JPH1097664A - Region extraction method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce influences caused by the conveyance nonuniformity, inclination or lateral deviation of a printed matter and to highly accurately extract a target area by calculating plural blocks having specified width in the main scanning direction of image data of the printed matter and extracting a specified area, namely, a white area in the image of the printed matter while using a shading histogram calculated in the main scanning direction for each block. SOLUTION: The image data of all the lines on one side of a printed matter P are read by an image input part 101, digitized by an A/D converting part 102 and binarized with a fixed threshold value by a binarizing processing part 103. Then, the respective blocks having specified main scanning width are calculated based on the binarized image data by a block calculating part 104, and the shading histograms in the main scanning (lateral) direction and subscanning (longitudinal) direction are calculated for each block by a shading histogram calculating part 105. Further, the area except for patterns (graphics) or characters (white area) is extracted by an area extracting part 106 while using the shading histograms.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for extracting a specific area on a printed matter, and more particularly, to an area extracting method used for detecting a print defect or a stain on a printed matter in which the position of a character or a pattern is known in advance. .

[0002]

2. Description of the Related Art In a conventional area extraction method, a distance from each end is defined in advance with respect to both ends (left, right, up and down) of a printed matter, and a target area is extracted using the distance. ing. In this case, the contrast between both ends of the printed matter and the background is increased so that both ends of the printed matter can be easily extracted.

[0003]

In the conventional method, the positions of both ends of the printed material are shifted due to uneven transport, folding, inclination, lateral displacement and dirt of the printed material. As a result, the distance of the target area from the edge of the printed material is reduced. And there is a problem that a target area cannot be accurately extracted.

Accordingly, the present invention reduces the influence of unevenness of conveyance, inclination and lateral displacement of a printed matter, and achieves higher accuracy than a conventional method of extracting an area to be extracted at a distance from only the upper, lower, left and right edges of the printed matter. It is another object of the present invention to provide a region extraction method capable of extracting a target region.

[0005]

In order to solve the above-mentioned problems, a region extracting method according to the present invention calculates a plurality of blocks having a specific width in the main scanning direction based on image data of a printed material, and calculates each block. A projection histogram in the main scanning direction is calculated for each block, and a specific area, that is, a white area in the print image is extracted using the projection histogram.

Further, the area extracting method according to the present invention is a method for extracting a specific area of a target printed matter, comprising: an image inputting step of inputting image data of the printed matter; A block calculation step of calculating a plurality of blocks having a specific main scanning width, a projection histogram calculation step of calculating a projection histogram in the main scanning direction for each block obtained from the block calculation step, An area extracting step of extracting the specific area using the projection histogram obtained from the projection histogram calculating step.

According to a second aspect of the present invention, in the method for extracting a specific area of a target printed matter, an image inputting step of inputting image data of the printed matter, and an image data obtained in the image inputting step are performed. An overlap block calculation step of calculating a block in which a block having a specific main scanning width is overlapped,
A projection histogram calculation step for calculating a projection histogram in the main scanning direction for each block obtained from the overlap block calculation step; and an area extraction for extracting the specific area using the projection histogram obtained from the projection histogram calculation step And the step is provided.

According to a second aspect of the present invention, there is provided a method for extracting a specific area of a target printed matter, comprising the steps of: inputting image data of the printed matter; Based on the main scanning width storage step to be registered as and the image data obtained in the image input step, a block corresponding to the main scanning width of the pattern known in advance by the main scanning width storage step is calculated. A variable block calculation step, a projection histogram calculation step of calculating a projection histogram in the main scanning direction for each block obtained from the variable block calculation step, and the specific area using the projection histogram obtained from the projection histogram calculation step. And an area extraction step of extracting

In the method for extracting a specific region of a target printed matter, an image inputting step for inputting image data of the printed matter, and an image data obtained in the image inputting step may be performed. A block calculation step of calculating a block having a specific main scanning width, a main scanning width storage step of registering a main scanning width of a known pattern as a dictionary, and the main scanning width storage step. From the step, for a specific block, a projection histogram in the main scanning direction is calculated for each block obtained in the block calculation step, and in another block, the block obtained in the block calculation step is added to the block. Projection histogram calculation that divides the existing pattern into blocks according to the main scanning width and calculates the projection histogram in the main scanning direction And steps, characterized by comprising a region extraction step of extracting the specific region using projection histograms obtained from the projection histogram calculation step.

