JP2004222180A - Image processor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image processor for detecting and correcting a cause of a black stripe and white stripe-shaped defective pixel that occurs due to dust, etc., at the time of reading a transported original. <P>SOLUTION: This image processor 1 reads a whiteboard 5a provided at a reading position of the transported original G before original reading or at prescribed timing, compares an image signal at the time of reading the whiteboard 5a with a prescribed specified value for each pixel to detect a defective pixel, and performs abnormality decision processing for deciding an abnormal state when the number of pixels of the defective pixels is equal to or greater than the regulated number of pixels or when the number of continuous defective pixels is the regulated number of continuous pixels. In addition, when an abnormal state is decided, a warning is notified or reference data for shading correction of a defective pixel position is changed and corrected. Then, when there is a defective pixel to the extent of being practically a problem, the warning is notified or the reference data is corrected, and image quality can be improved at a low cost while improving availability. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image processing apparatus, and more particularly, to an image processing apparatus that detects and corrects the cause of black streak and white streak-like defective pixels generated by dust or the like when reading a conveyed document.
[0002]
[Prior art]
[Patent Document 1]
JP-A-11-112800
[Patent Document 2]
JP 2000-196881 A
2. Description of the Related Art Conventionally, an image processing apparatus that optically reads an image of a document, such as a scanner, a copying machine, and a facsimile, uses an SDF (sheet-through document feeder) to efficiently read a plurality of documents. Then, a plurality of documents are separated one by one and conveyed to a reading position of the reading unit, and a document conveyed over the contact glass of the reading unit is scanned by a light source of the reading unit arranged below the contact glass. The light is projected, the light reflected by the document passes through a predetermined optical path, and is incident on a photoelectric conversion element such as a CCD (Charge Coupled Device) to read the image of the document.
[0003]
In such an image processing apparatus, when dirt, dust, and other foreign substances (hereinafter, referred to as dirt) adhere to components on the optical path, the dirt or the like becomes black stripes, white stripes, or the like, and becomes an image. Appear and reduce image quality. Such deterioration of the image quality due to dust or the like frequently occurs particularly when the original is transported on the contact glass using the SDF and the original on the contact glass is read. This is because the document itself conveys dust and the like and attaches the dust and the like to the contact glass and the like under the influence of static electricity and the like.
[0004]
In view of the above, the present applicant has previously described, in an image processing apparatus having a function of optically reading an image and digitally processing the image, a reference plate data storage means for storing read data of a reference plate; From among the data stored in the data storage means, a reference plate abnormal data detecting means for detecting abnormal data whose output difference from adjacent data is equal to or greater than a predetermined value, and a reference plate abnormal data detecting means for detecting abnormal data. A reference plate abnormal value correction unit for correcting an abnormal value of the abnormal data with an output value of adjacent data, and the reference plate data storage unit using the output value of the abnormal data corrected by the reference plate abnormal value correction unit. There has been proposed an image processing apparatus including reference plate data rewriting means for rewriting the output value of the abnormal data (see Patent Document 1).
[0005]
That is, in the related art, when an abnormal value is detected when the reference plate is read, the abnormal value is rewritten with adjacent data and corrected so that the influence of dust or the like does not appear on the read image.
[0006]
Further, the present applicant has a first reading mode using a sheet-through document feeder and a second reading mode using a pressure plate. An image processing apparatus for converting information into a digitally converted image signal and processing the digitally converted image signal into an image signal that can be output as a visible image, wherein the first reading mode and the second reading mode (See Patent Document 2).
[0007]
That is, in this prior art, the output image is optimized by independently optimizing the reading correction when using the SDF and optimizing the reading correction when using the pressure plate.
[0008]
Conventionally, in an image processing apparatus that optically reads an image of a document such as a scanner device, a copying device, and a facsimile device, before reading the document or at a predetermined timing, a white reference plate is read and the white reference plate is read. The image data at the time of reading is stored as reference data, and the image data at the time of reading the document is corrected with the reference data, thereby making it possible to irradiate the light source irradiating the document and to adjust the sensitivity of the photoelectric conversion element such as a CCD. Shading correction for correcting variation is performed.
[0009]
[Problems to be solved by the invention]
However, in such a conventional technique, in addition to the normal shading correction, a correction means for correcting an abnormal image due to dust or the like is provided to improve the image quality. Regardless of whether the processing is performed by hardware or software, there is a risk that the circuit scale becomes large, the price increases, the processing time increases, and the usability deteriorates.
[0010]
Therefore, the present invention appropriately detects a defective pixel, and commonizes the correction after the detection with a normal shading correction process, thereby simplifying a circuit scale and suppressing an increase in a load on a circuit and software. It is another object of the present invention to provide an image processing apparatus with good usability that can shorten the processing time and improve the image quality at low cost.
[0011]
Therefore, the invention according to claim 1 irradiates at least a document to be conveyed with reading light from a reading unit which is stationary at a reading position, and converts reflected light of the reading light into image data by a photoelectric conversion element of the reading unit. When the image of the original is read and the shading correction is performed on the image data obtained by reading the original based on the reference data obtained by reading the white reference plate, when the original is not present in the original path at the reading position, the reading from the reading unit is performed. A white plate disposed at a position where light is irradiated is read by a reading unit before reading a document or at a predetermined timing, and a value indicating a density of an image signal when the white plate is read is set to a predetermined specified value and a pixel value. A defective pixel is detected by comparing each defective pixel, and if the number of defective pixels is equal to or greater than a predetermined specified number of pixels, an abnormality determination process for determining that the pixel is abnormal is performed. Without providing a large circuit or software for correcting the image, even if a defective pixel is detected, if the number of defective pixels is small enough to withstand practical use, continue reading the image without determining that it is abnormal, It is an object of the present invention to provide an image processing apparatus which can judge an abnormality when it becomes a problem in practical use and can process an image with good image quality at low cost while improving usability.
[0012]
According to a second aspect of the present invention, at least a document to be conveyed is irradiated with reading light from a reading unit stationary at a reading position, and reflected light of the reading light is converted into image data by a photoelectric conversion element of the reading unit. When the image of the original is read and the shading correction is performed on the image data obtained by reading the original based on the reference data obtained by reading the white reference plate, the reading light from the reading unit is output when there is no original in the original path at the reading position. The white plate provided at the position to be irradiated is read by the reading unit before reading the document or at a predetermined timing, and a value indicating the density of the image signal when the white plate is read is determined for each pixel by a predetermined specified value. If the number of consecutive defective pixels is equal to or greater than a predetermined specified number of consecutive pixels, an abnormal determination process is performed to determine that the pixel is abnormal. Without providing a large circuit or software to correct the error, even if a defective pixel is detected, if the defective pixel is not permanent but is temporary and practical enough to withstand practical use, it will not be judged as abnormal An image processing apparatus capable of continuing image reading, appropriately determining an abnormality when practically problematic, and improving the usability while processing an image with better image quality at low cost. It is intended to provide.
[0013]
The invention according to claim 3 enables the specified number of pixels or the specified number of continuous pixels to be changed as appropriate, and when the specified number of pixels or the specified number of continuous pixels is changed, the specified number of pixels or the specified number of continuous pixels is changed. By performing an abnormality determination based on the above, it is possible to appropriately change the abnormality determination level according to the usage environment of the image processing apparatus, the purpose of use of the user, and the like, and to provide an image processing apparatus with even better usability. The purpose is.
[0014]
According to a fourth aspect of the present invention, the white board is read by the reading means a plurality of times at different line positions, and the abnormality determination is performed based on an image signal obtained when the white plate is read at the line position with the fewest defective pixels. If it is not determined that there is an abnormality, the original is read at the line position where the number of defective pixels is the smallest, so that the detection position of dust, dirt, or the like that causes black streaks caused by the use environment or use condition of the image processing apparatus can be determined. To provide an image processing apparatus that can be used continuously even if the number of defective pixels is small so that it can be avoided in a state where it can be practically used even if an abnormality is recognized, thereby providing an image processing apparatus with better utilization. It is an object.
[0015]
According to the fifth aspect of the present invention, when it is determined that there is an abnormality, the abnormality notifying unit notifies the abnormality of the abnormality and outputs the reference data for shading correction of the defective pixel position from which the abnormality was determined. By performing either one of the correction processing and the change correction, the user can recognize the abnormality, or prevent the defective pixel from affecting the original read image, and appropriately prevent dust from adhering. It is an object of the present invention to provide an image processing apparatus capable of improving image quality while improving usability.
[0016]
According to the invention described in claim 6, when it is determined that there is an abnormality, the abnormality notification processing or the correction processing is performed in accordance with the selection by the selection unit that selects the abnormality notification processing and the correction processing, so that the user's purpose of use and utilization are performed. It is an object of the present invention to provide an image processing apparatus that enables a user to select abnormality notification and correction according to a mode, and that can improve image quality while further improving usability.
[0017]
[Means for Solving the Problems]
2. The image processing apparatus according to claim 1, wherein at least a document to be conveyed is irradiated with reading light from a reading unit that is stationary at a reading position, and reflected light of the reading light is converted into image data by a photoelectric conversion element of the reading unit. In the image processing apparatus which reads the image of the original after converting the image into the original data and performs shading correction on the image data obtained by reading the original based on the reference data obtained by reading the white reference plate, the original exists in the original path at the reading position. A white plate is provided at a position where the reading light from the reading unit is irradiated when the white plate is not read, and the white plate is read by the reading unit before reading the document or at a predetermined timing, and an image signal when the white plate is read is read. A defective pixel is detected by comparing the value indicating the density of each pixel with a predetermined specified value, and if the number of pixels of the defective pixel is equal to or larger than the predetermined specified number of pixels, an abnormal By performing the abnormality determination process to determine that that has achieved the above objects.
[0018]
According to the above configuration, at least the document to be conveyed is irradiated with reading light from the reading unit that is stationary at the reading position, and the reflected light of the reading light is converted into image data by the photoelectric conversion element of the reading unit, and the image of the document is read. When reading a document, and performing shading correction on the image data obtained by reading the document based on the reference data obtained by reading the white reference plate, the reading light from the reading unit is irradiated when the document does not exist in the document path at the reading position. A white plate disposed at a position where the white plate is read by the reading means before reading the document or at a predetermined timing, and a value indicating the density of the image signal when the white plate is read is compared with a predetermined specified value for each pixel. If the number of defective pixels is equal to or greater than a predetermined specified number of pixels, an abnormality determination process for determining that the pixel is abnormal is performed. Even if a defective pixel is detected and the number of defective pixels is small enough to withstand practical use without providing the circuit or software of the above, the image reading is continued without judging that there is an abnormality, and there is a practical problem. An abnormality can be determined to a certain degree, the usability can be improved, and an image with good image quality can be processed at low cost.
[0019]
3. The image processing apparatus according to claim 2, wherein at least a document to be conveyed is irradiated with reading light from a reading unit that is stationary at a reading position, and reflected light of the reading light is converted into image data by a photoelectric conversion element of the reading unit. An image processing apparatus that reads an image of a document and performs shading correction on the image data obtained by reading the document based on reference data obtained by reading a white reference plate, when a document does not exist in the document path at the reading position. A white plate is provided at a position where the reading light from the reading unit is irradiated, and the white plate is read by the reading unit before the document is read or at a predetermined timing, and the density of the image signal when the white plate is read is read. The defective pixel is detected by comparing the value indicating the pixel value with a predetermined specified value for each pixel, and if the number of consecutive defective pixels is equal to or greater than the predetermined specified number of consecutive pixels, it is abnormal. By performing the abnormality determination process to determine that has achieved the above objects.
[0020]
According to the above configuration, at least the document to be conveyed is irradiated with reading light from the reading unit that is stationary at the reading position, and the reflected light of the reading light is converted into image data by the photoelectric conversion element of the reading unit, and the image of the document is read. When reading a document, and performing shading correction on the image data obtained by reading the document based on the reference data obtained by reading the white reference plate, the reading light from the reading unit is irradiated when the document does not exist in the document path at the reading position. A white plate disposed at a position where the white plate is read by the reading means before reading the document or at a predetermined timing, and a value indicating the density of the image signal when the white plate is read is compared with a predetermined specified value for each pixel. If the number of consecutive defective pixels is equal to or greater than a predetermined specified number of consecutive pixels, an abnormality determination process for determining that the pixel is abnormal is performed. Without providing a large circuit or software, even if a defective pixel is detected, if the defective pixel is not permanent but is temporary and is of sufficient degree for practical use, the image can be read without determining that it is abnormal. Can be appropriately determined to be abnormal when it becomes a practical problem, the usability can be improved, and an image with better image quality can be processed at low cost. .
