JPH05336316A - Image input/output device - Google Patents

Abstract

PURPOSE:To obtain an image input/output device capable of accurately discriminating between an original and an original detection plate and detecting the size of the original faithfully to the original, even when a color which is close to a reference value exists in the original. CONSTITUTION:This image input/output device is composed of an original detection plate 2 for pressing down an original and discriminating from the original, a reading means 3 reading the original 1 and the original detection plate 2, a discriminating means 4 comparing the image data read from the reading means 3 and reference data and discriminating between the original 1 and the original detection plate 2, an original area correction means 5 correcting the discrimination result by the discriminating means 4 and a detecting means 14 detecting the original area from the original area correction means 5.

Description

Detailed Description of the Invention

[0001]

This invention relates to an image scanner,
The present invention relates to an image input / output device such as a copying machine, and particularly to an image input / output device having a function of automatically detecting an area of a document to be read.

[0002]

2. Description of the Related Art Conventionally, in a method of detecting the size of a document in an image input / output device, a reference value for reading a document detection plate for pressing the document is prepared in advance, and the reference value and the light source are set. The size of the document is detected by comparing the image data obtained by color separation such as switching or switching the filter in pixel units. For example, if the reference value and the image data value are equal, it is determined that the document area is not the original area, and if they are not equal, the original area is determined.

FIG. 9 is a block diagram showing a conventional example. Reference numeral 1 is a document, 2 is a document detecting plate, 3 is a reading unit, 4 is a discriminating unit, and 14 is a detecting unit. The original detection plate 2 covers the entire readable area of the image reading means 3 and fixes the original 1 to the reading means 4.

The reading means 3 comprises a document table on which the document 1 is placed, a light source for irradiating the document 1, an image sensor for reading the reflected light irradiating the document 1, and the like. The document 1 is optically read and photoelectrically converted. Output. The discriminating means 4 is composed of a comparator and a flip-flop (hereinafter referred to as FF), and compares the reference data for discrimination with the image data 20 read by the reading means 3 to determine whether or not the original area is read. It is to determine. The identification result 21 is output to the detection means 14.

The detecting means 14 is composed of a counter and a register. Next, the operation of FIG. 9 will be described. Manuscript 1
Is placed on the document table of the reading means 3, and the document detection plate 2 is placed so as to cover the document 1. Next, the reading means 3 reads the document 1 placed on the document table and the document detection plate 2 covering the document 1,
The image data 20 is input to the discriminating means 4.

The operation of the discriminating means 4 will be described with reference to FIG. The image data 20 is synchronized with the clock 22 and is written in the FF 6 by the clock 22. The register 7 stores data serving as a reference for discrimination, that is, the reading unit 3.
Thus, a value equal to or close to the value read by the document detection plate 2 is stored. The comparator 8 compares the outputs of the FF 6 and the register 7 while the LENB signal 23 indicating the effective range of the image data 20 is active. For example, if the values of the data 24 and 25 are equal, the read position is the original detection plate 2. Identification result 2 indicating “0” indicating that there is
If the value is 1, and the values of 24 and 25 are different, "1" indicating that the read position is the original 1 is input to the detection means 14 as the identification result 21. The data stored in the register 7 is not limited to the data prepared in advance, and a value obtained by reading the original detection plate 2 before reading the original 1 may be stored.

In FIG. 7, the image data 20, the data 24, and 25 are represented by 1 bit for simplification, but in reality, these are represented by a plurality of bits, and therefore, the FF 6, the register 7, and the comparator 8 are constituted by a plurality of bits. Bits are aligned. The detection unit 14 detects the outline of the document or the rectangle circumscribing the document based on the identification result 21, and the operation of detecting the rectangle circumscribing the document will be described with reference to the flowchart of FIG.

In step 50, the maximum value register, the minimum value register, the counter and the like in both the main scanning direction and the sub scanning direction are initialized. Here, the minimum value that can actually occur is stored as XMAX in the maximum value register in the main scanning direction. The maximum value that can actually occur is stored as XMIX in the minimum value register in the main scanning direction.
Similarly, the minimum value that can actually occur is stored as YMAX in the maximum value register in the sub-scanning direction. Further, the maximum value that can actually occur is stored as YMIX in the minimum value register in the sub-scanning direction.

At step 51, it is judged whether or not the operation is completed based on the value of the counter for counting the LENB signal 23. In step 52, while the LENB signal 23 is enabled, the start and end of the pixels identified as the original are detected by the value of the counter that counts the clock 22. At this time, the first value is the minimum value and the last value is the maximum value.

In step 53, it is judged whether or not the pixel identified as the original exists, and if it exists, step 5 is executed.
4; if not present, proceed to step 51. In step 54, the maximum value is compared with the already set XMAX, and if the maximum value is larger than XMAX, step 55
If not, go to step 56.

In step 55, the maximum value is written in the maximum value register in the main scanning direction. In step 56, the minimum value is compared with the already set XMIX, and the minimum value is XMIX.
If it is smaller, the process proceeds to step 57, and if it is larger, the process proceeds to step 58. In step 57, the minimum value is written in the minimum value register in the main scanning direction.

In step 58, the position in the sub-scanning direction is detected by the value of the counter that counts the LENB signal 23.
In step 59, the count value obtained in step 58 and YMI
X is compared. If the count value is smaller than YMIX, the process proceeds to step 60, and if it is larger, the process proceeds to step 61.

In step 60, the count value is written in the minimum value register in the sub-scanning direction. In Step 61, Step 5
The count value obtained in step 8 is compared with YMAX, and the count value is YMA.
When it is larger than X, the process proceeds to step 62, and when it is smaller, the process proceeds to step 51. In step 62, the count value is written in the maximum value register in the sub-scanning direction.

By the above operation, the rectangle circumscribing the original is detected.