Further, in the block calculation step of the region extraction method according to the present invention, the image data obtained in the image input step is binarized to distinguish between black pixels and white pixels.
The projection histogram calculating step includes a sub-scanning direction projection histogram calculating step of calculating a projection histogram in the sub-scanning direction for an area where white pixels and black pixels coexist. Extracting a specific region using a projection histogram in a scanning direction.

In the area extracting step of the area extracting method according to the present invention, in the area where white pixels and black pixels are mixed in the projection histogram, an area where the number of black pixels is equal to or less than a predetermined value is defined as the specific area. The method includes the step of extracting.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an area extracting method according to the present invention for extracting a specific area of a printed matter will be described below with reference to the drawings. FIG. 1 is a block diagram of an area extraction system according to the first embodiment of the present invention. Also, FIG.
5 is a flowchart illustrating a processing method of the region extraction system according to the embodiment of the present invention.

For a printed matter P, for example, image data of all lines on one side of the printed matter is read by an image input unit 101 such as a line sensor, and the read image data (analog signal) is digitally converted by an AD conversion unit 102. And further binarized by the binarization processing unit 103 using a fixed threshold. Based on the binarized image data, each block having a specific main scanning width is calculated by the block calculating unit 104, and based on the calculated block, the block is calculated by the projection histogram calculating unit 105. The projection histograms in the main scanning direction (hereinafter, horizontal direction) and the sub-scanning direction (hereinafter, vertical direction) are calculated for each of them. Further, the region extracting unit 10
In step 6, regions other than patterns (graphics) and characters are extracted using the projection histogram. In this case, the region to be extracted is a white region. A known white area on the print,
The extracted white areas are compared, and stains, print defects, and the like in the white areas are detected in a later process. However, the present invention aims to extract white areas.

Hereinafter, each processing unit will be described in detail. The image input unit 101 collects image data of the entire printed matter as an analog signal. Here, a case where the printed matter is transported to read the image data will be described as an example, but the same applies to a case where the light receiving unit is scanned and read.

FIG. 3 shows the configuration of the image input unit 101. As shown in FIG. 3, the image input unit 101 includes the light receiving unit 20.
1, a light source 202 for illumination, and a reference plate 203, which are arranged at the positions shown in FIG. Light receiving unit 201
, The reflected light is input vertically from the printed material P, or in the case where the light source 202 is arranged below the printed material P, the transmitted light is input to the light receiving unit 201. The illumination light source 202 is provided so as to avoid an angle from a line L connecting the printed matter P and the light receiving unit 201 to be close to 0 ° or 90 °, for example, installed between an angle of 30 ° to 60 °. I do. Although FIG. 3 illustrates a case where illumination is performed from the traveling direction with respect to the transport direction, illumination may be performed from behind.

The printed matter P is conveyed by rollers as shown in FIG. 3, and the reference plate 203 is arranged on the back of the printed matter P from which image data is read. This reference plate 203
Will be specifically described by taking the printed matter shown in FIG. 4 as an example. FIG. 4 is an image in which various rectangular patterns (graphics), characters, and the like are printed on white paper with ink other than white.
The region to be extracted is a hatched region shown in FIG. 6, that is, a region other than the rectangular pattern region and the character region of the image data.

First, the reference plate 203 arranged on the background of the printed matter P is a color having a high contrast to the printed matter paper, for example, black in the case of white paper as shown in FIG.
This is so that the position of the printed matter P can be easily determined when analyzing the image data. This reference plate 2
03 is a case where a printed matter P having printing on the front and back is transported,
The material must be resistant to contamination so that the ink does not adhere and the contrast is not reduced.

The AD conversion unit 102 includes an image input unit 101
To convert the image data (analog signal) fetched in step into a digital signal. In the binarization processing unit 103,
The grayscale image data (digital signal) obtained by the AD converter 102 is converted into binary data. Binarization is performed by a known method of binarizing a grayscale image, such as "Otsu's discriminant analysis method". Here, on the surface image data, the value “1” is a sentence or a figure, and the value “0” is a sheet. The background portion of the printed matter P is
A process is performed so that the value becomes “1”.

