JP2003032490A - Image processing device - Google Patents

Abstract

(57) [Summary] (With correction) [PROBLEMS] To provide an image processing apparatus for correcting an output abnormality caused by a stain on a reference white plate and a stain on a contact glass surface, which cause white stripes and black stripes. SOLUTION: A frame memory for temporarily storing one frame of data of read image data, and image data to be corrected or defect data are determined depending on the type of the stored data, and each of them is determined. Data switching means 102 for switching to the processing step, defective pixel detecting means 103 for detecting defective pixels, defective pixel holding means for holding defective pixel data, and image data coming from the data switching means and held in defective pixel holding means 104 Data verifying means 105 for comparing the defective pixel data set and determining whether the image data is data to be corrected.
And the image information detected by the defective pixel detection means,
A correction unit 106 that performs matrix processing using peripheral pixels to correct defective pixels is provided, and performs a series of processing for each of R, G, and B.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing apparatus for performing various kinds of image processing on image data read by an image reading apparatus, and more particularly to stains on a reference white plate and contact glass that cause white stripes and black stripes. The present invention relates to an image processing apparatus having a function of correcting an output abnormality due to dirt on a surface.

[0002]

2. Description of the Related Art Japanese Unexamined Patent Publication (Kokai) No. 10-294870 relates to an image processing apparatus having a function of correcting an output abnormality due to a stain on a reference white plate and a stain on a contact glass surface which causes white stripes and black stripes. The publication discloses a technique of compensating for the lack of pixel information caused by dust on the optical path of the reading system by using information of adjacent pixel data.

[0003]

In the above-mentioned prior art, the missing portion is detected based on the information in the main scanning direction and is corrected by using the density information of the adjacent pixels. However, only the information in the main scanning direction is used. When the correction is performed, there is a problem that the continuity of the corrected location in the sub-scanning direction is lost in the image having a high correlation in the sub-scanning direction. Further, if the missing portion is detected in two dimensions and used for correction, it is possible to grasp the portion to be corrected in both the main scanning direction and the sub scanning direction, so that it is particularly effective in protecting the continuity in the sub scanning direction. However, the conventional technique has a problem that the sub-scanning side information is not considered at all, and further, there is a problem that the R, G, B color scanner is not considered.

An object of the present invention is to solve the above-mentioned problems of the prior art. Specifically, it is caused by the stain on the reference white plate and the stain on the contact glass surface, which causes white stripes and black stripes. An object is to provide an image processing device that corrects an output abnormality.

[0005]

In order to solve the above-mentioned problems, according to the invention of claim 1, in an image processing apparatus for performing various image processing on image data read by an image reading apparatus, A frame memory that holds all data of one frame; data switching means that determines whether image data or defect data to be corrected according to the type of data stored in the frame memory and switches to each processing step; Defective pixel detecting means for detecting a defective pixel of image information; defective pixel holding means for holding defective pixel data detected by the defective pixel detecting means;
By the defective pixel detecting means and the data verifying means for comparing the image data coming from the data switching means with the defective pixel data held in the defective pixel holding means to determine whether the image data is data to be corrected. The image information of the pixel at the detected position is matrix-processed by using the peripheral pixels of the defective pixel position, and a correction means for correcting the image information of the defective pixel is provided, and the data is once stored in the frame memory to perform a series of processing. The most main feature is an image processing device that performs R, G, and B respectively.

According to a second aspect of the present invention, the correction means stores at least R, G, B stored in a frame memory.
A main feature of the image processing apparatus according to claim 1 is that, for an image in another frame unit, color dust is detected by raising and lowering an image level to correct the image in frame units.

According to a third aspect of the present invention, the correcting means stores at least R, G, B stored in the frame memory.
A main feature of the image processing apparatus according to claim 1 is that, with respect to an image in a different frame unit, dust is detected by bs for detecting an edge for each of R, G, and B, and correction is performed for each frame.

