JP4759181B2 - Image reading method, apparatus, program, and medium storing program - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image reading apparatus and a control method thereof, and more particularly to an image reading apparatus that extracts and reads a document area.
[0002]
[Prior art]
An image reading apparatus is shown in FIG. In FIG. 1, 101 is a document table cover for pressing a set document, the surface on the document side is white, 102 is a document table for placing a document, 103 is a document reading unit for reading a set document, 104 is A document alignment mark to be aligned when setting the document is shown. A document is placed on the document table 102, and the document is read by a document reading unit 103 including a document illumination LED, a photoelectric conversion element array, a lens for forming a document image on the photoelectric conversion element array, and the like. Although not shown, the image reading apparatus further includes a motor that drives the document reading unit in the sub-scanning direction, and a signal processing circuit board that processes image signals read by the photoelectric conversion element array, and is connected to the host computer with a USB cable. Has been.
[0003]
FIG. 5 shows a document area cutout process. Conventional processing will be described. First, in step S501, a document is placed on the document table, the entire surface of the document table is read, and an RGB color image of the entire surface of the document table is acquired. In step S502, this image is converted into a monochrome binary image. Here, each pixel value is converted to white if the value of G is greater than a certain threshold, and if it is greater than that, or black if it is less than the threshold, to create a monochrome binary image. Here, the threshold for creating a monochrome binary image will be described. This threshold is a value for determining whether or not there is a document. Therefore, if an image is read without placing the document on the platen, the white part on the back of the platen is read. The value of this part is 24bit color and the pixel values of R, G, B are all 255 (0xFF). It has become. Therefore, this threshold is set to a value close to 255 (0xFF), and the presence / absence of a document is determined. In step S503, this black and white binary image is input to the program of the area cutout module. The area cutout module outputs information on the number of sheets, the position, and the size of the original document using the monochrome image. The result of area extraction will be described with reference to FIG. As shown in FIG. 6A, when the originals A601 and B602 are placed on the original platen 102, a black and white binary image of the entire surface of the original platen is created and input to the area cutout module. Thus, a correct crop area can be acquired for the originals A601 and B602.
[0004]
If the image data of the crop area acquired in step S503 is cut out from the color image of the entire surface of the document table acquired in step S501, the image data of the document area can be acquired.
[0005]
Here, when a color image on the entire surface of the document table is converted into a black and white binary image, light leaks from a slight gap between the document table 102 of the scanner and the document table cover 101, so that the monochrome image is not read by the reading unit. When an image is created, light leakage appears as black streaks 605 at the upper and left edges of the image. For this reason, if a black and white binary image in which black streaks 605 appear is input to the area cutout module, it may be erroneously detected when detecting the number, position, and size of the image. The situation at this time is shown in FIGS. If there are black streaks 605 caused by light leakage in addition to the originals A601 and B602 placed on the original table 102, an incorrect crop area is acquired as shown in FIG. Further, when cropping to the area for each original, the black streak and the original A may be recognized as one original as shown in FIG.
[0006]
[Problems to be solved by the invention]
In the image reading apparatus as described above, when automatic document area identification is performed, an unnecessary image is generated at the edge of the document area, and the document area may not be accurately identified.
[0007]
The present invention has been made in view of the above problems, and when an image area is automatically identified by an image reading apparatus, erroneous identification of an original area due to an unnecessary image is prevented, and an image of the original area is accurately obtained. For the purpose.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the present invention is configured as follows.
[0009]
An image reading method for reading an image of a sheet- like document placed in a rectangular reading range between a white document table cover and a transparent document table , wherein the vertex of the document alignment with the rectangular document table is 1 a step of the reading range entirely get read entire image data One of shares as the vertex is smaller rectangle than the document cover, the strip-shaped edge of the image of the two sides forming the vertices of all faces the image data of the rectangular and muscle image detection step for detecting the presence or absence of the document or image other than the document cover in the region, the image data other than the document or the document cover, which is detected by the muscle image detection process by replacing the white data to and muscle image deletion step of deleting from the previous SL entire surface image data from the image data obtained by the muscle image deletion process, characterized in that it has an identification step of identifying the rectangular document area Image reading method.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.