The block calculator 104, the projection histogram 105, and the region extractor 106 extract the left corner of the printed matter P (step 11 in FIG. 2), and calculate the horizontal projection for each block from the left corner (FIG. 2). Step 12 of 2). Next, a white area is extracted from the calculated projection histogram (step 13 in FIG. 2), and further, a black area and a white area are mixed using a vertical projection histogram (step 14 in FIG. 2). A white region is extracted from the region (step 15 in FIG. 2). As described above, the area to be extracted is extracted using the projection processing for each divided block.

Next, this projection processing will be described in detail. The block calculation unit 104 first extracts the position (coordinates) of one of the left and right corners in the main scanning direction, for example, the left corner (point A) in FIG. When extracting the position (coordinates) of the left corner (point A), the image data is scanned one line at a time from the upper left in the main scanning direction and the sub-scanning direction until the left corner (point A) is found. For example, the size of the image data is M × N (pixels), and the density value at each pixel is Fij (0 ≦ i <
M, 0 ≦ j <N. Assuming that Fij = “1” or “0”), as shown in FIG. 8, first, only one line is searched from the upper left of the image in the main scanning direction, and a pixel position where Fij = 1 (hereinafter, referred to as “Fij = 1”).
(Referred to as a start position). If not detected,
The next line is searched in the same manner as described above, and the left corner (point A) is detected. The “search for one line” means that, for example, when searching from the upper left to the right, the values of i and j of Fij are changed to 0 ≦ i <M with j = 0. .

Next, based on the left corner (point A), for example, FIG.
, A block having a size of main scanning width w × sub-scanning width h is calculated. Here, both w and h are represented by the number of pixels. Further, the projection histogram calculation unit 105 calculates a horizontal projection histogram for each block calculated by the block calculation unit 104.

Here, the main scanning width w of the block is determined by the number of pixels in the vertical direction between the rectangular patterns and the maximum rotation angle of the printed matter P. For example, the number of pixels in the vertical direction of the region to be extracted,
That is, the number of pixels in the vertical direction between the rectangular patterns is c, and the printed matter P
Is the maximum rotation angle of θ, tan θ = c / w. Therefore, the main scanning width w of the block is calculated by w = c / tan θ. Here, the main scanning width of the block is w
Need not be fixed, and may be set to a value smaller than w. As a result, the number of regions to be extracted increases and the accuracy is improved. The sub-scanning width h of the block is the vertical width of the image data.

FIG. 10 shows an example of a projection histogram of a certain block in the main scanning direction. In FIG. 10, for example, a portion “D” indicates a pattern (graphic) region, and a portion “H” indicates a region other than the pattern (graphic) (here, a region to be extracted). Further, since the area other than the printed matter P, that is, the background area is set to the value “1” by the binarization processing unit, it appears in the projection histogram as a hatched portion in FIG.

In the area extracting section 106, the area where the cumulative number of black pixels is “0”, that is, a white area (“H” in FIG. 10) is obtained from the projection histogram for each block obtained from the projection histogram calculating section 105. Part). When the cumulative black pixel is equal to or less than (w-1), the projection histogram in the sub-scanning direction is calculated in the area ("C" in FIG. 10). FIG. 11 shows an example of a projection histogram in the sub-scanning direction. From this projection histogram,
In the same manner as described above, an area where the cumulative number of black pixels is “0”, that is, a white area (“L” in FIG. 11) is extracted.

Further, since the image data may include noise as shown in FIG. 12, for example, the cumulative black pixel number is not set to "0" in the projection histograms in the main scanning direction and the sub-scanning direction. For example, by extracting a region equal to or smaller than "1" or a region equal to or smaller than "2" as a white castle, it is possible to accurately extract a region to be extracted.

Here, the reason why the white area is extracted by using the projection histogram in the sub-scanning direction when the cumulative black pixel is equal to or less than (w-1) will be described. When the cumulative number of black pixels is equal to or less than (w-1), for example, FIG.
As shown in (a), when not only a rectangular pattern area but also a pattern (graphic) or character other than a rectangle exists in the printed matter P, or a rectangular pattern area exists but the width in the main scanning direction is (w−
1) If not, a projection histogram as shown in FIG. 13B is calculated. Therefore, an area such as a hatched area in FIG. 13A (an area in which a black area and a white area are mixed in the main scanning direction in a block) cannot be extracted only by the histogram in the main scanning direction. In this case, by setting the cumulative number of black pixels to (w-1) or less as described above, FIG.
As a result, the shaded area shown in FIG.