[0015]

However, in the conventional original area detection circuit, the size of the original is discriminated on a pixel-by-pixel basis based on a reference value prepared in advance. Therefore, when the data value fluctuates due to the influence of noise, When there is a color close to the reference value in the document, the reference value and the image data value become equal to each other even though the document is read, and it is determined that the plate is the document detection plate. Therefore, there is a problem that the original and the original detection plate cannot be accurately identified.

SUMMARY OF THE INVENTION An object of the present invention is to provide an image input / output device which can accurately distinguish a document from a document detection plate even if the document has a color close to the reference value.

[0017]

In order to solve the above problems, the present invention holds an original document in an image input / output device such as an image scanner for reading the original document and displaying it on a display or a copying machine for printing on an image receiving paper. An original detecting plate for distinguishing the original from the original, a reading unit for reading the original and the original detecting plate, and a discriminating unit for comparing the image data read by the reading unit with the reference data to identify the original and the original detecting plate. The document area correction means for correcting the identification result of the discrimination means.

[0018]

In the image input / output device configured as described above, the image data read by the conventional configuration is used to discriminate the original document from the original detection plate on a pixel-by-pixel basis, and further, all pixels within the determined area are identified. The original is discriminated from the original detection plate depending on how many pixels are judged to be the original or the original plate in the area.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of an embodiment of the present invention, and the configuration up to obtaining the identification signal 21 and its operation are as described above, and will be omitted here. The document area correction means 5 is composed of a memory, a counter, a comparator, and the like, and again identifies whether or not the identification result 21 is obtained by reading the original area by referring to the identification result 21 around the pixel currently undergoing the identification determination. Is.

Next, the operation of FIG. 1 will be described. The identification signal 21 output by the determination means 4 is input to the original area correction means 5 in order to identify the original area more accurately. Here, an example is used in which the reference area is 4 pixels including 2 pixels in both the main scanning direction and the sub-scanning direction, and when the identification reference is 2 pixels or more, the original detection plate is identified. And

FIG. 8 is a block diagram showing the construction of the original area correction means 5. The identification signal 21 is input to the line memory 9 and the 2 × 2 counting means 11 in synchronization with the clock 22. At this time, the memory control means 10 outputs the address 27 and the control signal 28 consisting of the read signal and the write signal at the timing shown in FIG. The clock 22 is counted while the LENB signal 23 is enabled, the count result is output as the address 27, and the address is reset in the disable state. As a result, the identification signal 29 and the identification signal 21 delayed by one line become 2 × 2 counting means 1
1, the identification signal 21 is stored in the line memory 9 as delay data of the next line.

The 2 × 2 counting means 11 has a buffer for delaying one pixel inside, and the data obtained by delaying the identification signal 21 and the identification signal 29 delayed by one line and the input data in the main scanning direction and the sub-scanning direction. The signals discriminated as the original detection plate are counted by 4 pixels each including 2 pixels in the direction, and the count result 30 is input to the comparator 13.
The comparator 13 compares the count result 30 with the threshold value 31 stored in the register 12, and the corrected identification result 26 is input to the detection means 14. For example, if it is determined that the original detection plate is the original detection plate when the identification reference is two or more pixels, the register 12 stores 1 and the comparator 13 determines that the count result 30 is larger than the threshold 31. "0" is output, otherwise "1" is output. As a result, the original is identified only in the cases of FIGS. 2 and 3, and the original detection plate is identified in the other cases of FIGS. 4 to 6. Here, it is assumed that the pixels marked with a circle in the frame are identified as the original detection plate. Further, it is possible to arbitrarily determine whether the result of identifying the document or the document detection plate is valid for all the pixels in the area or only the target pixel in the area.

The detection means 14 uses the corrected identification result 26 to
The original area is identified as described above.

[0024]

As described above, according to the present invention, the original and the original detecting plate are discriminated from each other not by the pixel but by setting the area and further providing the discrimination standard separately.
Even if the original has a color close to the reference value, the original and the original detection plate can be accurately identified, and the size of the original can be detected faithfully to the original.

[Brief description of drawings]

FIG. 1 is a configuration block diagram showing an embodiment of an image input / output device of the present invention.

FIG. 2 is an explanatory diagram showing an identification pattern.

FIG. 3 is an explanatory diagram showing an identification pattern.

FIG. 4 is an explanatory diagram showing an identification pattern.

FIG. 5 is an explanatory diagram showing an identification pattern.

FIG. 6 is an explanatory diagram showing an identification pattern.

FIG. 7 is a configuration block diagram showing a discriminating means.

FIG. 8 is a configuration block diagram showing a document area correction unit in the image input / output apparatus of the present invention.

FIG. 9 is a configuration block diagram showing a conventional example of an image input / output device.

FIG. 10 is a flowchart showing the operation of the detection means.

FIG. 11 is a timing chart showing the operation of the memory control means in the image input / output device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 original 2 original detecting plate 3 reading means 4 discriminating means 5 original area correcting means 14 detecting means

Claims (1)

[Claims] 1. An image input / output device for reading and displaying a document, wherein a document detection plate for pressing the document and distinguishing it from the document, a reading unit for reading the document or the document detection plate, and an image read by the reading unit. Compare the data with the reference data,
The document area includes a discriminating unit for discriminating between the document and the document detecting plate, a document region correcting unit for correcting the discrimination result of the discriminating unit, and a detecting unit for detecting the document region from the output of the document region correcting unit. The correction means includes a memory means for storing an identification result corresponding to image data around the image data currently being identified, and an identification result corresponding to the image data currently being identified and the image data around it in the original area. That there is
Alternatively, the image input / output device is provided with a counting means for counting the identification result indicating the original detection plate area and a comparing means for comparing the count value of the counting means with other reference data.