According to a fourth aspect of the present invention, the correction means stores at least R, G, B stored in the frame memory.
Threshold values can be set to R, G, and
An image processing apparatus according to claim 1, wherein the image processing apparatus is set for each B, detects dust, and corrects in frame units.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a block diagram of the image reading apparatus. As a large configuration, a reading device main body 1, a document feeding device 2, and a document reading table 3 are provided, and thus an image scanner is configured.

Inside the reading apparatus main body 1, a first traveling body 4 having a light source 4a composed of a xenon lamp or a fluorescent lamp and a mirror 4b, and a second traveling body having mirrors 5a and 5b. 5, a lens 6, a one-dimensional photoelectric conversion element (a CCD is used in this example) 7, first and second traveling bodies 4,
An exposure scanning optical system 9 including a stepping motor 8 that drives 5 is provided. Note that the description of the lower configuration of the exposure scanning optical system 9 will be omitted.

Further, the document feeder 2 includes an SDF (sheet document feeder, the same applies hereinafter) unit 10,
A document table 11 is provided. A stepping motor 12 is provided in the SDF unit 10. Further, an original pressing plate 14 is rotatably attached to the upper part of the original reading table 3, and the original 13 is attached to the original pressing plate 1.
Set under 4. A white reference plate 15 for shading correction is arranged at the end of the document reading table 3.

FIG. 2 is an overall control block diagram of the image reading apparatus. 3 is a block diagram of the document reading unit in the book mode, and FIG. 4 is a block diagram of the document reading unit in the SDF mode. The image reading apparatus shown in FIG. 2 includes a light source 4a, a CCD 7,
The stepping motors 8 and 12, the CPU 16, the light source driver 17, the CCD driving unit 18, the image processing unit 19, the motor drivers 20 and 28, the scan buffer 25, the I / F controller 26, and the buffer controller 27 are provided.

The original reading mode includes a book mode in which image data is read using an original reading table 3 as shown in FIG. 3 and an image data reading using an original feeding device 2 as shown in FIG. There is an SDF mode to perform. Therefore, first, the basic operation of reading image data in the book mode as shown in FIG. 3 will be described.

After the original 13 is set on the original reading table 3 below the original pressing plate 14, the CPU 16 causes the light source driver 17 to operate.
To turn on the light source 4a. Next, the white reference plate 15 is read by the CCD 7 driven by the CCD driving unit 18, and analog / digital conversion is performed by an A / D converter (not shown) in the image processing unit 19 for shading correction of the image data. It is stored in a RAM (not shown) in the image processing unit 19 as reference data. The CPU 16 drives the motor driver (driving device) 20 to operate the stepping motor 8, whereby the first traveling body 4 is driven.
Moves in a certain direction of the document 13. The image data of the document 13 is photoelectrically converted by the CCD 7 as the first traveling body 4 scans the document surface at a constant speed.

FIG. 5 is a block diagram showing the most basic configuration of the image processing section 19 shown in FIG. The image processing unit 19 shown in FIG. 5 includes an analog video processing unit 21, a shading correction processing unit 22, an image data processing unit 23, and a binarization processing unit 24. The analog video signal a photoelectrically converted by the CCD 7 is subjected to digital conversion processing by the analog video processing unit 21, and then shading correction processing and various image data processing are performed by the shading correction processing unit 22 and the image data processing unit 23, respectively. After performing the above, if the binary image is desired, the binarization processing unit 24 creates the binarized data b. When multi-valued data is desired, it is sent to the subsequent stage as 8-bit data. After that, the binarized data b or the multivalued data is sequentially stored in the scan buffer 25 shown in FIG.

Returning to FIG. 2 again, the I / F controller 26
Control to output the data in the scan buffer 25 to an external device such as a host computer (not shown). The buffer controller 27 uses the scan buffer 2
Input / output management of the image data to and from 5.

Next, the basic operation of reading image data in the SDF mode as shown in FIG. 4 will be described. Also in this case, first, after the white reference plate 15 is read, the CPU 16 drives the stepping motor 12 with the motor driver (driving device) 28, so that the document table 1
The document 13 set to 1 is conveyed by the separation roller 29 and the conveyance roller 30 to the predetermined reading position of the first traveling body 4. At this time, the document 13 is conveyed at a constant speed, and the first traveling body 4 reads the image data on the document surface with the CCD 7 while it is stopped.