[0021]
In each of the above cases, for example, as described in claim 3, the image processing device can appropriately change the specified pixel number or the specified pixel continuation number, and the specified pixel number or the specified pixel continuation number is When changed, the abnormality determination may be performed based on the specified number of pixels or the specified number of consecutive pixels after the change.
[0022]
According to the above configuration, the specified pixel number or the specified pixel continuation number can be changed as appropriate, and when the specified pixel number or the specified pixel continuation number is changed, the specified pixel number or the specified pixel continuation number is changed based on the changed specified pixel number or the specified pixel continuation number. In this case, the abnormality determination level can be appropriately changed according to the usage environment of the image processing apparatus, the purpose of use of the user, and the like, and the usability can be further improved.
[0023]
Further, for example, as described in claim 4, the image processing apparatus performs the reading of the white plate by the reading unit a plurality of times at different line positions and reads the white plate at a line position with the least number of defective pixels. The abnormality determination may be performed based on an image signal, and when the abnormality determination does not determine an abnormality, the document may be read at a line position where the number of defective pixels is the least.
[0024]
According to the above configuration, reading of the white plate by the reading unit is performed a plurality of times at different line positions, and an abnormality determination is performed based on an image signal obtained when the reading is performed at the line position with the fewest defective pixels. If it is not determined, the original is read at the line position where the number of defective pixels is the smallest, so that the detection position of dust, dirt, etc., which causes black streaks caused by the use environment or use condition of the image processing apparatus, should be adjusted. Thereby, even if the number of defective pixels is small and an abnormality is recognized, it is possible to avoid the state where it can be practically used, and it is possible to continue using the apparatus, and the usability can be further improved.
[0025]
Further, for example, as described in claim 5, the image processing apparatus includes a predetermined abnormality notification unit, and when the abnormality is determined, the abnormality notification unit outputs a notification that the abnormality is present. Any one of a process and a correction process for changing and correcting the reference data of the defective pixel position from which the abnormality is determined may be performed.
[0026]
According to the above configuration, when it is determined that there is an abnormality, the abnormality notifying unit notifies the abnormality of the abnormality and outputs the abnormality, and changes and corrects the reference data of the shading correction of the defective pixel position on which the abnormality is determined. Or correction processing, which allows the user to recognize the abnormality or prevent the defective pixel from affecting the read image of the original, and appropriately prevent dust from adhering. By coping with this, the usability can be improved and the image quality can be improved.
[0027]
Further, for example, as described in claim 6, the image processing device includes a selection unit that selects the abnormality notification process and the correction process. The abnormality notification processing or the correction processing may be performed accordingly.
[0028]
According to the above configuration, when it is determined that the abnormality is abnormal, the abnormality notification processing or the correction processing is performed according to the selection by the selection unit that selects the abnormality notification processing and the correction processing. Thus, the user can select between the abnormality notification and the correction, so that the usability can be further improved and the image quality can be improved.
[0029]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the embodiments described below are preferred embodiments of the present invention, and therefore, various technically preferred limitations are added. However, the scope of the present invention is not limited to the following description. The embodiments are not limited to these embodiments unless otherwise specified.
[0030]
1 to 9 are diagrams showing an embodiment of the image processing apparatus of the present invention, and FIG. 1 is a schematic front view of an image reading apparatus 1 to which the embodiment of the image processing apparatus of the present invention is applied. FIG.
[0031]
In FIG. 1, an image reading apparatus (image processing apparatus) 1 is provided with a document reading table 3 on an upper part of a main body housing 2, and the document reading table 3 is usually provided with a contact glass. An upper part of the original reading table 3 is provided with an openable and closable original pressing plate 4. The original pressing plate 4 makes the original G set on the original reading base 3 adhere to the contact glass of the original reading base 3. Press down on.
[0032]
A document feeder 5 is provided on the upper right side of the main body 2 of FIG. 1, and the document feeder 5 includes an SDF (sheet-through document feeder) unit 6 and a document table 7. . A stepping motor 8 is provided in the SDF unit 6, and a plurality of originals G are placed on the original table 7 in an overlapping manner.
[0033]
The document feeder 5 separates a plurality of documents G placed on a document table 7 one by one by an SDF unit 6, and separates a separation roller 17 and a transfer roller 18 that are driven to rotate by a stepping motor 8. At 19 (see FIG. 3), the document is passed through the document reading table 3 and conveyed onto a discharge tray (not shown).
[0034]
A white reference plate 9 for shading correction is provided at an end of the document reading table 3 on the SDF unit 6 side. The document feeder 5 has an integral structure with the document pressing plate 4. When the document pressing plate 4 is opened, the document feeding device 5 is also opened and closed together.
[0035]
A contact glass window 3a is formed in the document conveying path on the upper surface of the main body housing 2 in which the document conveying device 5 is disposed, and the inside of the SDF unit 6 above the position where the contact glass window 3a is formed. Is provided with a transmission glass 3b and a white plate 5a. The white plate 5a is read on an optical path passing through the contact glass window 3a and the transmission glass 3b, particularly when detecting whether dust or the like is attached to the contact glass window 3a.
[0036]
An exposure scanning optical system (reading means) 15 including a first traveling body 10, a second traveling body 11, a lens 12, a CCD (Charge Coupled Device) 13, a stepping motor 14, and the like is disposed inside the main body housing 2. The first traveling body 10 has a light source 10a and a mirror 10b, and the second traveling body 11 has mirrors 11a and 11b.
