, further comprising: a determining unit. 3. The image processing apparatus according to claim 1, further comprising a storage unit that stores all pixel information about each of the divided image areas. 4. The number of pixels equal to or more than a predetermined threshold gradation number is counted in one line in each of the divided image areas,
4. It is determined whether or not each image area is a specific area based on the count number.
The image processing device according to item 1. 5. The discriminating means counts the number of pixels equal to or more than a gradation number of a predetermined threshold value for each line in each of the divided image areas, and based on the counted number, each of the image areas is counted. The image processing apparatus according to claim 1 or 2, further comprising a storage unit that determines whether or not is a specific area and stores only the count number. 6. The method according to claim 1, wherein whether or not each of the image areas is a specific area is determined based on whether or not the count number is equal to or less than a predetermined threshold value. The image processing device described. 7. The discriminating means obtains a gradation difference between a maximum gradation value and a minimum gradation value in each of the divided image areas, and whether the gradation difference is a predetermined threshold value or less. The image processing apparatus according to claim 1, further comprising determining whether each of the image areas is a specific area or not. 8. A gradation difference between a maximum gradation value and a minimum gradation value is obtained for one line in each of the divided image areas, and whether or not the gradation difference is less than or equal to a predetermined threshold value. The image processing apparatus according to claim 7, wherein it is further determined whether or not each of the image areas is a specific area. 9. The image processing apparatus according to claim 1, wherein each of the threshold values can be changed and set. 10. The image area determined as the specific area is expanded to a predetermined area around the image area, and the expanded image area is determined as the specific area. The image processing device according to item 1. 11. The image processing apparatus according to claim 10, wherein the predetermined area to be expanded is a predetermined number of images and can be set by changing the number of pixels. 12. The image processing means performs image processing such that an image area determined to be the specific area is output in a chromatic color.
The image processing device according to item. 13. The image processing means further comprises another determining means for determining whether or not the image area has a periodicity, and the image processing means defines the area determined to have the periodicity as the specific area. The image processing apparatus according to claim 1, further comprising image processing for suppressing a moire phenomenon. 14. The input image is discriminated for each channel, and then the discrimination results for a plurality of channels are unified by a predetermined method, and then the image processing means performs the image processing. Any one of 1 to 13
The image processing device according to item. 15. The image processing apparatus according to claim 14, wherein the predetermined method uses a logical sum or a logical product. 16. A step of inputting image information of an original, a step of dividing the input image into a plurality of areas, and determining whether or not each of the divided image areas is a specific area, and determining the specific area. A step of determining whether the image area other than the specified image area is another area that is not a specific area, a step of determining an image area that is determined not to be the other area as a specific area, and the specific area A step of performing gradation-oriented image processing on the image in the determined image area, and a step of performing image processing for enhancing the sharpness of the image in the image area determined to be the other area. Image processing method. 17. The number of pixels having a gradation value of a predetermined threshold value or more is counted in each of the divided image areas, and it is determined whether or not each of the image areas is a specific area based on the counted number. The image processing method according to claim 16, wherein: 18. A gradation difference between a maximum gradation value and a minimum gradation value is calculated in each of the divided image areas, and whether each of the image areas is a specific area is further determined based on the gradation difference. The image processing method according to claim 16 or 17, wherein the image processing method is a discrimination. 19. The image area determined as the specific area is expanded to a predetermined area around the specific area in the determination step, and the expanded image area is determined as the specific area. The image processing method according to 16, 17, or 18. 20. The input image is discriminated for each channel, the discrimination results for a plurality of channels are unified by a predetermined method, and then the image processing steps are executed. 20. The image processing method according to any one of items 1 to 19. 21. An image processing apparatus according to claim 1, an image forming apparatus main body that forms an image based on image information image-processed by the image processing apparatus,
An image forming apparatus comprising: