JP2000156762A - Image processor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image processor that can discriminate whether or not a read original is white paper with higher accuracy. SOLUTION: In this image processor that processes image data read from and original, an A/D converter provided in a scanner section 1 converts an analog image signal into multi-value digital pixel data, a white paper detection section 2 compares the pixel at a with a prescribed density value and discriminates a page to be white paper, when all of the pixel data in the page are the density value or below. Furthermore, a counter that counts the number of the pixel data, whose density exceeds the prescribed density is provide in the white paper detection section 2 and when number of the pixel data in one page counted by the counter is a prescribed number or below, the white paper detection section 2 discriminates the page to be a white paper.

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 such as a facsimile apparatus, a copying machine, and an image reading apparatus, and more particularly to an image processing apparatus capable of determining whether a read page is a blank page.

[0002]

2. Description of the Related Art In recent years, a large-capacity semiconductor memory can be obtained at low cost. For example, various image processing and processing based on data stored in a semiconductor memory can be performed in a facsimile apparatus, a copying machine, and the like. became. For example, based on the data stored in the semiconductor memory, determine whether the page read from the document is blank, if it is blank, notify the user to that effect, do not send a blank page facsimile, Alternatively, it is possible to not copy a blank page. As a specific example of the above, in a facsimile apparatus disclosed in Japanese Patent Application Laid-Open No. 63-14566, it is determined whether or not a blank sheet has been sent by counting a change point of an image signal by a decoding device on the receiving side. However, it is described that when a blank sheet is sent, the transmitting side is notified of the fact, and that the operator is notified that the blank side of the document has been read due to an operation error.

[0003]

However, in the above-described prior art, the presence or absence of a black image is determined based on black and white binary image data. There is a problem that image data of intermediate density such as dust and noise is also erroneously determined as a black image. It is an object of the present invention to solve the above-described problems of the related art and to provide an image processing apparatus capable of more accurately determining whether or not a sheet is blank.

[0004]

According to a first aspect of the present invention, in an image processing apparatus for processing image data read from a document, an analog image signal is converted to a multi-valued digital pixel. AD to convert to data
A converting unit; and a blank sheet detecting unit that determines that the page is blank when all of the pixel data of the read page is equal to or less than a predetermined density. Further, in the invention according to claim 2, in the above, the image processing apparatus further includes a background detection unit that detects a background density of the document, and the blank page detection unit determines the density of the pixel data based on the background density. According to a third aspect of the present invention, the image processing apparatus further includes a data number counting means for counting the number of pixel data in one page in which the density of the pixel data exceeds the predetermined density. When the number of pixel data counted by the means is equal to or smaller than a predetermined value, it is determined that the sheet is blank. Further, in the invention according to claim 4, in the above, when the image processing device includes a transmission processing unit that can transmit the pixel data, after the determination by the blank sheet detection unit is performed, each pixel data is The transmission processing is performed by binarization.

According to the first aspect of the present invention, when all the pixel data of a read page is lower than a predetermined density, the page is determined to be blank.
According to a second aspect of the present invention, in the first aspect, the predetermined density is determined based on a background density. In the invention according to claim 3, claim 1 or claim 2
In the invention described above, the page is determined to be blank when the number of pixel data exceeding a predetermined density is equal to or smaller than a predetermined value. According to a fourth aspect of the present invention, in the first, second or third aspect of the present invention, each pixel data is binarized and transmitted after the determination by the blank page detecting means is performed.

[0006]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a configuration block diagram of a main part of an image processing apparatus according to a first embodiment of the present invention. As shown in the figure, the image processing apparatus according to the present embodiment includes a scanner unit 1 that reads multi-valued image data corresponding to a density from a document, and determines whether the read multi-valued image data of each pixel is smaller than a predetermined density. And a storage section 3 for storing various data such as image data, a control section 4 for controlling the entire image processing apparatus, and the like. The scanner unit 1 includes a photoelectric conversion device and an A / D conversion device (AD conversion unit), and the blank sheet detection unit 2 includes a logic circuit and the like. FIG. 2 shows an operation flow of the first embodiment. Hereinafter, the operation of the present embodiment will be described with reference to FIG. Note that, as shown in FIG. 2, all processes except for step S1 are performed by the blank page detecting unit 2.
Executed in As shown in FIG. 2, first, an image is read from a document by the scanner unit 1 (S1). The density of each pixel on the document is input to the photoelectric conversion unit of the scanner unit 1 as a light amount, an analog electric signal corresponding to the light amount is output from the photoelectric conversion device, and a multi-valued digital image is output by the A / D conversion device. It is converted into data (pixel data). Subsequently, the image data of each pixel is passed to the blank sheet detecting section 2 and is compared with a predetermined density value by a comparison circuit in the inside (S2). The density value is set in a register in the blank sheet detection unit 2 by the control unit 4 in advance.