Thereafter, the same processing as in the book mode is performed,
The binary or multi-valued image data is stored in the scan buffer 25 and sent to a host computer (not shown) or the like via the I / F controller 26.

FIG. 6 is a block diagram showing the image processing section 19 shown in FIG. 5 in more detail. The analog video processing unit 21 shown in FIG. 5 includes a preamplifier circuit 31 and a variable amplifier circuit 32. The shading correction processing unit 22 also includes an A / D converter 33, a black calculation circuit 34, a shading correction calculation circuit 35, and a line buffer 36. Original 1 on original reading table 3 with light source 4A
The reflected light irradiating 3 is condensed by the lens 6 through the shading adjusting plate 37, and imaged on the CCD 7.

Incidentally, in FIG. 6, a mirror for folding back the reflected light is omitted for simplification of description. The shading adjustment plate 37 plays a role of adjusting the light amount for eliminating the difference in the reflected light amount between the central portion and the end portion of the CCD 7. This is too much CCD in the shading calculation process.
If there is too much difference in the amount of reflected light between the central portion and the end portion, only a calculation result including distortion is likely to be obtained, so this is for performing shading calculation processing after eliminating the difference in reflected light amount in advance.

FIG. 7 is a block diagram showing the overall arrangement of an image processing apparatus according to an embodiment of the present invention. A scanner device 100 including an image reading device having a document feeding unit that feeds a document under constant control and a photoelectric conversion unit that receives reflected light from a document surface illuminated by a light source at a fixed position and converts it into digital data. The image processing apparatus 110 is connected in the subsequent stage.

The configuration of the image processing apparatus will be described below together with its operation. Image data obtained by previously scanning a white plate or the like coming from the scanner device 100, defective pixel data, and image data R, G, B are once stored in the frame memory 10.
The 1R, 101G, and 101B buffers one frame for each of R, G, and B, and the defective pixel data has its data flow switched by the data switching unit 102, and the prescan image data is sent to the defective pixel detection unit 103.

Similarly, the image data is switched in the data flow by the data switching unit 102, and the data detection unit 1
The image data is sent to 05. In the defective pixel detection unit 103, since the sent prescan data holds information on a frame-by-frame basis, a matrix is formed using prescan data including information in the sub-scanning direction, and defects are formed from the formed matrix. Detect pixels. Defective pixel holding unit 104 holds defective pixel data that also includes information in the sub-scanning direction in a matrix.

The held defective pixel data is synchronized with the image data transferred to the data verification unit 105 at an arbitrary timing and transferred to the data verification unit 105. The image data transferred to the data verification unit 105 is referred to the position of the defective pixel of the defective pixel data, and is collated with the defective pixel data using a matrix. If there is data at the same position as the defective pixel data as a result of collation, the information is transferred to the correction unit 106.

For example, a defective pixel (when the defective pixel is black)
When the position is solid black, it can be seen from the matrix that the peripheral pixels have the same value. Therefore, the result of the image is the same whether or not that part is corrected, so the correction unit 106
Does not transfer information to. Matrix processing is performed on the image data and the defective pixel data transferred to the correction unit 106 to correct the defective pixel.

FIG. 8 is an explanatory diagram of a defective pixel detection method using level up / down. When the reflected light from the surface of the original such as a white plate is previously received at a fixed position, the level of the reflected light is uniform without dust. On the surface of the original such as white plate,
Or if there is dust adhering to the glass surface, if it is colored dust, the level of the reflected light will be reduced only at the dust part, and the one with higher reflectance than white like glass scraps is the original surface such as white plate. Alternatively, when the light adheres to the glass surface, the level of the reflected light is increased only in the dust portion. This level of up and down information is digitized. As a result, it is possible to provide an image processing apparatus capable of detecting defective pixels and capable of correcting a vertical stripe image generated at the time of reading an original due to the defective pixels in a sufficient range.

