JP3480401B2 - Document reading apparatus and black streak detection method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applied to a facsimile machine, a scanner, a copying machine, and the like, and has an image reading device having a function of detecting black stripes due to impurities adhering to a stage glass or the like, and a black stripe due to impurities. The present invention relates to a black streak detection method.

[0002]

2. Description of the Related Art Generally, a facsimile apparatus or the like employs a method in which an original is conveyed and scanned by light to read image information from each scanning line. In an image reading apparatus applied to such a facsimile apparatus, light is blocked when impurities such as dust and dust are present on the optical path between the light source and the original. As a result, even when scanning a portion where no characters or the like are written, the pixel corresponding to the position where the impurity exists is read as black,
Black streaks occur in the image read from the conveyed document.

Therefore, various document reading apparatuses have been proposed which detect black streaks so that an operator can clean and remove impurities. For example, in Japanese Unexamined Patent Publication No. 6-303428, a logical operation of binarized information is performed for each pixel at the same position on each scanning line within one page, and the result of this logical operation is within one page. In the case where it is indicated that a black pixel has been read in all the lines, an image reading device that detects that a black streak has occurred at a position corresponding to the pixel is described.

Further, over a plurality of pages, a logical operation of binarized information is performed for each pixel at the same position on each scanning line, and the result of this logical operation indicates that a black pixel is read on each page. In the case shown, there is also described an image reading apparatus that detects the occurrence of black streaks at the position corresponding to the pixel. According to such an image reading apparatus, even if there is a page including ruled lines or the like in the document, it is possible to prevent erroneous detection of the ruled lines or the like as black streaks.

[0005]

However, such an image reading apparatus requires a large amount of memory. A line buffer for storing binary data of each pixel in the read scanning line to perform a logical operation for each pixel on the plurality of scanning lines, and a line for storing the result of the logical operation of each pixel in each already read line This is because a buffer and a line buffer that stores the result of the logical operation of each pixel stored in these two line buffers are required.

In order to prevent erroneous detection of ruled lines and the like as black streaks, it takes time to detect black streaks when reading an original over a plurality of pages. Furthermore, because it is configured to detect black streaks while reading the original,
When the original is read while eliminating the black streaks, it is necessary to read the original for detecting the black streaks and the original for obtaining the image in which the black streaks are eliminated, which is troublesome.

It is an object of the present invention to provide an image processing apparatus and a black streak detecting method which can detect a black streak without reading a document without requiring a large amount of memory.

[0008]

An image processing apparatus according to the present invention is provided with a roller for conveying a document to a scanning position, an optical information reading means for reading image information for each scanning line by scanning with light, and an optical information reading means for each scanning line. The binarizing means for binarizing the image information into black pixels and white pixels on a pixel-by-pixel basis, and the run length of white pixels, which is the number of consecutive white pixels on each scanning line, and the number of consecutive black pixels. A run length calculating means for obtaining a run length of a black pixel, a candidate position calculating means for calculating a position which is a candidate for a black streak on each scan line from a run length of a white pixel and a run length of a black pixel, and a scan position for each scan line When a position that is a candidate for a black streak has a specific positional relationship for a certain number of lines or more, it is determined that a black streak has occurred, and a black streak detection unit that detects the black streak is provided , and the candidate position calculation unit is provided .
Is the scan length from the white pixel run length and the black pixel run length.
The position where the white pixel changes to a black pixel on the in
Is calculated as the position where the white pixel is
The position where the black pixel changes is the same on the next scanning line
The relationship of position is established continuously for a certain number of lines or more.
When it stands, black is changed from the white pixel to the position of the black pixel.
It is characterized in that it is determined that streaks have occurred and black streaks are detected .

The image processing apparatus according to the present invention has a scanning position.
It is equipped with a roller that conveys the original on the
Optical information reading means for reading image information for each
The image information of the scanning line is divided into black pixels and white pixels in pixel units.
Binarization means for binarization and white pixels are connected on each scan line.
The run length of white pixels and the number of black pixels that are consecutive numbers are consecutive
A run length calculation means for obtaining the run length of the black pixel
On each scan line from the pixel run length and the black pixel run length
Position calculation means for calculating the position that is a candidate for black streaks
And the positions that are candidates for black streaks in each scan line are
When there is a specific positional relationship over a certain number of lines
Black streaks that detect black streaks by determining that black streaks have occurred
And a candidate position calculation means for detecting the white pixel run.
White pixel to black pixel calculated from the length and run length of black pixel
Number of pixels from the beginning of the scan line
Is defined as X, and the run length of the black pixel is defined as Y.
If Y is odd, then X + (Y + 1) / 2
Black the center position of consecutive black pixels on the scan line.
If the Y is an even number,
By X + Y / 2, the continuous black pixels on the scan line
The center position is calculated as the position that is
The edge detection means determines that the center position of consecutive black pixels is the next scan line.
The number of lines with a constant relationship of black pixels in
If the above conditions are continuously satisfied, the black streak is displayed at the center position of the black pixel.
Is characterized by detecting black streaks when it is determined that
It

The optical information reading means scans.
If there is a white roller in the position and the document is not in the scanning position,
Image information is read for each scanning line while rotating the roller.
It may be configured to take. With this configuration,
Scan by scanning the image of the rolling white roller
Black streaks due to impurities even when there is no document in the position
Can be detected.

Further , the black streak detecting means has a continuous black pixel.
If the run length of black pixels, which is the number of
In that case, specify the position that is a candidate for the black streak for that black pixel
With the configuration that excludes from the judgment target of whether or not there is a positional relationship
It may be. With such a configuration, black lines and originals
Because of the intersection with the characters such as
Detects black streaks even if there are scan lines that change sharply
be able to.

Further , when the black streak is detected, the black streak is detected.
It may have a black streak information output means for outputting the position.
Yes. With such a configuration, the operator should remove
You can know the position of impurities and clean them to remove impurities
By doing so, it is possible to eliminate black streaks.

Further , the optical information reading means is used to convey a document.
A glass that has a scale gauge as part of the path and transmits light.
The glass surface is provided in the black streak information output means.
With a configuration that displays the position of the black streak according to the scale gauge
It may be. With this configuration, the operator
The position of impurities can be known more easily.

The black streak detection method according to the present invention uses light.
Image information of a white roller that rotates every scan line
Information is read and the image information of each scan line is blacked in pixel units.
Binarization into pixels and white pixels, white pixels on each scan line
The run length of white pixels and the number of black pixels
The run length of black pixels, which is the number of
From the run length of black and white pixels, white pixels are black pixels on each scan line
Calculate the position that changes to as a position that is a candidate for black streaks
However, the position calculated as the position that is a candidate for black streaks is
The relationship of being at the same position on the scan line is constant
From the white pixel when the number of lines of
It is judged that a black streak has occurred at the changed black pixel position and black
It is characterized by detecting streaks.

Further, the black streak detection method according to the present invention is
Image information of a white roller that rotates for each scanning line is read by scanning with light, the image information of each scanning line is binarized into black pixels and white pixels in pixel units, and white pixels are continuous on each scanning line. obtains the run length of black pixels is the number of run length and the black pixels of white pixels are continuous is the number, the run of white pixels
White pixel to black pixel calculated from the length and run length of black pixel
Number of pixels from the beginning of the scan line
Is defined as X, and the run length of the black pixel is defined as Y.
If Y is odd, then X + (Y + 1) / 2
Black the center position of consecutive black pixels on the scan line.
If the Y is an even number,
By X + Y / 2, the continuous black pixels on the scan line
The center position is calculated as the position that is
Among consecutive black pixels calculated as the same candidate position
If the center position is a black pixel in the next scan line,
Black pixel when the relationship is established continuously for a certain number of lines or more
Detects black streaks by determining that black streaks have occurred at the center position of
It is characterized by doing.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of an image reading apparatus according to the present invention. here,
The case where the image reading apparatus is applied to a facsimile apparatus will be described. The control unit 7 is composed of a CPU, a ROM that stores a program, a RAM, and the like, and controls the image reading apparatus and the facsimile apparatus according to a predetermined program.

The user interface section 8 is composed of, for example, a key input section, an LCD, etc., and inputs an instruction for black streak detection by an operator and various settings, and displays the input settings. Further, the LCD or the like which constitutes the user interface unit 8 displays the position information of the detected black streak.

The document reading unit 1 controls the motor and the like to convey the document by the rollers, and passes the reading scanning line position existing on the conveyance path. The reading scanning line position is a position where the document reading device scans the document with light to read one line of image information, and this position is fixed. The document reading unit 1 reads the image information of the document for each scanning line, photoelectrically converts the read information, and outputs it as an analog signal to the AD conversion unit 2.

FIG. 2 is an explanatory view showing a state in which the document reading section 1 is viewed from the side. The document 11 is one page of the document read by the document reading device. Feeding roller 1
2 is composed of two rollers, and sends the document set by the operator to the white roller 13. The white roller 13 is a roller made of white rubber or the like, and is located above the reading / scanning line position. The white roller 13 guides the conveyed document 11 to the reading scanning line position. The discharge roller 14 is composed of two rollers and discharges the read document 11. The guide 15 is provided in the document conveyance path and conveys the document smoothly.

The lamp 16 irradiates light for scanning the document 11 existing at the reading scan line position. The light emitted by the lamp 16 scans the moving image of the document 11 line by line. The stage glass 17 constitutes a part of the conveyance path of the document 11 and also transmits the light emitted by the lamp 16 and the reflected light from the document 11. The mirror 18 guides the reflected light from the document 11 to the lens 19. The lens 19 is
The reflected light is condensed and guided to the CCD 20. The CCD 20 converts the incident light into an analog electric signal, and outputs this electric signal to the AD converter 2.

The A / D converter 2 further converts the image information of one scanning line converted into an analog electric signal into digital multi-valued data and outputs it to the image processor 3. The image processing unit 3 binarizes the image information converted into digital multi-valued data into black pixels and white pixels in pixel units, and performs various image processing such as edge enhancement processing and isolated point removal. The image processing unit 3 outputs the binarized image information to the storage coding unit 5 and the black streak detection unit 4.

The storage coding unit 5 compresses the binarized image information. Since the amount of data in the binarized image information is large,
It is compressed and accumulated. The storage encoding unit 5 uses, for example, IT
MH (Modified Huffman) code and MR (M
odified Read) code or MMR (Modified Modified)
Read) Encode by code. Also, other than the encoding according to the ITU-T recommendation, another encoding method may be adopted. The storage encoding unit 5 outputs the compressed image information to the memory unit 6, and the memory unit 6 stores this image information.

On the other hand, the black streak detecting section 4 detects a black streak from the binarized image information and generates black streak position information. FIG. 3 is a block diagram showing an example of the configuration of the black streak detector 4. The pixel run count unit 41 counts the number of consecutive white pixels and black pixels from the binarized information for one scanning line, and alternately obtains the run length of the white pixels and the run length of the black pixels. The run length of white pixels is the number of consecutive white pixels, and the run length of black pixels is the number of consecutive black pixels.

As an example, FIG. 4 shows image information for one scanning line in which white pixels and black pixels are lined up. In FIG. 4, the left end is the start position of the scanning line. From the head position, a white pixels are arranged. The run length of this white pixel is a. Next, b black pixels are lined up. The run length of this black pixel is b. The same applies to the next white pixel and black pixel. Therefore, in this example, the pixel run count unit 41 alternately sets the run lengths of the white pixel and the black pixel to a, b, and
Calculate as c, d, and e. The pixel run count unit 41
The obtained run lengths are output to the calculation unit 42.

The calculation unit 42 calculates the position where the white pixel changes to the black pixel from the run lengths of the white pixel and the black pixel. This change position is represented as the number of pixels, for example, when the black pixel is arranged next to the white pixel, the number of pixels from the beginning of the last pixel of the white pixels. The calculation unit 42 calculates the position where the white pixel changes to the black pixel as the sum of the run lengths from the head to the black pixel. Further, the change position may be expressed as the number of pixels from the beginning of the black pixel to the first pixel, but in the following description, the last pixel of the white pixels is changed from the white pixel to the black pixel. Change position of.

An example of changing position calculation will be shown below. In FIG. 4, the positions where the pixel type has changed are A, B, C, and D, and the position of the last pixel of the scanning line is E. The calculation unit 42 obtains the position where the white pixel is changed to the black pixel, and thus calculates A and C. The run length of the first white pixel is a
Therefore, the position A at which the white pixel changes to the black pixel is A
= A. Since the run lengths up to the next black pixel are a, b, and c, the position C at which the white pixel changes to the black pixel for the second time is calculated as C = a + b + c. As described above, the calculation unit 42 determines that the a-th pixel is a + b + c.
The pixel position is calculated as the change position. The calculation unit 42 outputs the calculated changed position to the comparison unit 43.

The black streak position data storage unit 44 stores the black streak position candidates obtained from the already read scanning lines, and when the comparison unit 43 inputs the change position from the white pixel to the black pixel, the black streak position data is stored. The line position candidates are output to the comparison unit 43. The candidate for the black streak position is a change position when the white pixel is changed to the black pixel at the common position in the already read scanning lines, and is input from the comparison unit 43 as described below.

The comparison section 43 compares the change position from the white pixel to the black pixel input from the calculation section 42 with the black streak position candidate input from the black streak position data storage section 44. As a result of comparison, if the candidate for the black streak position and the changed position input from the calculation unit 42 match, the candidate for the black streak position is left as it is. If the black streak position candidate does not match the change position input from the calculation unit 42, the black streak position candidate is excluded from the candidates. The comparison unit 43 outputs the black line position candidates that have not been excluded as a result of the comparison to the black line position data storage unit 44.

When the comparison unit 43 inputs the information of the first scanning line, the black streak position data storage unit 44 does not store the black streak position candidates. Therefore, the comparison unit 43
Does not compare with the black streak position candidate, and outputs the changed position input from the calculation unit 42 to the black streak position data storage unit 44 as a black streak position candidate. It should be noted that the last position of the white pixel is the change position from the white pixel to the black pixel, and thus the pixel at the position represented as the candidate for the black streak position is the white pixel, but here, for convenience, it is referred to as the candidate for the black streak position. .

The control unit 7 prepares a counter corresponding to each candidate at the black streak position, and when each candidate is not excluded from the candidates by the comparing unit 43, the counter of the candidates not excluded is incremented by one. . The initial value of this counter is 0. For example, the value of the counter corresponding to each change position where the white pixel is changed to the black pixel on the first scanning line is 1, and the counter value of the candidate for the black streak position not excluded by the comparison unit 43 by the m-th line is m. When the counter value exceeds a predetermined N, the control unit 7 detects a black pixel changed from a white pixel as a black streak.
N is set, for example, as the number of scanning lines for one page of the original document, but N may be set more or less than the number of scanning lines for one page of the original document. In addition, the control unit 7
Initializes the counter corresponding to the black line position candidates excluded by the comparison unit 43.

The control unit 7 displays the detected position of the black streak on the LCD or the like of the user interface unit 8. At this time, it is difficult for the operator to understand by displaying how many pixels the black pixel is from the beginning of the scanning line. Therefore,
It is desirable to display in a unit (for example, cm) that is easy for the operator to understand. Also, the stage glass 17
It is also desirable to add a scale to confirm the displayed position.

Next, the operation of detecting a black streak without setting the original will be described. When the control unit 7 receives a black streak detection instruction from the operator via the user interface unit 8, the control unit 7 rotates the white roller 13 and reads the image of the white roller 13 located above the read scan line position.
The CCD 20 converts the image information of each line into an A / D converter 2
Output to. The AD converter 2 converts the image information into digital multi-valued data, and the image processor 3 binarizes the multi-valued data into white pixels and black pixels. The image processing unit 3 inputs the binarized data to the pixel run count unit 41 for each scanning line.

The pixel run counting section 41 obtains the run length of white pixels and the run length of black pixels in each scanning line,
The calculation unit 42 obtains the position where the white pixel changes to the black pixel based on the run length. The comparison unit 43 stores the position where the white pixel is changed to the black pixel and the black streak position data storage unit 44.
The black streak position candidates input from are compared, and the candidates not excluded from the black streak position candidates are stored in the black streak position data storage unit 44. As described above, with respect to the first scanning line, the position where the white pixel is changed to the black pixel is stored in the position data storage unit 44 as a candidate for the black streak position. Control unit 7
When each candidate at the black streak position is not excluded from the candidates in the comparison unit 43, the counter value corresponding to the candidate not excluded is incremented by one. When the counter value exceeds the preset N, the control unit 7
The position of the black streak is displayed on the LCD or the like of the user interface unit 8.

FIG. 5 shows the white roller 1 without setting the original.
6 is an explanatory diagram showing an example of a read image when 3 is rotated. FIG. In FIG. 5, the read image 51 has one scanning line 52.
Each is shown separated by a broken line. Black streaks 53 occur while reading an image. In addition, when impurities such as dust adhere to the white roller 13, streaks 54 due to the roller impurities periodically occur as the white roller 13 rotates. By the operation of the image reading apparatus described above, the black streak 53 in which the change position from the white pixel to the black pixel is continuously the same for a certain number of lines (N) or more is detected, and the position is displayed on the user interface unit 8. . The streaks 54 due to roller impurities that are periodically generated do not have the same change position continuously for a certain number of lines (N) or more, and are not detected as black streaks.

Unlike the conventional document reading device, this document reading device can detect black streaks without providing a line buffer corresponding to each pixel of the scanning line, and has a feature that a large amount of memory is not required. Further, since the black stripes are detected without setting the originals, it is not necessary to set the originals for detecting the black stripes and to determine whether the originals are the black stripes or the ruled lines.
As a result, it is possible to detect the black streaks in a short time without the operator's trouble.

The accuracy of black streak detection by this document reading device will be described. If the impurities are floating debris,
The floating dust may slightly move while the white roller 13 rotates. Further, even if the impurities are adhesive dust, the position of the black pixel in the read image information may slightly shift in each scanning line due to the mechanical shift of the document reading unit 1. FIG. 6 shows an example of an image image when such a shift occurs. In FIG. 6, black pixels are displaced between the reading of the (P + 1) th line and the reading of the (P + 2) th line due to movement of floating dust. Therefore, the position of changing to a black pixel is different between the (P + 1) th line and the (P + 2) th line. As a result, P +
The count-up is not performed for the candidates for the black streak position in 2 lines, the counter is initialized, and it is no longer detected as a black streak. In this way, black streak detection accuracy may deteriorate for floating dust and the like.

Next, another embodiment of the present invention will be described. The document reading apparatus according to this embodiment has higher detection accuracy of black streaks than the case shown in the above-described embodiments. The configuration of the image reading apparatus in this embodiment is the same as that shown in FIGS. 1 to 3, but the operations of the calculation unit 42, the comparison unit 43, the black streak position data storage unit 44, and the control unit 7 are different.

The calculation unit 42 outputs not only the change position from the white pixel to the black pixel but also each run length of the black pixel to the comparison unit 43.

The black streak position data storage unit 44 stores candidates for the black streak center position obtained from the already read scanning line, and when the comparison unit 43 inputs the changed position and the run length from the calculation unit 42, The candidate for the black streak center position is output to the comparison unit 43. The candidate for the black streak center position is the position obtained as the black streak center position on the already read scanning line, and is input from the comparison unit 43 as described below.

The comparing section 43 calculates the position of the central pixel in the continuous black pixels as the black stripe center position. When the change position input from the calculation unit 42 is X and the run length of the black pixel is Y, the black stripe center position is X + when Y is an odd number.
It is calculated as (Y + 1) / 2. If Y is an even number,
Calculated as X + Y / 2. If Y is even, X +
It may be obtained as Y / 2 + 1. Also, the comparison unit 43
A range of black pixels is calculated, from which pixel to which pixel is a black pixel.

For example, in FIG. 4, assuming that b is an odd number and d is an even number, the center position of the black streak in the black pixel having the run length b is A + (b + 1) / 2. The black stripe center position in the black pixel having the run length d is C + d / 2.
As described above, A = a and C = a + b + c.

The comparison unit 43 puts the calculated black pixel range in the range of
It is determined whether or not the candidate for the black streak center position input from the black streak position data storage unit 44 is included. If the candidate black streak center position in the already read line is within the calculated black pixel range, the comparison unit 43 regards the calculated black streak center position as a candidate for the black streak center position and stores the black streak position data. It is output to the unit 44. If the black line center position as a candidate in the already read line is not within the calculated black pixel range, the black line center position candidate input from the black line position data storage unit 44 is excluded from the candidates.

The above operation will be described by taking as an example the case where the comparing unit 43 inputs the change position on the (P + 2) th line shown in FIG. 6 and the run length of the black pixel from the calculating unit 42. The black line center position of the (P + 2) th line calculated by the comparison unit 43 is
It is the (s + 2) th pixel, and the range of black pixels is the range from the (s + 1) th pixel to the (s + 3) th pixel. Further, the candidate of the black streak center position input from the black streak position data accumulating unit 44 by the comparing unit 43 is the black streak center position at the time of reading up to the (P + 1) th line and is the s + 1th pixel. At this time,
The candidate for the black stripe center position (s + 1st pixel) is the P + 2th pixel.
Range of black pixels in line (s + 1st pixel to s + th pixel
It is within the range of up to 3 pixels). Therefore, the comparison unit 43
Represents the calculated black streak center position (s + 2nd pixel) as a candidate for the black streak center position.
Output to.

When the comparing section 43 inputs the information of the first scanning line, the black streak position data accumulating section 44 does not store the candidate of the black streak center position. Therefore, the comparison unit 43 does not determine whether or not the candidate for the black streak center position is within the range of the black pixels, and calculates the black streak center position calculated from the change position and the run length input from the calculation unit 42 as It is input to the black streak position data storage unit 44 as a candidate for the black streak center position.

The control section 7 prepares a counter corresponding to a group of black pixels (including a group consisting of only one black pixel) continuous on the scanning line. When the candidate for the black streak center position is not excluded from the candidates by the comparison unit 43, the counter corresponding to the candidate for the black streak center position is incremented by one. When the counter exceeds the preset N, the control unit 7 displays the position of the black streak on the LCD or the like of the user interface unit 8. Further, the control unit 7 initializes the counter corresponding to the black line position candidates excluded by the comparison unit 43.

In the document reading apparatus according to this embodiment,
Whether or not the candidate obtained as the black streak center position in the already read scanning line is included in the range of black pixels of the newly read scanning line is determined as to be excluded from the candidate. This point is different from the document reading apparatus according to the above-described embodiment, but other operations are the same as those of the document reading apparatus described above.

According to the document reading apparatus of this embodiment, even if the floating dust or the like slightly moves during the rotation of the white roller 13, the count-up is not interrupted, and the black streak can be detected with higher accuracy. You can

Next, a description will be given of an embodiment in which a black line is detected while setting a document and reading image information of the document. The configuration of the image reading apparatus in this embodiment is the same as that shown in FIGS. 1 to 3, but the operations of the calculation unit 42, the comparison unit 43, and the control unit 7 are different.

First, the operation of detecting a black streak by using the change position from the white pixel to the black pixel as a candidate for the black streak position will be described. The calculation unit 42 outputs the change position from the white pixel to the black pixel and the run length of the black pixel to the comparison unit 43.
If the run length of the black pixel is equal to or greater than a certain length, the comparing unit 43 does not compare the change position where the black pixel is changed from the white pixel to the black pixel position candidate with respect to the black pixel. Further, for black pixels having a long run length, the black streak position candidates are not output to the black streak position data accumulating unit 44, and the position data accumulating unit 44 retains the data stored until then. The control unit 7 does not count up the counter corresponding to the candidate for the black streak position and does not initialize the counter.

Next, the operation for detecting a black streak by determining whether or not the candidate for the black streak center position is included in the range of black pixels in the next line will be described. The calculation unit 42
The change position from the white pixel to the black pixel and the run length of the black pixel are output to the comparison unit 43. If the run length of the black pixel is equal to or longer than a certain length, the comparing unit 43 determines that the black pixel is
It is not judged whether or not the black pixel center position candidate is included in the range of black pixels. For black pixels having a long run length, the center position of the black streak is not output to the black streak position data storage unit 44, and the position data storage unit 44 retains the data stored until then. The control unit 7 does not count up the counter corresponding to this black stripe position candidate,
Also, the counter is not initialized.

For a black pixel whose run length is less than a fixed length, the document reading apparatus performs the same operation as that of each embodiment when detecting a black line without setting the document. 1
When black pixels with a run length longer than a certain length and black pixels with a run length shorter than a certain length coexist on the scan line, black pixels with a run length longer than a certain length are excluded from comparison or judgment. However, black pixels whose run length is less than a certain length are subject to comparison and judgment as in the case of detecting black streaks without setting a document.

When the document 11 is set, the image reading device reads the image of the rotating white roller 13 until the document 11 reaches the reading scanning line position. Further, the image of the white roller 13 is read even after the image of the last scanning line of the document 11 is read and before the document of the next page reaches the reading scanning line position. While the document 11 is moving on the reading scan line position, the image of the document 11 is read.

FIG. 7 is an explanatory diagram showing an example of a read image when detecting a black streak while reading an image of a document. In FIG. 7, a document image 55 is an image read from the document 11. The area other than the area indicated by the original image 55 is an image obtained by reading the white roller 13. Original reading start line 5
Reference numeral 6 is a scanning line when the document 11 reaches the reading scanning line position. While reading from the first scanning line to the original reading start line 56, the black streak 53 and the streak 54 due to roller impurities are read. The same applies from the time when the last scan line of the document is read until the time when the document on the next page reaches the read scan line position. After reading the original reading start line 56, lines 5 due to impurities attached to the white roller 13 hidden by the original 11
4 disappears.

In FIG. 7, the black streak 53 is the character "A".
Intersects with. Since the horizontal spread of the first stroke of "A" is large, the run length of this black pixel is very long. Therefore, in the scanning line where the black stripes and “A” intersect, both the position where the white pixel changes to the black pixel and the central position of the black stripe are significantly different from the scanning lines before that. Comparison unit 4
For this black pixel, 3 does not compare the position information changed to a black pixel with the candidate for the black streak position, and does not determine whether the range of the black pixel includes the candidate for the black streak center position. That is, it is not set as a determination target for black streak detection. The scan line after the intersection of the black streak and the character or the like has a short run length, and is therefore a determination target for the black streak detection. Even if the black streak is not a determination target in some cases, the count-up is not interrupted, so that the black streak can be detected.

Black streaks can be detected even by the same operation as in each of the embodiments when black streaks are detected without setting the original. However, when the black streak intersects with a character or the like, the position at which the white pixel changes to the black pixel and the center position of the black streak are largely changed, so that the black streak detection accuracy is deteriorated. Therefore, when detecting a black streak while reading a document, it is desirable to use the above-described embodiment.

Even if a ruled line is drawn on the document 11, the image of this ruled line does not appear before the document reading start line 56 is read or between pages, so N is set to 1.
By setting more than the number of scanning lines for a page, ruled lines are not erroneously detected as black streaks.

The white roller 13 may not be white, and the image may be read only when the original 11 is present at the reading scan line position. However, in this configuration,
Black streaks cannot be detected without setting the original, and erroneous detection is easy when a ruled line or the like is written. Therefore, when the original is not present using the white roller 13, the white roller 13 is used. It is desirable to read the image.