Next, a second embodiment of the present invention will be described. FIG. 14 is a block diagram of a region extracting method according to the second embodiment of the present invention. The image input unit 301, the AD conversion unit 302, and the binarization processing unit 303 are the same as the image input unit 101, the AD conversion unit 102, and the binarization processing unit 103 in the first embodiment. The overlap block calculation unit 304 calculates a block having a certain specific main scanning width by overlapping, and the projection histogram calculation unit 305 calculates a main block for each overlapped block based on the calculated block. A projection histogram in the scanning direction and the sub-scanning direction is calculated. Further, the region extraction unit 306 uses the projection histogram to generate a pattern (figure).
And areas other than characters.

Hereinafter, the overlap block calculating section 3
04, the projection histogram calculation unit 305, and the region extraction unit 30
The specific processing method 6 will be described. The overlap block calculation unit 304 extracts the left corner of the printed matter P, and calculates a block obtained by overlapping a block having a specific main scanning width from the left corner. Next, the projection histogram calculation unit 305 calculates the projection in the main scanning direction for each of the overlapped blocks. next,
The area extraction unit 306 allows the projection histogram calculation unit 30
The white area is extracted from the projection histogram calculated in step 5, and further, using the projection histogram in the sub-scanning direction,
A white region is extracted from a region where a black region and a white region are mixed. As described above, a region to be extracted is extracted using the projection processing for each block in which a block having a certain specific main scanning width is overlapped.

The overlap block calculating section 30 will now be described.
4 will be described. The method of extracting the position (coordinates) of one of the left and right corners in the main scanning direction in FIG. 7, for example, the left corner (point A), is the same as in the first embodiment.

Next, based on the left corner (point A), the main scanning width w
The projection histogram in the main scanning direction is calculated for each block having the size of the sub-scanning width h, and a block (see FIG. 15) in which each block is overlapped is calculated. That is, the first block is, for example, the left corner (point A)
Assuming that the block has a main scanning width w separated by S from the second
For example, a block having a main scanning width w at a distance of S + (w / 2) in the main scanning direction from the left corner (point A) is calculated.

The projection histogram calculation unit 305 calculates a projection histogram in the main scanning direction for each block obtained by the overlap block calculation unit 304. Here, similarly to the first embodiment, the main scanning width w of the block is determined by the number of pixels between the rectangular patterns in the sub scanning direction and the maximum rotation angle of the printed matter P. For example, if the number of pixels in the sub-scanning direction of the region to be extracted, that is, the number of pixels in the sub-scanning direction between rectangular patterns is c, and the maximum rotation angle of the printed matter P is θ,
The main scanning width w of the block is calculated by w = c / tan θ. The sub-scanning width of the block is h.
The vertical width of the image data.

The region extracting unit 306 extracts a region where the cumulative number of black pixels is "0", that is, a white region, from the projection histogram in the main scanning direction for each block, as in the first embodiment. When the cumulative black pixel is equal to or less than (w-1), the projection histogram in the sub-scanning direction is calculated in the area. From this projection histogram, an area where the accumulated black pixels are “0”, that is, a white area is extracted as described above.

Further, since the image data sometimes includes noise as shown in FIG. 12, for example, the accumulated black pixel number is not set to "0", but is set to, for example, an area of "1" or less or "2" or less. By extracting the region as a white region, it is possible to accurately extract the region to be extracted. Also,
The reason why the white area is extracted using the projection histogram in the sub-scanning direction when the cumulative black pixel is equal to or less than (w-1) is the same as in the first embodiment.

Next, a third embodiment of the present invention will be described. FIG. 16 is a block diagram of an area extracting method according to the third embodiment of the present invention. The image input unit 401, the AD conversion unit 402, and the binarization processing unit 403 are the same as the image input unit 101, the AD conversion unit 102, and the binarization processing unit 103 in the first embodiment. The main scanning width storage unit 407 registers the main scanning width of the pattern known in advance as a dictionary. Variable block calculator 404 and main scanning width storage 40
7, a block having a main scanning width corresponding to each pattern (pattern) and characters of the printed matter P is calculated, and the projection histogram calculation unit 405 calculates a block based on the calculated blocks.
Projection histograms in the main scanning direction and the sub-scanning direction are calculated for each block. Further, the region extracting unit 406 extracts regions other than patterns (graphics) and characters using the projection histogram.