[0037]
The exposure scanning optical system 15 is configured such that the first traveling body 10 and the second traveling body are moved in the horizontal direction (sub-scanning direction) by the stepping motor 14, and the light source 10 a on the first traveling body 10, such as a fluorescent lamp, The original G placed on the reading table 3 is irradiated with light, and the reflected light of the light reflected by the original G is reflected toward the second traveling body 11 by the mirror 10b on the first traveling body 10, Light incident from the first traveling body 10 is sequentially reflected by the mirrors 11 a and 11 b on the second traveling body 11 and emitted toward the lens 12. The lens 12 condenses and irradiates the light incident from the second traveling body 11 to the CCD 13. The CCD (line sensor) 13 has a plurality of one-dimensionally arranged CCD elements as photoelectric conversion elements, photoelectrically converts incident light incident from the lens 12, and outputs analog image data (image signals). . Further, the exposure scanning optical system 15 irradiates the white reference plate 9 with light, makes the reflected light from the white reference plate 9 incident on the CCD 13 in the same manner as described above, and outputs the same as reference data for shading correction.
[0038]
As shown in FIG. 2, the image reading device 1 opens the document holding plate 4 to read the image of the document G placed on the document reading table 3 as a document reading mode, and FIG. As shown in the drawing, the plurality of rollers 17 to 19 are rotated by the stepping motor 8 of the SDF unit 6 by using the automatic paper feeder 2 so that the plurality of originals G placed on the original There is an SDF mode in which the document G is conveyed to a predetermined reading position of the contact glass window 3a, and the document G is irradiated with light from the light source 10a of the first traveling body 10 that stops to read the image of the document G.
[0039]
In the book mode, the image reading apparatus 1 turns on the light source 10a when the document pressing plate 4 is opened and the document G is set on the document reading table 3 as shown in FIG. The plate 9 is read to obtain reference data for shading correction, and then the stepping motor 14 is driven to move the first traveling body 10 and the second traveling body 11 so that the optical path length from the document G to the CCD 13 is reduced. The document G is moved in the sub-scanning direction while being fixed, and the image of the document G on the document reading table 3 is read.
[0040]
In the SDF mode, when a plurality of documents G are set on the document table 7 in the SDF mode, first, the light source 10a is turned on, and the white reference plate 9a is turned on. After the reading, the first traveling body 10 is moved to the reading position of the contact glass window 3a and stopped by driving the spring motor 14. Next, the image reading apparatus 1 drives the stepping motor 8 to separate the documents G set on the document table 7 one by one by the separation roller 17 and transports the documents G by the transport rollers 18 and 19. The carriage 10 is transported to a predetermined reading position. At this time, the original G is conveyed at a constant speed, and the original G conveyed from the light source 10a on the first traveling body 10 through the contact glass window 3a while the first traveling body 10 and the second traveling body 11 are stopped. And the light from the original G reflected by the original G is reflected again by the mirror 10 b and the mirrors 11 a and 11 b on the second traveling body 11 through the contact glass window 3 a and passes through the lens 12. The light is incident on the CCD 13, photoelectrically converted by the CCD 13, and the image of the original G is read.
[0041]
In the SDF mode, the image reading device 1 detects the presence or absence of dust or the like on the contact glass window 3a at an abnormality detection timing, for example, before reading the document G or at a predetermined timing. The white plate 5a is read through 3a and the transmission glass 3b, and an image signal obtained by reading the white plate 5a is acquired as a detection image signal Sc (see FIGS. 7 and 8).
[0042]
The image reading apparatus 1 has a circuit block configuration as shown in FIG. 4 and includes a CPU (Central Processing Unit) 20, a ROM (Read Only Memory) 21, a RAM (Random Access Memory) 22, a light source driver 23, and a light source 10a. , A CCD driving unit 24, a CCD 13, an image processing unit 25, a scan buffer 26, a buffer controller 27, an I / F controller 28, a motor driver 29, a stepping motor 14, a motor driver 30, a stepping motor 8, and the like.
[0043]
The ROM 21 stores various programs such as a basic processing program as the image reading apparatus 1 and an abnormality determination processing program to be described later, and various data necessary for executing these various programs. Various data necessary for the operation of the device 1 are stored. The CPU 20 controls each unit of the image reading apparatus 1 based on the program in the ROM 21 while using the RAM 22 as a work memory, executes a sequence as the image reading apparatus 1, and performs an abnormality determination process described later. .
[0044]
The light source 10a is controlled to be turned on and off by a light source driver 23 under the control of the CPU 20, and the CCD 13 is driven by a CCD driving unit 24 to output photoelectrically converted image data to an image processing unit 25.
[0045]
The stepping motor 8 is driven by a motor driver 30, and the stepping motor 14 is driven by a motor driver 29.
[0046]
A scanner buffer (image data storage unit) 26 is connected to the image processing unit 25. The image processing unit 25 includes an analog video processing unit 41, a shading correction processing unit 42, and an image data processing unit, as shown in FIG. A unit 43, a timing generation unit 44, a binarization processing unit 45, and the like are provided.
[0047]
The analog video processing unit 41 receives an analog image signal Sa output from the CCD 13. The analog video processing unit 41 converts the analog image signal Sa into digital data and outputs the digital image data to the shading correction processing unit 42. I do.
[0048]
The shading correction processing unit 42 stores the image data when the white reference plate 9 is read as reference data for shading correction in the internal RAM, and performs the shading correction based on the image data when the document G is read based on the reference data. And outputs the image data after the shading correction to the image data processing unit 43.
[0049]
The image data processing unit 43 performs various types of image processing on the image data subjected to the shading correction by the shading correction processing unit 42 based on the enable signal EN input from the timing generation unit 44, and sends the image data to the binarization processing unit 45. The binarization processing unit 45 converts the image-processed image data into binary data or multivalued data (for example, 8 bits) by irreversibly compressing the image data, and outputs the converted data to the scanner buffer 26. , Expands the compressed image data in the scanner buffer 26. The image data processing unit 43 stores, for example, image data for several lines in a line buffer, forms a matrix, and performs a spatial filtering process or the like on the image data. The timing generator 44 outputs a stepping pulse SP to the motor driver 29 and the motor driver 30 to control the drive timing of the stepping motor 14 and the stepping motor 8 via the motor driver 29 and the motor driver 30.
[0050]
The binary or multi-valued image data Sb subjected to the image processing in the image processing unit 25 is accumulated in the scan buffer 26 under the control of the buffer controller 27, and other information (not shown) is transmitted via the I / F controller 28. The data is output to a processing device, for example, a personal computer.