In each of the above embodiments, the control unit 7 receives an instruction for black streak detection from the user interface unit 8 and does not display the detection result on the user interface unit 8, but remotely via the line. It may be configured to receive a black streak detection instruction from a remote place and display the detection result on a display device at a remote location.

Although the original reading apparatus applied to the facsimile apparatus is shown in the above embodiment, the image reading apparatus according to the present invention is also applied to a scanner, a copying machine and the like.

According to the present invention , the document is conveyed to the scanning position.
An image is provided for each scan line by scanning with light that is equipped with a roller
Optical information reading means for reading information and each scanning line
Binarize image information into black pixels and white pixels in pixel units 2
The digitizing means and the number of consecutive white pixels on each scan line.
Black image that is the run length of white pixels and the number of consecutive black pixels
Run length calculation means for obtaining the prime run length and the run length of white pixels
Of black lines on each scan line from the run length of black and black pixels
A candidate position calculation means for calculating a complementary position and each scan line
The number of lines where the position that is a candidate for black streaks in the in is constant
Black streaks are generated when there is a specific positional relationship over the above
Black streak detection means to detect black streak
The candidate position calculating means is provided with a run length of white pixels and a black image.
White pixels change to black pixels on each scan line from the raw run length
The calculated position is calculated as a position that is a candidate for black streaks, and
The same detection means detects that the position where the white pixel changes to the black pixel is the next
There is a certain relationship that it is the same position on the inspection line.
When the number of lines is continuously satisfied, the white pixel is changed.
It is determined that black streaks have occurred at the position of the black pixel
Since the line streaks are detected, a line buffer for storing binary data of each pixel is not required, and black streaks can be detected even if a large amount of memory is not provided. Also,
According to the present invention, a roller that conveys a document to the scanning position is provided.
Image information is read for each scanning line by scanning with light
Optical information reading means and image information of each scanning line
Binarizing means for binarizing black pixels and white pixels in units, and
Runs of white pixels, which is the number of consecutive white pixels on the scan line
Find the run length of black pixels, which is the number of consecutive long and black pixels
Run length calculation means, and the run length of the white pixel and the black pixel
From the run length, select the position that is a candidate for black streaks on each scan line.
Candidate position calculation means to calculate and black in each scan line
Positions that are candidates for stripes over a certain number of lines
If there is a specific positional relationship, it is determined that black streaks have occurred.
With a black streak detecting means for detecting a black streak
The calculation means calculates from the run length of white pixels and the run length of black pixels.
It is the change position from the white pixel to the black pixel that is output, and scanning
The position expressed as the number of pixels from the beginning of the line is X
If Y is an odd number when the run length of black pixels is Y
X + (Y + 1) / 2 for continuous on scan line
The center position of the black pixel
Calculated, and scan Y by X + Y / 2 if Y is an even number
The center position of consecutive black pixels on the line is defined as a black stripe candidate.
Is calculated as the position where
The pixel center position is a black pixel in the next scan line
When the above relationship holds continuously for a certain number of lines or more
It is judged that a black streak has occurred at the center position of the black pixel and
Since it is configured to detect the same, binary data of each pixel is registered.
Large amount of memory without needing a line buffer to store
Black streaks can be detected even if they are not turned on. Furthermore
In addition, floating dust may shift while scanning each line
Due to the mechanical deviation of the information reading means, black appears on the image information.
Even if the pixel position is shifted, it is possible to detect black streaks.
it can.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a document reading apparatus according to the present invention.

FIG. 2 is an explanatory diagram showing a state where a document reading unit is viewed from the side.

FIG. 3 is an explanatory diagram showing an example of the configuration of a black streak detection unit.

FIG. 4 is an explanatory diagram illustrating run lengths of black pixels and white pixels in one scanning line.

FIG. 5 is an explanatory diagram showing an example of a read image when a document is not set.

FIG. 6 is an explanatory diagram showing deviation of black pixels due to floating dust and the like.

FIG. 7 is an explanatory diagram showing an example of a read image when a document is set.

[Explanation of symbols]

1 Document reading section 2 A-D converter 3 Image processing section 4 Black streak detector 5 Storage encoder 6 memory section 7 control unit 8 User interface section 41 pixel run count unit 42 Operation part 43 Comparison Department 44 Black line position data storage unit

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H04N 1/40-1/409 H04N 1/46 H04N 1/60

Claims (8)