[0007] This is the case when the output value of the comparison circuit indicates that the image data (pixel data) of the pixel (pixel of interest) is smaller than the density value (Yes in S2) and the next page in the same page. If the image data of a pixel has been input and the density comparison of all pixels has not been completed (No in S3), the same density comparison as described above is performed for the next pixel (S3).
2). If it is determined that the image data of all the pixels in the same page is smaller than the density value (Ye in S3)
In s), the blank page detection unit 2 determines that the page is blank (S4). On the other hand, when the output value of the comparison circuit indicates that the image data of the pixel (target pixel) is equal to or higher than the density value before the density comparison of the image data of the last pixel of the same page is performed. (No in S2), it is determined that the page is not blank at that time (S2).
5). In this manner, according to the present embodiment, the predetermined density is set to be slightly larger than the intermediate density image data such as show-through of the document, dust on the document and the reading surface, noise, etc. For example, even if there is show-through, etc. even though it is a blank sheet, the density of the show-through part is lower than a predetermined density and it is determined to be white, so that the part is regarded as black and not a blank sheet as in the related art No misjudgment is made. In the above embodiment, the blank page detection unit 2 has been described as being configured with a logic circuit or the like, but may be configured with a CPU or the like.
The PU may be the same as the CPU in the control unit 4.

FIG. 3 is a block diagram showing the configuration of a main part of an image processing apparatus according to a second embodiment of the present invention. As shown in the figure, the image processing apparatus of the present embodiment is obtained by adding a background detection unit (background detection means) 5 to the configuration of the first embodiment shown in FIG. Hereinafter, the operation of the present embodiment will be described according to the operation flow shown in FIG. First, an image is read from a document by the scanner unit 1 (S11), and the multi-value digitized image data is stored in the storage unit 3 and given to the background detection unit 5. Based on the image data, the background detection unit 5 detects the density of the background portion (S12). In the density detection of the background portion, for example, image data of a predetermined value or less is regarded as image data of the background portion, and the average value is set as the background density. Note that this average value does not need to be the average value of the entire page, and may be, for example, the average value of the first part of the page, which corresponds to about a quarter of the entire page. When the background density is determined, the background detection unit 5 gives the value to the control unit 4, and based on the value, the control unit 4 determines a larger value as the background density J is larger as shown in the following equation, for example. Is set in a register in the blank sheet detection unit 2 as the density value K. K = J + α (α: constant) Then, the control unit 4 sequentially reads out the image data once stored in the storage unit 3 from the head thereof, passes the image data of each pixel to the blank page detection unit 2, The internal comparison circuit compares with the density value set in the register (S1
3). This is the case when the output value of the comparison circuit indicates that the image data of the pixel (target pixel) is smaller than the density value (Yes in S13), and the image data of the next pixel in the same page is input. If it is (No in S14),
A density comparison similar to the above is performed for the next pixel (S1
3). If it is determined that the image data of all the pixels in the same page is smaller than the density value (Ye in S14)
In s), the blank page detection unit 2 determines that the page is blank (S15). On the other hand, when the output value of the comparison circuit indicates that the image data of the pixel (target pixel) is equal to or higher than the density value before the density comparison of the image data of the last pixel on the same page is performed (S13). No), it is determined that the page is not blank at that time (S16). In this way, according to the present embodiment, it is possible to eliminate a case where a black background is erroneously determined to be not a blank sheet than a show-through on a white background, for example. In the first and second embodiments, if at least one piece of image data (pixel) having a predetermined density or more is detected, it is determined that the image is not a blank page. In the embodiment, when image data having a predetermined density or more is detected to be a predetermined value or more, it is determined that the image is not blank. FIG. 5 shows an operation flow of the third embodiment. The hardware configuration is the same as that of the first embodiment shown in FIG. Hereinafter, the operation of the present embodiment will be described with reference to FIG.

First, the scanner unit 1 reads an image from a document (S21), passes the digitized image data of each pixel to the blank page detection unit 2, and sequentially converts the image data of each pixel by the internal comparison circuit. Compare with a predetermined density value. Then, the number of times that the image data having the predetermined density or more is detected by the counter in the blank sheet detecting section 2 is counted (S2).
2) If the value of the counter does not reach the predetermined value (predetermined number of times) by the end of the page (Yes in S23), the blank page detection unit 2 determines that the page is blank (S24). On the other hand, when the value of the counter reaches the predetermined number of times before the density comparison of the image data of the last pixel of the same page is performed (No in S23), it is determined that the page is not blank at that time (S25). ). In this manner, according to the present embodiment, not only the same effect as in the first embodiment is obtained, but also a page that is originally a blank page is erroneously determined to be not a blank page due to high density dust and noise. Can be avoided. In the fourth embodiment of the present invention, when the predetermined density is determined based on the background density,
When image data having a predetermined density or more is detected a predetermined number of times or more, it is determined that the image is not blank. FIG.
3 shows an operation flow of the embodiment. The hardware configuration is the same as that of the second embodiment shown in FIG. Less than,
The operation of this embodiment will be described with reference to FIG.