[0051]
The image processing unit 25 includes a preamplifier circuit 51, a variable amplifier circuit 52, an A / D converter 53, a black operation circuit 54, a shading correction operation circuit 55, a line buffer 56, and the like, as shown in detail in FIG. ing.
[0052]
The image reading apparatus 1 condenses reflected light, which is emitted from the light source 10 a onto the original G on the original reading table 3, through the shading adjustment plate 16 by the lens 12, and forms an image on the CCD 13. In FIG. 6, a mirror for folding the reflected light is omitted for simplification of the description. Further, the shading adjustment plate 16 plays a role of adjusting the amount of light for eliminating the difference in the amount of reflected light between the center and the end of the CCD 13. That is, if there is too much difference in the amount of reflected light between the central portion and the end of the CCD 13 in the shading calculation process, only a calculation result including a large amount of distortion can be obtained. After the disappearance, the shading calculation process is performed.
[0053]
The preamplifier circuit 51 and the variable amplifying circuit 52 constitute the analog video processing unit 41, and the A / D converter 53, the black operation circuit 54, the shading correction operation circuit 55, and the line buffer 56 constitute the shading correction processing unit 42. Is composed.
[0054]
Then, the image data processing unit 43 performs various necessary image processing on the image data subjected to the shading correction input from the shading correction processing unit 42 and outputs the processed data to the binarization processing unit 45.
[0055]
In the image reading apparatus 1, as shown in FIG. 7, the defective pixel detection unit 60 is connected to the CPU 20 via the I / F controller 70, and the defective pixel detection unit 60 includes a binarization processing unit 61, A defective pixel holding unit 62 and an SRAM (Static RAM) 63 are provided.
[0056]
The binarization processing unit 61 of the defective pixel detection unit 60 detects the analog detection of one line output by the CCD 13 when the white plate 5a is read before the reading of the document G or at a predetermined timing at the abnormality detection timing. The image signal Sc for input is input, and the binarization processing unit 61 binarizes the input one-line analog image signal for detection Sc and outputs it to the defective pixel holding unit 62 as defect detection image data. .
[0057]
The defective pixel detection section 60 detects a defective pixel when the binarization processing section 61 binarizes the detection image signal Sc.
[0058]
That is, when the white pixel 5a is read through the contact glass window 3a, the result pixel detection unit 60 reflects the reflected light reflected by the white plate 5a by a shield such as dust attached on the optical path of the contact glass window 3a. A defective pixel generated by blocking light from being incident on the white plate 5a is detected. When the reflected light reflected by the white plate 5a is blocked by dust or the like and the reflection from the dust or the like is small, the dust is displayed on the upper side of FIG. As shown as a and dust b, the amount of light incident on the CCD 13 decreases, and the density of defective pixels increases. Therefore, in the binarization by the binarization processing unit 61, the level of a predetermined detection threshold (prescribed value) is set in advance as, for example, a detection threshold in FIG. When the binarization processing section 61 performs binarization processing, a defective pixel due to adhesion of dust or the like is converted into “1”, and a normal pixel is converted into “0”.
[0059]
When the detection start signal is input and the detection start signal is enabled, the defective pixel holding unit 62 stores the defect detection image data binarized by the binarization processing unit 61 in the SRAM 63, thereby performing the defect pixel detection processing. I do. That is, when the detection start signal is enabled, the defective pixel holding unit 62 performs binarization processing in the binarization processing unit 61, and stores defect detection image data, which is a detection result of detecting a defective pixel, in the SRAM 63. The defect detection image data is stored in the SRAM 63 by the defective pixel holding unit 62 in a state where the address of the SRAM 63 and the pixel position of the CCD 13 correspond to each other.
[0060]
Then, the CPU 20 reads out the defect detection image data stored in the SRAM 63 via the I / F controller 70 and, based on the defect detection image data, reads an abnormal pixel in reading the image of the original G due to dust or the like on the optical path. An abnormality determination process is performed to determine whether an abnormality has occurred based on whether or not an error has occurred.
[0061]
Next, the operation of the present embodiment will be described. The image reading apparatus 1 according to the present embodiment reads the white plate 5a at the abnormality detection timing, that is, before reading the original G or at a predetermined timing when reading the original G in the SDF mode, and contacts the white plate 5a with the contact glass on the optical path. The presence or absence of a defective pixel due to adhesion of dust or the like on the optical path of the window 3a is detected, and a warning or a change correction of the reference data for shading correction is performed.
[0062]
That is, in the image reading device 1, after a plurality of documents G are set on the document table 7 of the document transport device 5, various operations necessary for reading the document G are performed, and then a start key is input by the operation unit. The CPU 20 determines that the reading is in the SDF mode, moves the first traveling body 10 to the position of the white reference plate 9a, turns on the light source 10a, and reads the white reference plate 9a. Then, the first traveling body 10 is moved to the position of the contact glass window 3a and stopped. Thereafter, the CPU 20 drives the stepping motor 8 to separate the originals G set on the original platen 7 one by one by the separation roller 17 and transport the originals by the transporting rollers 18 and 19. The sheet is transported to the reading position. At this time, the original G is conveyed at a constant speed, and the original G conveyed from the light source 10a on the first traveling body 10 through the contact glass window 3a while the first traveling body 10 and the second traveling body 11 are stopped. And the light from the original G reflected by the original G is reflected again by the mirror 10 b through the contact glass window 3 a and the mirrors 11 a and 11 b on the second traveling body 11, and is transmitted to the CCD 13 through the lens 12. The image is read, the image is photoelectrically converted by the CCD 13, and the image of the document G is read.
[0063]
In the reading in the SDF mode, the CPU 20 turns on the light source 10a to read the white plate 5a through the contact glass window 3a at the abnormality detection timing, that is, before reading the document G or at a predetermined timing. An image signal obtained when the white plate 5a is read is input to the binarization processing unit 61 of the defective pixel detection unit 60 as a defect detection image signal Sc. The binarization processing unit 61 binarizes the defect detection image signal Sc with a predetermined detection threshold, thereby detecting a defective pixel and outputting it to the defective pixel holding unit 62 as defect detection image data. The holding unit 62 stores the detected defect detection image data in the SRAM 63 in association with the address of the SRAM 63 and the pixel position in synchronization with the enable of the detection start signal. In the defect detection pixel data stored in the SRAM 63, as described above, the defective pixel due to the attachment of dust or the like is “1”, and the normal pixel is “0”.