A specific processing method of the variable block calculation unit 404, the projection histogram calculation unit 405, the area extraction unit 406, and the main scanning width storage unit 407 will be described below. The main scanning width storage unit 407 stores the main scanning width of a pattern (figure) or character of the printed matter P from the left corner. The variable block calculating unit 404 extracts the left corner of the printed matter P and calculates each block corresponding to the pattern (graphics) of the printed matter P and the main scanning width of the character based on the information from the main scanning width storage unit 407. I do. Further, the projection histogram calculation unit 405 calculates the projection in the main scanning direction for each block. Next, a white area is extracted from the calculated projection histogram, and further,
Using the projection histogram in the sub-scanning direction, a white region is extracted from a region where a black region and a white region are mixed. As described above, the region to be extracted is extracted by using the projection process for each block corresponding to the pattern (graphics) of the printed matter P or the main scanning width of the character.

The processing in the variable block calculator 404 will be described below. The method of extracting the position (coordinates) of one of the left and right corners in the main scanning direction in FIG. 7, for example, the left corner (point A), is the same as in the first embodiment.

Next, based on the left corner (point A), the main scanning width w
X The projection histogram in the main scanning direction is calculated for each block having the size of the sub-scanning width h, and the size of the main scanning width w is a fixed value as in the first and second embodiments. Instead, if the pattern (graphic) or character of the printed matter P is known in advance, as shown in FIG. 17, the main scanning width storage unit 407 determines the width of the pattern (graphic) or character in the main scanning direction. In addition, the main scanning width of each block is changed, and each block is calculated. The reason for changing the main scanning width of a block in this way is that when the main scanning width w is adjusted to the width of a pattern (figure) or character, the calculated histogram has a simple shape (the number of pixels in the main scanning direction is w or 0). This is because the processing speed is improved.

The projection histogram calculation unit 405 calculates a projection histogram in the main scanning direction for each block obtained by the variable block calculation unit 404. Here, similarly to the first embodiment, the main scanning width w of the block is determined by the number of pixels between the rectangular patterns in the sub scanning direction and the maximum rotation angle of the printed matter P. For example, if the number of pixels in the sub-scanning direction of the region to be extracted, that is, the number of pixels in the sub-scanning direction between rectangular patterns is c and the maximum rotation angle of the printed matter P is θ, the main scanning width w of the block is: w = c / Tanθ. The sub-scanning width h of the block is the vertical width of the image data.

In the region extraction unit 406, the projection histogram in the main scanning direction for each block obtained by the projection histogram calculation unit 405 is used, as in the first embodiment, so that the cumulative number of black pixels is “0”. An area, that is, a white area is extracted. When the cumulative black pixel is equal to or less than (w-1), the projection histogram in the sub-scanning direction is calculated in the area. From this projection histogram, an area where the accumulated black pixels are “0”, that is, a white area is extracted as described above.

Further, since the image data sometimes includes noise as shown in FIG. 12, for example, the cumulative number of black pixels is not set to “0” but is set to, for example, an area of “1” or less or “2” or less. By extracting the region as a white region, it is possible to accurately extract the region to be extracted. Here, the reason why the white area is extracted using the projection histogram in the sub-scanning direction as described above when the cumulative black pixel is equal to or less than (w-1) is the same as in the first embodiment.

Next, a fourth embodiment of the present invention will be described. FIG. 18 is a block diagram of an area extracting method according to the fourth embodiment of the present invention. The image input unit 501, the AD conversion unit 502, and the binarization processing unit 503 are the same as the image input unit 101, the AD conversion unit 102, and the binarization processing unit 103 in the first embodiment. A block having a specific main scanning width is calculated by the block calculating unit 504, and the calculated block and the main scanning of the pattern (figure) or character of the printed matter P stored in the main scanning width storage unit 507 are performed. Based on the information on the width, the variable projection histogram calculation unit 505 calculates the projection histogram in the main scanning direction and the sub-scanning direction for each block. Further, the area extracting unit 506 extracts an area other than a pattern (figure) or a character using the projection histogram.