[0022]
The embodiment of the present invention is implemented by a system in which an image reading apparatus and a computer are connected as described in FIG. 1, and an image read by the image reading apparatus and converted into a digital image signal is processed by the computer. Is done.
[0023]
FIG. 2 is a monochrome binary image created from an image obtained by scanning the entire surface of the document table. (It is assumed that the black and white binary image is read at 75 dpi) As shown in FIG. 2, processing ranges 201 and 202 are provided at the upper and left ends of the black and white binary image, and there are black streaks in this processing range. Judgment is made. The processing range is a full width in the main scanning direction of the upper end portion of the black and white binary image, a range 201 corresponding to 16 lines in the sub scanning direction, a width corresponding to 16 pixels in the main scanning direction in the left end portion, and a full height range 202 in the sub scanning direction. Here, no processing is performed on the right end or lower end portion of the black and white binary image, because the right end and lower end portions are not the portions corresponding to the edges of the platen, and the outside is the portion still covered by the platen cover 101. This is because it is difficult to be affected by light leaking from the document tables 102 and 204 and the document table cover 101. The process of removing the black streak is performed as a pre-process of step S503 of the conventional technique described with reference to FIG.
[0024]
First, the processing of the left end portion of the black and white binary image will be described. FIG. 3 is a flowchart showing the processing at the left end. In step S301, the entire surface of the document table is read in color, and a 24-bit color image of the entire surface of the document table is acquired. In step S302, a black and white binary image is created from the 24-bit color image of the entire surface of the original plate acquired in step S301. The monochrome binary image is 0 when each pixel value is white and 1 when the pixel value is black. In step S303, a search is performed for the first line in the main scanning direction. In step S304, a search is performed for a width of 16 pixels from the left end of the upper first line of the black and white binary image. (See 202 in FIG. 2) With reference to the pixel values of 13 to 16 pixels in the width of 16 pixels from the left end, it is determined whether or not the pixel values of 13 to 16 pixels are all white (0). In step S305, when the determination in step S304 is Yes, it is determined that there is no document on this line, and all the values of the width of 16 pixels from the left end are replaced with white (0). In step S306, it is determined which line in the main scanning direction is being processed. If the current number of lines does not reach the final line in the main scanning direction of the monochrome binary image, the process moves to the next line (step S308), and the process of step S304 is performed. In step S307, when the determination in step S304 is No, the process moves to the next line and the process of step S304 is performed.
[0025]
Next, processing of the upper end portion of the monochrome binary image will be described. FIG. 4 is a flowchart showing processing of the upper end portion. In step S401, the entire surface of the document table is read in color, and a 24-bit color image of the entire surface of the document table is acquired. In step S402, a monochrome binary image is created from the 24-bit color image of the entire surface of the original plate acquired in step S401. The monochrome binary image is 0 when each pixel value is white and 1 when the pixel value is black. In step S403, a search is performed for the first line in the sub-scanning direction. In step S404, a search is performed for a width of 16 pixels from the upper end of the first line on the left end of the monochrome binary image. (See FIG. 2 201) With reference to the pixel values of 13 to 16 pixels in the width of 16 pixels from the upper end, it is determined whether the pixel values of 13 to 16 pixels are all white (0). In step S405, when the determination in step S404 is Yes, it is determined that there is no document in this line, and all the values of the width of 16 pixels from the upper end are replaced with white (0). In step S406, it is determined which line in the sub-scanning direction is being processed. If the current number of lines does not reach the final number of lines in the sub-scanning direction of the black and white binary image, the process moves to the next line (step S408), and the process of step S404 is performed. In step S407, when the determination in step S404 is No, the process moves to the next line and the process of step S404 is performed.