[0064]
Then, the CPU 20 counts the number of defective pixels in the SRAM 63, and if the counted number of defective pixels is equal to or larger than a predetermined number of pixels, when the original G is read, black streaks or white streaks are read. It is determined that there is an abnormal state in which image quality is degraded due to occurrence of an abnormal pixel, and a warning is displayed by displaying a display on the display unit of the image reading device 1 or outputting a warning sound.
[0065]
The CPU 20 determines the presence or absence of the abnormal state based on a predetermined number of pixels set in advance. The specified number of pixels is not only set in the initial setting of the image reading apparatus 1 but also determined by the operation. The user of the image reading apparatus 1 can arbitrarily set the setting from a unit or the like.
[0066]
If the specified number of pixels is set to, for example, “2”, the number of defective pixels exceeding the detection threshold is “2” in the case of FIG. However, if the specified number of pixels is set to, for example, “3”, it is not determined that the state is abnormal.
[0067]
That is, by setting the specified number of pixels to a small value, it is possible to determine the abnormal state even for fine dust and the like, and to improve the image quality. Conversely, by setting the specified number of pixels to a large value, It can be set as a state in which the user of the apparatus 1 reads an image having an acceptable image quality.
[0068]
When detecting an abnormal state, the image reading device 1 not only issues a warning as described above, but also changes the reading position of the first traveling body 10 with respect to the contact glass window 3a when reading the white plate 5a. Alternatively, the document G may be read after the abnormal state is resolved.
[0069]
That is, as described above, the reading positions of the white plate 5a and the document G are set in advance as the position A in FIG. 9, for example, but when the reading is performed at the position A as shown in FIG. If the three attached dust particles a, b, and c become defective pixels and the specified number of pixels is, for example, “3”, the CPU 20 determines that the state is abnormal.
[0070]
In this case, the CPU 20 moves the first traveling body 10 so that the reading position changes from the position A (line) to the position B (line), performs the defective pixel detection operation process again, and determines the abnormal state. I do. As can be seen from FIG. 9, when the reading position is changed to the position B, the number of defective pixels is “1” because the defective pixel detected is only dust a, and the CPU 20 determines that the state is abnormal. do not do.
[0071]
Then, the CPU 20 causes the document G to be read at the B position without issuing a warning.
[0072]
In this way, the user of the image reading apparatus 1 can read an image of good image quality without performing a process for responding to the warning, improving the usability and improving the image quality of the read image. Quality can be improved.
[0073]
Further, when detecting an abnormal state, the image reading device 1 may perform correction correction of the reference data for shading correction.
[0074]
That is, as described above, the defect detection pixel data is stored in the SRAM 63 in correspondence with the address of the SRAM 63 and the pixel position, so that the pixel position of the defective pixel can be known. On the other hand, in the image reading apparatus 1, as described above, the image data obtained when the shading correction processing unit 42 reads the white reference plate 9 is stored in the internal RAM as the reference data for shading correction. Of the reference data, as shown in the lower part of FIG. 8, the reference data of the pixel at the dust position (defective pixel position) is changed to dark data, and normal shading correction is performed to skip to white. When the shading correction data of the pixel at the defective pixel position is corrected to dark data in this way, it is possible to appropriately perform conversion to white for a pixel that becomes a black streak without performing complicated arithmetic correction processing, Image quality can be improved at low cost.
[0075]
Further, the determination of the abnormal state is not limited to the determination based on the number of detected defective pixels, and may be determined based on, for example, the number of consecutive detected pixels (the number of consecutive defective pixels). .
[0076]
In this case, when a defective pixel is detected, it is determined whether the next pixel is a defective pixel and the number of consecutive defective pixels is counted, or when it is determined that a certain pixel is a defective pixel, the pixel before the defective pixel is determined. The number of consecutive defective pixels is counted, and the number of consecutive defective pixels is detected.
[0077]
When the CPU 20 counts the number of consecutive defective pixels in the SRAM 63 and obtains the number of consecutive defective pixels, the CPU 20 determines that the obtained number of consecutive defective pixels is equal to or greater than a predetermined specified number of consecutive pixels. It is determined that an abnormal pixel such as a black streak or a white streak occurs when reading G, and the image quality is degraded, and as described above, it is determined that there is an abnormality in the display unit of the image reading apparatus 1. The warning is given by a warning method such as displaying or outputting a warning sound, and as shown in FIG. 9, the reading position in the contact glass window 3a is changed, or the change of the shading correction data is corrected. .
[0078]
Further, the image reading apparatus 1 performs the determination as to whether or not the pixel is a defective pixel by performing a binarization process at a predetermined detection threshold level set by the binarization processing unit 61. The detection threshold level may be arbitrarily set by the user of the image reading apparatus 1 by operating a key on the operation unit.
[0079]
For example, by lowering the level of the detection threshold (specified value), even fine dust and the like can be detected as defective pixels, and the image quality can be improved. Conversely, by raising the level of the detection threshold, image reading can be performed. It can be set as a state in which the user of the apparatus 1 reads an image having an acceptable image quality.
[0080]
Further, when the image reading apparatus 1 determines that the image reading apparatus is in the abnormal state, the image reading apparatus 1 operates a selection button (selecting unit) for selecting whether to issue a warning as described above or to automatically change and correct the shading correction reference data. And the like, and the automatic change correction of the warning or the reference data may be executed according to the selection by the selection button.
[0081]
As described above, the image reading apparatus 1 according to the present embodiment is arranged at a position where the reading light from the first traveling body 10 of the exposure scanning optical system 15 is irradiated when the document G does not exist in the document path at the reading position. The white plate 5a provided is read before the document is read or at a predetermined timing, and a value indicating the density of the image signal when the white plate 5a is read is compared with a predetermined specified value (detection threshold) for each pixel to detect a defect. An abnormality determination process is performed in which a pixel is detected, and if the number of defective pixels is equal to or greater than a predetermined specified number of pixels, the pixel is determined to be abnormal.