A specific processing method of the block calculation unit 504, the variable projection histogram calculation unit 505, the area extraction unit 506, and the main scanning width storage unit 507 will be described below. The block calculator 504 extracts the left corner of the printed matter P, and calculates a block having a specific main scanning width from the left corner. Each block calculated by the block calculator 504 based on the information of the main scan width of the pattern (graphic) or the character of the printed matter P stored in the main scan width storage unit 507.
The main scanning width is further divided in the main scanning direction, and a projection in the main scanning direction is calculated for each of the divided blocks. Next, a white area is extracted from the calculated projection histogram,
Further, a white area is extracted from an area where a black area and a white area are mixed using a vertical projection histogram. As described above, a region to be extracted is extracted using a projection process for each block obtained by further dividing a specific main scanning width according to the main scanning width of a pattern (graphic) or character of the printed matter P.

The processing in the block calculator 504 will be described below. Left or right corner in the main scanning direction in FIG. 7,
For example, the method of extracting the position (coordinates) of the left corner (point A) is the same as in the first embodiment.

Next, based on the left corner (point A), the main scanning width w
X A block having a size of the sub-scanning width h is calculated. The variable projection histogram calculation unit 505 includes a block calculation unit 504
A projection histogram in the main scanning direction is calculated for each block obtained by the above. The size of the main scanning width w is a fixed value as in the first and second embodiments.
When the pattern (graphics) and characters of the printed matter P are known in advance, based on the information of the main scanning width of the printed matter P (graphics) and characters recorded in the main scanning width storage unit 507, The block is calculated in accordance with the width of the pattern (figure) or character and the main scanning width. Further, the variable projection histogram calculation unit 505
The main scanning width w of the block is subdivided, and a projection histogram in the main scanning direction is calculated for each of the divided blocks. That is, in FIG. 19, the width of the third block T from the left is w, but, for example, the main scanning width w is divided into w / 2 and w / 2 blocks in accordance with the pattern in this block. The projection histogram in each of the main scanning directions is calculated.

Here, as in the first embodiment, the main scanning width w of the block is determined by the number of pixels between the rectangular patterns in the sub scanning direction and the maximum rotation angle of the printed matter P. For example, if the number of pixels in the sub-scanning direction of the region to be extracted, that is, the number of pixels in the sub-scanning direction between rectangular patterns is c and the maximum rotation angle of the printed matter P is θ, the main scanning width w of the block is: w = c / Tanθ. The sub-scanning width h of the block is the sub-scanning width of the image data.

The region extraction unit 506 calculates the cumulative black from the projection histogram in the main scanning direction for each block (including the subdivided block) obtained by the variable projection histogram calculation unit 505 in the same manner as in the first embodiment. The number of pixels is
An area of “0”, that is, a white area is extracted. When the cumulative black pixel is equal to or less than (w-1), the projection histogram in the sub-scanning direction is calculated in the area. From this projection histogram, an area where the accumulated black pixels are “0”, that is, a white area is extracted as described above.

Further, since the image data sometimes includes noise as shown in FIG. 12, for example, the cumulative number of black pixels is not set to "0" but is set to an area of "1" or less or "2" or less. By extracting the region as a white region, it is possible to accurately extract the region to be extracted. Here, the reason why the white area is extracted using the projection histogram in the sub-scanning direction as described above when the cumulative black pixel is equal to or less than (w-1) is the same as in the first embodiment. In addition,
The present invention is not limited to the above-described embodiment, and it is needless to say that various modifications can be made without departing from the spirit of the invention.

[0048]

As described above, according to the present invention, horizontal and vertical projection processing is performed for each block divided in the vertical direction with reference to a dark pattern area such as a rectangular pattern of the printed matter P. By extracting the area of the printed matter P that is desired to be extracted, it is possible to reduce the influence of unevenness of conveyance, inclination, and lateral displacement of the printed matter P, and extract only the distance from the upper, lower, left, and right edges of the printed matter P. The extraction can be performed with higher accuracy than a conventional method of extracting a region to be processed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an area extraction system according to a first embodiment of the present invention.

FIG. 2 is a flowchart showing a processing method in an area extracting unit according to the first embodiment of the present invention.