[0026]
When these left and top edge processing is performed on a black and white binary image, it is possible to remove black streaks caused by light leaking from a slight gap between the scanner platen 102 and the platen cover 101. The area cutout described in step S503 in FIG. 5 is performed on the black and white binary image subjected to these processes. If the image data of the document area determined by the area extraction module program is extracted from the 24-bit color image data of the entire surface of the document plate acquired in step S301 or S401, the image data of the document area can be obtained. Image data corresponding to each original can be acquired from a plurality of originals.
[0027]
In the description of FIG. 3 and FIG. 4 above, the 24-bit color image of the entire surface of the document table is acquired and converted to black and white, but binary data can also be used in common.
[0028]
Also, depending on the positional relationship between the document table cover and the platen glass, the black streaks are not always located at the left and top edges. Carry out to remove.
[0029]
In the above description, the system of the image reading apparatus and the host computer as shown in FIG. 1 is used. However, the present invention is not limited to this and can be applied to an integrated reading apparatus.
[0030]
【The invention's effect】
According to the present invention, it is possible to prevent erroneous determination when automatically determining a document area, and to accurately obtain an image of the document area.
[Brief description of the drawings]
FIG. 1 is a diagram showing a scanner main body and components.
FIG. 2 is a diagram showing a region of a black and white binary image to which the present invention is applied.
FIG. 3 is a flowchart illustrating black streak removal processing at the left end according to the embodiment.
FIG. 4 is a flowchart showing black streak removal processing at the upper end of the embodiment.
FIG. 5 is a flowchart showing a conventional document region extraction process;
FIG. 6 is a diagram for explaining region cut-out processing;

Claims (10)

An image reading method for reading an image of a sheet- like document placed in a rectangular reading range between a white document table cover and a transparent document table,
A step of sharing the vertex of the original plate with the rectangular original plate as one vertex and reading the entire reading range which is a rectangle smaller than the original plate cover to obtain full image data;
And muscle image detection step for detecting the presence or absence of the document or the document cover other images in a strip area of the image edge portion of the two sides forming the vertices of all faces the image data of the rectangular,
And muscle image deletion step of deleting from the previous SL entire surface image data by replacing the white data detected image data other than the document or the document cover has been in the muscle image detection step,
An image reading method comprising: an identification step of identifying a rectangular document region from image data obtained in the stripe image deletion step.   The image reading method according to claim 1 further includes a step of obtaining an image data of the document area by cutting out the image of the rectangular document area identified in the identifying step from the entire surface image data.   The image reading method according to claim 1 includes a step of binarizing the read entire surface image data, and performing the stripe image detecting step on the binarized front image data.   The image reading method according to claim 1, wherein the identifying step is a step of individually identifying a plurality of document regions arranged on the document table. An image reading apparatus for reading an image of a sheet document placed in a rectangular reading range between a white document table cover and a transparent document table,
An image reading unit that shares the vertex of the rectangular document table and the document alignment as one vertex , reads the entire reading range that is a rectangle smaller than the document table cover, and obtains entire image data;
And muscle image detection means for detecting the presence or absence of the document or the document cover other images in a strip area of the image edge portion of the two sides forming the vertices of all faces the image data of the rectangular read by said image reading means ,
And muscle image deletion means for deleting from the front image data detected image data other than the document or the document cover has been by replacing white data in the muscle image detection means,
An image reading apparatus comprising: identification means for identifying a rectangular document region from image data obtained by the stripe image deletion means. According to a fifth aspect of the present invention , the image reading apparatus further includes means for cutting out an image of the rectangular document area identified by the identifying means from the entire image data to obtain image data of the document area. According to a fifth aspect of the present invention , the image reading apparatus includes image binarizing means for binarizing the read entire surface image data, and detects the stripe image from the binarized front image data. 6. The image reading apparatus according to claim 5 , wherein the identification unit is a unit for individually identifying a plurality of document areas arranged on the document table. A computer-executable program for realizing the image reading method according to any one of claims 1 to 4 in an image reading apparatus and a computer. A recording medium in which the program according to claim 9 is described.

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