[0082]
Therefore, without providing a large circuit or software for correcting an abnormal image, even when a defective pixel is detected, if the number of defective pixels is small enough to withstand practical use, image reading can be performed without determining that the image is abnormal. It is possible to continuously determine an abnormality when it becomes a problem in practical use, improve the usability, and process an image with good image quality at low cost.
[0083]
In addition, the image reading device 1 of the present embodiment performs an abnormality determination process of determining that an abnormality has occurred when the number of consecutive defective pixels is equal to or greater than a predetermined number of consecutive pixels.
[0084]
Therefore, without providing a large circuit or software for correcting an abnormal image, even if a defective pixel is detected, if the defective pixel is not permanent, but is temporary and is of a degree that can be tolerated in practical use, it is determined that an abnormality has occurred. Without performing the determination, the image reading is continued, and it can be appropriately determined that the abnormality is abnormal when it becomes a problem in practical use, and the usability can be improved. Images can be processed.
[0085]
Further, the image reading device 1 of the present embodiment allows the specified number of pixels or the specified number of consecutive pixels to be appropriately changed. When the specified number of pixels or the specified number of continuous pixels is changed, the specified number of pixels after the change is changed. Alternatively, abnormality determination is performed based on the specified number of consecutive pixels.
[0086]
Therefore, it is possible to appropriately change the abnormality determination level according to the usage environment of the image reading apparatus 1 or the purpose of use of the user, and the usability can be further improved.
[0087]
Further, the image reading apparatus 1 of the present embodiment performs the reading of the white plate 5a a plurality of times at different line positions, and performs the abnormality determination based on the image signal obtained when the reading is performed at the line position with the fewest defective pixels. When the abnormality is not determined to be abnormal in the abnormality determination, the original is read at the line position where the number of the defective pixels is the smallest.
[0088]
Therefore, by adjusting the detection position of dust, dirt, or the like that causes black streaks that occur depending on the use environment or use condition of the image reading apparatus 1, even if the number of defective pixels is small and an abnormality is recognized, it can withstand practical use. When the state can be avoided, it can be continuously used, and the usability can be further improved.
[0089]
Further, when the image reading apparatus 1 of the present embodiment determines that the abnormality has occurred, the image reading apparatus 1 performs an abnormality notification process of notifying and outputting the abnormality, and the reference data for shading correction of the defective pixel position from which the abnormality was determined. , Or one of the correction processes for changing and correcting.
[0090]
Therefore, it is possible to make the user recognize the abnormality or to prevent the defective pixel from affecting the original read image, and to appropriately cope with the adhesion of dust and the like, thereby improving the usability. At the same time, the image quality can be improved.
[0091]
Further, when the image reading device 1 according to the present embodiment determines that an abnormality has occurred, the image reading device 1 performs an abnormality notification process or a correction process according to a selection from the operation unit.
[0092]
Therefore, it is possible to allow the user to select the abnormality notification and correction according to the purpose and form of use of the user, thereby further improving the usability and improving the image quality. it can.
[0093]
As described above, the invention made by the present inventor has been specifically described based on the preferred embodiments. However, the present invention is not limited to the above, and can be variously modified without departing from the gist thereof. Needless to say.
[0094]
【The invention's effect】
According to the image processing apparatus of the present invention, at least a document to be conveyed is irradiated with reading light from a reading unit that is stationary at a reading position, and reflected light of the reading light is imaged by a photoelectric conversion element of the reading unit. Reads the image of the document after converting it to data, and performs shading correction on the image data obtained by reading the document based on the reference data obtained by reading the white reference plate. A white plate disposed at a position irradiated with the reading light from the unit is read by the reading unit before reading the document or at a predetermined timing, and a value indicating the density of the image signal when the white plate is read is set to a predetermined value. When a defective pixel is detected by comparing the specified value with each pixel, and if the number of pixels of the defective pixel is equal to or more than a predetermined specified number of pixels, an abnormality determination process of determining that the pixel is abnormal is performed. Without providing a large circuit or software for correcting an abnormal image, even if a defective pixel is detected, if the number of defective pixels is small enough to withstand practical use, the image reading is continued without determining that the image is abnormal. As a result, it is possible to determine that an abnormality has occurred in a practically problematic state, to improve the usability and to process an image with good image quality at low cost.
[0095]
According to the image processing apparatus of the present invention, at least a document to be conveyed is irradiated with reading light from a reading unit that is stationary at a reading position, and reflected light of the reading light is imaged by a photoelectric conversion element of the reading unit. Reads the image of the original after converting it to data, and performs shading correction on the scanned image data based on the reference data acquired by reading the white reference plate. A white plate disposed at a position where the reading light from the unit is irradiated is read by the reading unit before reading the document or at a predetermined timing, and a value indicating the density of the image signal when the white plate is read is set to a predetermined value. A defective pixel is detected by comparing the specified pixel with a specified value, and when the number of consecutive defective pixels is equal to or greater than a predetermined specified number of consecutive pixels, abnormality determination processing for determining that the pixel is abnormal is performed. Therefore, without providing a large circuit or software for correcting an abnormal image, even if a defective pixel is detected, if the defective pixel is not permanent but is temporary and can be tolerated in practical use, it is regarded as abnormal. Without performing the determination, the image reading is continued, and it can be appropriately determined that the abnormality is abnormal when it becomes a problem in practical use, and the usability can be improved. Images can be processed.
[0096]
According to the image processing apparatus of the third aspect of the present invention, the specified pixel number or the specified pixel continuation number can be changed as appropriate, and when the specified pixel number or the specified pixel continuation number is changed, the specified pixel after the change is changed. Since the abnormality determination is performed based on the number of pixels or the specified number of consecutive pixels, the abnormality determination level can be appropriately changed according to the usage environment of the image processing apparatus and the purpose of use of the user, and the usability is further improved. Can be done.
[0097]
According to the image processing device of the present invention, the reading of the white plate by the reading means is performed a plurality of times at different line positions, and the abnormality determination is performed based on the image signal obtained when the reading is performed at the line position with the fewest defective pixels. In addition, when the abnormality is not determined to be abnormal in the abnormality determination, the original is read at the line position where the number of defective pixels is the smallest, so that dust and dirt causing black stripes generated due to the use environment and use condition of the image processing apparatus are obtained. By adjusting the detection position such as that described above, even if the number of defective pixels is small and an abnormality is recognized, it is possible to avoid a situation in which it can be practically used, so that it can be used continuously, and the usability is further improved. Can be improved.