FIG. 3 is a diagram illustrating a configuration of an image input unit in FIG. 1;

FIG. 4 is a diagram illustrating an example of a print image.

FIG. 5 is a diagram illustrating a configuration of a background of a printed matter in an image input unit.

FIG. 6 is a diagram illustrating an example of an area extracted from a printed matter;

FIG. 7 is a diagram showing a left corner of a printed matter on image data.

FIG. 8 is a diagram illustrating a method of searching for a left corner of a printed matter from image data.

FIG. 9 is a diagram for explaining a process of calculating a horizontal projection histogram from image data.

FIG. 10 is a diagram showing an example of a horizontal projection histogram of a certain block;

FIG. 11 is a diagram showing an example of a vertical projection histogram in a certain block.

FIG. 12 is a diagram showing noise on image data.

FIG. 13 is a view for explaining processing for calculating a vertical projection histogram on image data.

FIG. 14 is a block diagram showing a configuration of an area extraction system according to a second embodiment of the present invention.

FIG. 15 is a diagram for explaining a process of calculating a horizontal projection histogram according to the second embodiment of the present invention.

FIG. 16 is a block diagram showing a configuration of an area extraction system according to a third embodiment of the present invention.

FIG. 17 is a diagram for explaining processing for calculating a horizontal projection histogram according to the third embodiment of the present invention.

FIG. 18 is a block diagram showing a configuration of an area extraction system according to a fourth embodiment of the present invention.

FIG. 19 is a view for explaining processing for calculating a horizontal projection histogram according to the fourth embodiment of the present invention.

Claims (7)

[Claims] 1. A method for extracting a specific area of a target printed matter, comprising: an image inputting step of inputting image data of the printed matter; and
A block calculation step of calculating a plurality of blocks having a specific main scanning width; a projection histogram calculation step of calculating a projection histogram in the main scanning direction for each block obtained from the block calculation step; and the projection histogram calculation step An area extracting step of extracting the specific area using the projection histogram obtained as described above. 2. A method for extracting a specific region of a target printed matter, comprising: an image inputting step of inputting image data of the printed matter; and
An overlap block calculation step of calculating a block having a specific main scanning width so as to overlap each block; and a projection calculating a projection histogram in the main scanning direction for each block obtained from the overlap block calculation step. A region extraction method characterized by comprising: a histogram calculation step; and a region extraction step of extracting the specific region using the projection histogram obtained from the projection histogram calculation step. 3. A method for extracting a specific area of a target printed matter, comprising: an image inputting step of inputting image data of the printed matter; and a main scanning width storing a main scanning width of a known pattern as a dictionary. Step, based on the image data obtained in the image input step,
A variable block calculating step of calculating a block corresponding to a main scanning width of a pattern known in advance by the main scanning width storage step; and calculating a projection histogram in the main scanning direction for each block obtained from the variable block calculating step. A region extraction method for extracting the specific region using the projection histogram obtained from the projection histogram calculation step. 4. A method for extracting a specific area of a target printed matter, comprising: an image inputting step of inputting image data of the printed matter; and
A block calculating step of calculating a block having a specific main scanning width; a main scanning width storing step of registering a main scanning width of a known pattern as a dictionary; and a main scanning width storing step. For a specific block, a projection histogram in the main scanning direction is calculated for each block obtained in the block calculation step, and in another block, the block obtained in the block calculation step is replaced with a pattern existing in the block. A projection histogram calculating step of subdividing into blocks corresponding to the main scanning width and calculating a projection histogram in the main scanning direction; and an area extracting step of extracting the specific area using the projection histogram obtained from the projection histogram calculating step And a region extracting method. 5. The block calculation step according to claim 1, wherein the block calculation step includes a binarization step of binarizing the image data obtained in the image input step to distinguish black pixels and white pixels. 2. The region extraction method according to claim 1. 6. The projection histogram calculating step further includes a sub-scanning direction projection histogram calculating step of calculating a projection histogram in the sub-scanning direction for an area where white pixels and black pixels coexist. The method according to claim 5, further comprising the step of extracting the specific area using a projection histogram of directions. 7. The region extracting step includes, for a region where white pixels and black pixels are mixed in the projection histogram,
6. The method according to claim 5, further comprising the step of extracting, as the specific area, an area in which the number of black pixels is equal to or less than a predetermined value.