First, the scanner unit 1 reads an image from a document (S31), and the background detection unit 5 detects the background density (see S12 of the second embodiment) (S32).
Calculates a predetermined density value based on the background density
, And digitized image data of each pixel is transferred to the blank page detection unit 2, and the image data of each pixel is sequentially compared with a predetermined density value by an internal comparison circuit. Then, the number of times that the image data having the predetermined density or more is detected by the counter in the blank sheet detecting section 2 is counted (S3).
3) If the value of the counter does not reach the predetermined value (predetermined number of times) before the end of the page (Yes in S34), the blank page detection unit 2 determines that the page is blank (S35). On the other hand, when the value of the counter reaches the predetermined number of times before the density comparison of the image data of the last pixel of the same page is performed (No in S34), it is determined that the page is not blank at that time. (S36). In this manner, according to the present embodiment, not only the same effect as in the second embodiment is obtained, but also a page which is originally a blank page is erroneously determined to be not a blank page due to high density dust and noise. Can be avoided. In the case where the image processing apparatus includes a transmission processing unit such as a facsimile apparatus, in the above-described embodiment, after the determination by the blank sheet detection unit is performed, each multi-valued pixel data is binarized. It is sent from the subsequent transmission processing unit.

[0011]

As described above, according to the present invention,
According to the first aspect of the present invention, when all pixel data of a read page is equal to or less than a predetermined density, the page is determined to be a blank page. For example, by setting the data slightly larger than the image data of the intermediate density, it is possible to eliminate a situation in which the data is erroneously determined as a black image. According to the second aspect of the present invention, in the first aspect, the predetermined density is determined based on the background density. For example, when the density of show-through is smaller than the background density, the background density is determined. It is not necessary to erroneously determine a show-through or the like as a black image in a case where the image is small, and it is possible to eliminate a situation in which a background having a high density is erroneously determined as a black image. According to the third aspect of the present invention, in the first aspect or the second aspect,
In the invention described in the above, the page is determined to be blank when the number of pixel data exceeding a predetermined density on the page is equal to or less than a predetermined value. Regarding as a black image,
It is possible to eliminate a situation in which an erroneous judgment is made that the sheet is not blank.
According to the fourth aspect of the present invention, in the first, second or third aspect of the present invention, each pixel data is binarized after the determination by the blank sheet detecting means. In the case where the processing device is a facsimile device including a transmission processing unit, the pixel data can be converted into binary image data used for facsimile communication and transmitted.

[Brief description of the drawings]

FIG. 1 is a configuration block diagram of a main part of an image processing apparatus according to a first embodiment of the present invention.

FIG. 2 is an operation flowchart of a main part of the image processing apparatus according to the first embodiment of the present invention.

FIG. 3 is a configuration block diagram of a main part of an image processing apparatus according to a second embodiment of the present invention.

FIG. 4 is an operation flowchart of a main part of an image processing apparatus according to a second embodiment of the present invention.

FIG. 5 is an operation flowchart of a main part of an image processing apparatus according to a third embodiment of the present invention.

FIG. 6 is an operation flowchart of a main part of an image processing apparatus according to a fourth embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Scanner part, 2 ... Blank paper detection part, 3 ... Storage part, 4 ... Control part, 5 ... Background detection part,

Claims (4)

[Claims] 1. An image processing apparatus for processing image data read from a document, comprising: an A / D converter for converting an analog image signal into multi-valued digital pixel data; An image processing apparatus comprising: a blank page detection unit that determines that the page is a blank page when the density is equal to or less than the density. 2. The image processing apparatus according to claim 1, further comprising a background detection unit for detecting a background density of the document, wherein the blank page detection unit determines the density of the pixel data based on the background density. An image processing apparatus characterized by the above-mentioned. 3. The image processing apparatus according to claim 1, further comprising: data number counting means for counting the number of pixel data in one page in which the density of the pixel data exceeds the predetermined density; The image processing apparatus is characterized in that when the number of pixel data counted by the data counting means is equal to or smaller than a predetermined value, it is determined that the sheet is blank. 4. The image processing apparatus according to claim 1, wherein the image processing apparatus includes a transmission processing unit capable of transmitting the pixel data, wherein the determination by the blank sheet detection unit is performed. An image processing apparatus, characterized in that, after being executed, each pixel data is binarized and transmission processing is executed.