[0098]
According to the image processing apparatus of the fifth aspect of the present invention, when it is determined that there is an abnormality, the abnormality notifying process of notifying and outputting the abnormality from the abnormality notifying means, and determining the position of the defective pixel from which the abnormality was determined. Since either one of the correction processing for changing and correcting the reference data of the shading correction is performed, the abnormality can be recognized by the user, or the defective pixel can be prevented from affecting the original read image. It is possible to improve the usability and to improve the image quality by appropriately coping with the adhesion of the like.
[0099]
According to the image processing apparatus of the present invention, if it is determined that the abnormality is abnormal, the abnormality notification processing or the correction processing is performed according to the selection by the selection unit that selects the abnormality notification processing and the correction processing. It is possible to allow the user to select the abnormality notification and the correction in accordance with the purpose of use and the form of use, so that the usability can be further improved and the image quality can be improved.
[Brief description of the drawings]
FIG. 1 is a schematic configuration front view of an image reading apparatus to which an embodiment of an image processing apparatus according to the present invention is applied.
FIG. 2 is a schematic front view of a main part of the image reading apparatus in FIG. 1 during a reading operation in a book mode.
FIG. 3 is a schematic front view of a main part of the image reading apparatus in FIG. 1 during a reading operation in an ADF mode.
FIG. 4 is a circuit block diagram of a main part of the image reading apparatus of FIG. 1;
FIG. 5 is a detailed circuit block diagram of the image processing unit in FIG. 4;
FIG. 6 is a more detailed circuit block configuration diagram of the image processing unit in FIG. 5;
FIG. 7 is a circuit block diagram of a defective pixel detection unit of the image reading apparatus of FIG. 1;
FIG. 8 is a diagram showing a detection image signal and a shading data (reference data) obtained by reading a white plate when dust is attached by the image reading apparatus of FIG. 1;
FIG. 9 is an operation explanatory diagram in the case where a discarded disc is read by different reading lines by the image reading apparatus of FIG. 1;
[Explanation of symbols]
1 Image reading device
2 Body case
3 Document reading table
3a Contact glass window
3b Transmission glass
4 Document holding plate
5 Document feeder
5b white board
6 SDF unit
7 Platen
8 Stepping motor
9 White reference plate
10 First running body
10a light source
10b mirror
11 Second traveling body
11a, 11b mirror
12 lenses
13 CCD
14 Stepping motor
15 Exposure scanning optical system
16 manuscripts
17 Separation roller
18, 19 Transport roller
20 CPU
21 ROM
22 RAM
23 Light source driver
24 CCD drive unit
25 Image processing unit
26 scan buffer
27 Buffer Controller
28 I / F controller
29 Motor driver
30 Motor driver
41 Analog Video Processor
42 Shading correction processing unit
43 Image Data Processing Unit
44 Timing generator
45 Binarization processing unit
51 Preamplifier circuit
52 Variable amplifier circuit
53 A / D converter
54 Black arithmetic circuit
55 Shading correction operation circuit
56 line buffers
60 defective pixel detector
61 Binarization processing unit
62 Defective pixel holding unit
63 SRAM
70 I / F controller

Claims (6)

At least a document to be conveyed is irradiated with reading light from a reading unit that is stationary at a reading position, the reflected light of the reading light is converted into image data by a photoelectric conversion element of the reading unit, and an image of the document is read. In an image processing apparatus for performing shading correction on image data obtained by reading the document based on reference data obtained by reading a reference plate, a reading light from the reading unit is irradiated when a document does not exist in a document path at the reading position. A white plate is provided at a position to be read, and the reading unit reads the white plate before reading the document or at a predetermined timing, and sets a value indicating a density of an image signal when the white plate is read to a predetermined specified value and a pixel value. Performing an abnormality determination process of detecting a defective pixel by comparing each defective pixel and determining that the defective pixel is abnormal when the number of the defective pixel is equal to or more than a predetermined specified number of pixels; The image processing apparatus according to claim. At least a document to be conveyed is irradiated with reading light from a reading unit that is stationary at a reading position, the reflected light of the reading light is converted into image data by a photoelectric conversion element of the reading unit, and an image of the document is read. In an image processing apparatus for performing shading correction on image data obtained by reading the document based on reference data obtained by reading a reference plate, a reading light from the reading unit is irradiated when a document does not exist in a document path at the reading position. A white plate is provided at a position to be read, and the reading unit reads the white plate before reading the document or at a predetermined timing, and sets a value indicating a density of an image signal when the white plate is read to a predetermined specified value and a pixel value. A defect pixel is detected by comparing each time, and when the number of consecutive defective pixels is equal to or greater than a predetermined number of consecutive pixels, an abnormality determination process of determining that the pixel is abnormal is performed. The image processing apparatus according to claim and. In the image processing apparatus, the specified pixel number or the specified pixel continuation number can be appropriately changed, and when the specified pixel number or the specified pixel continuation number is changed, the specified pixel number or the specified pixel continuation number after the change is changed. 3. The image processing apparatus according to claim 1, wherein the abnormality is determined based on the number. The image processing apparatus performs the reading of the white plate by the reading unit a plurality of times at different line positions, and performs the abnormality determination based on an image signal obtained when the reading is performed at the line position with the least number of defective pixels. 4. The image processing apparatus according to claim 1, wherein when the abnormality is not determined to be abnormal, the original is read at a line position where the number of defective pixels is the smallest. 5. The image processing apparatus includes a predetermined abnormality notification unit, and when it is determined that the abnormality has occurred, an abnormality notification process of notifying and outputting the abnormality from the abnormality notification unit, and a defective pixel serving as a source of the abnormality determination. The image processing apparatus according to any one of claims 1 to 4, wherein one of a correction process for changing and correcting the reference data of a position is performed. The image processing apparatus includes a selection unit that selects the abnormality notification process and the correction process, and performs the abnormality notification process or the correction process according to the selection by the selection unit when the abnormality is determined. The image processing apparatus according to claim 5, wherein:

Images