(57) [Claims] 1. An optical information reading unit which is provided with a roller for conveying an original document to a scanning position and which reads image information for each scanning line by scanning with light, and image information of each scanning line is composed of black pixels and white pixels in pixel units. And binarizing means for binarizing, and run length calculating means for obtaining a run length of white pixels, which is the number of white pixels consecutive on each scanning line, and a run length of black pixels, which is the number of consecutive black pixels. , A candidate position calculating means for calculating a position which is a candidate for a black streak on each scanning line from the run length of a white pixel and a run length of a black pixel, and the number of lines where the position which is a candidate for a black streak on each scanning line is constant The candidate position calculating means is provided with a black streak detecting means for detecting a black streak by determining that a black streak has occurred in the specific positional relationship described above , and the candidate position calculating means is a run length of white pixel and a black pixel
The length at which white pixels change to black pixels on each scan line
Position is calculated as a position that is a candidate for a black streak, and the black streak detection unit determines that the position where the white pixel changes to the black pixel is
The relationship is the same even in the scan line of
If the number of lines exceeds a certain number in a row, the white pixel
It is determined that black streaks have occurred at the position of the black pixel that changed from
A document reading device characterized by detecting black streaks . 2. A roller for feeding an original to a scanning position is provided.
Light that reads image information for each scanning line by scanning with fluorescent light
Scientific information reading means, and image information of each scanning line, black pixel and white pixel in pixel units
And a binarization unit for binarizing the white pixels, which is the number of consecutive white pixels on each scanning line.
And the run length of black pixels, which is the number of consecutive black pixels
Each scan line based on the run length calculation means to be obtained and the run lengths of white pixels and black pixels
Candidate position calculator that calculates the positions that are candidates for black lines above
Steps and the positions that are candidates for black streaks in each scan line are constant.
Black when there is a specific positional relationship over the number of lines
Black streak detection that detects streaks and detects black streaks
Means for calculating the run length of the white pixel and the run length of the black pixel.
It is the change position from white pixel to black pixel calculated from
Position represented as the number of pixels from the beginning of the scan line
Is X and the run length of the black pixel is Y, Y is an odd number
In the case of, on the scan line by X + (Y + 1) / 2
Position where the center position of consecutive black pixels is a candidate for black streak
When Y is an even number, it is calculated by X + Y / 2.
The black line on the center position of consecutive black pixels on the scan line.
Is calculated as the candidate position of the
There is a certain relationship that black pixels are
If the number of consecutive pixels is equal to or greater than
Characterized by detecting black streaks by determining that streaks have occurred
Document reading device. 3. The optical information reading means is provided at a scanning position.
If the original is not in the scanning position with a white roller,
Image information for each scanning line while rotating the camera
The document reading according to claim 1 or 2, characterized in that
apparatus. 4. The black streak detecting means is the number of consecutive black pixels.
If the run length of the black pixel is greater than a certain length,
The position that is the candidate for the black streak for the black pixel of
It is characterized by excluding from the judgment target of whether or not there is a relationship
The document reading device according to claim 1, 5. The position of the black streak is detected when the black streak is detected.
It is characterized by having a black streak information output means for outputting.
The document reading device according to claim 1. 6. An optical information reading means is provided in a document conveying path.
A glass surface that has a scale gauge as a part and transmits light
The black streak information output means is provided with an eye of the glass surface.
Characterized by displaying the position of the black streak according to the gauge
The document reading device according to claim 5. 7. Scanning by light rotates every scanning line
Up to read the image information of the white roller, and the black and white pixels of image information into pixel units in each scan line
Is binarized into white and the number of white pixels consecutive on each scan line
And the run length of black pixels, which is the number of consecutive black pixels
Find each scan line from the run length of white pixels and the run length of black pixels
The position where the white pixel changes to a black pixel above is a candidate for the black streak.
Calculated as that position, scanned calculated position follows as a candidate a position of the black stripe
There is a constant relationship that the position is the same on the line.
Change from the white pixel when the number of INs is satisfied continuously
It is judged that black streaks have occurred at the position of the black pixel
A method for detecting black streaks, which comprises detecting 8. The image information of a white roller that rotates for each scanning line by scanning with light is read, and the image information of each scanning line is binarized into black pixels and white pixels on a pixel-by-pixel basis. A white image calculated from the run length of white pixels and the run length of black pixels by obtaining the run length of white pixels, which is the number of consecutive white pixels, and the run length of black pixels, which is the number of consecutive black pixels.
It is the change position from the plain pixel to the black pixel and is the beginning of the scanning line
Let X be the position expressed as the number of pixels from
If Y is an odd number and Y is an odd number, X + (Y +
1) / 2, among the continuous black pixels on the scan line
The heart position is calculated as a position that is a candidate for black streaks, and Y is an even number.
In case of number, continuous on scan line by X + Y / 2
The center position of the black pixel
Calculated, successive calculated as the candidate a position of the black streaks black pixels
The center position of is a black pixel in the next scan line
Black if the relationship is established continuously over a certain number of lines
Judge that black streaks have occurred at the center position of the pixel and remove the black streaks.
Black streaks detection method and detecting.