[0027]

According to the first aspect of the present invention, in the image processing apparatus for performing various image processing on the image data read by the image reading apparatus, a frame for temporarily holding all data of one frame A memory and a data switching unit that determines whether to be correction target image data or defective data according to the type of data stored in the frame memory and switches to each processing step, and defective pixel detection for detecting a defective pixel of image information Means, defective pixel holding means for holding the defective pixel data detected by the defective pixel detecting means, image data from the data switching means and defective pixel data held in the defective pixel holding means are compared, and image data Data verification means for determining whether or not the data is to be corrected, and the position detected by the defective pixel detection means. The image information of the pixels in the pixel is matrix-processed by using the peripheral pixels of the defective pixel position, and a correction means for correcting the image information of the defective pixel is provided, and the data is once stored in the frame memory to perform a series of R / G processing. By performing the operation for each of B, the image data of a plurality of lines is temporarily stored, the influence of noise is mitigated, and the invalid pixels due to dust or the like are accurately detected, and the vertical black stripes or the vertical black lines due to the invalid pixels are detected based on the detection result. It is possible to provide an image processing device that corrects color lines in a sufficient range. In addition, the position of a defective (missing) pixel is accurately detected by blocking the reflected light from the document surface due to dust or the like, and based on the detection result, the missing pixel is referred to in the surrounding normal pixels, and the defective pixel is detected in the sub-scanning direction. It is possible to provide an image processing apparatus that performs correction without impairing image continuity.

According to the second aspect of the invention, the reflected light is blocked from the document surface by dust or the like, so that the document surface, which should have been at a uniform level, disappears at a uniform level, in other words, the level drops. Provided is an image processing apparatus which detects that color dust is present in that portion, holds one frame as a defective pixel, and compares the defective pixel data with image data to correct the image continuity in the sub-scanning direction without impairing it. can do.

According to the third aspect of the invention, after the read data of the white reference plate is stored once in the frame memory, the edge is detected for each of R, G and B of the image data stored in the frame memory. By doing so, an image processing apparatus that recognizes an edge portion as defective data and holds it by the defective pixel holding means, compares the defective pixel data with the image data, and corrects the image continuity in the sub-scanning direction without impairing Can be provided.

According to the invention of claim 4, the image data stored in the frame memory is stored by storing the read data of the white reference plate for one frame in the frame memory and then using a threshold value set arbitrarily. It is possible to provide an image processing apparatus which detects defective data of data, holds it by the defective pixel holding means, compares it with defective pixel data and image data, and corrects it without impairing image continuity in the sub-scanning direction.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an image reading apparatus.

FIG. 2 is an overall control block diagram of the image reading apparatus.

FIG. 3 is a configuration diagram of a document reading unit in a book mode.

FIG. 4 is a configuration diagram of a document reading unit in an SDF mode.

5 is a block diagram showing the most basic configuration of the image processing unit shown in FIG.

FIG. 6 is a block diagram showing the image processing unit shown in FIG. 5 in more detail.

FIG. 7 is a block diagram showing an overall configuration of an image processing apparatus according to an embodiment of the present invention.

FIG. 8 is an explanatory diagram of a defective pixel detection method using level up / down.

[Explanation of symbols]

101 frame memory 102 data switching unit (data switching means) 103 defective pixel detector (defective pixel detector) 104 defective pixel holding unit (defective pixel holding means) 105 data verification unit (data verification means) 106 correction unit (correction means) 110 image processing device

Claims (4)

[Claims] 1. An image processing apparatus for performing various image processing on image data read by an image reading apparatus, wherein a frame memory temporarily holds all data of one frame and data stored in the frame memory. Judge whether the image data or the defect data to be corrected depends on the type of
From the data switching means, the data switching means for switching to each processing step, the defective pixel detecting means for detecting defective pixels in the image information, the defective pixel holding means for holding the defective pixel data detected by the defective pixel detecting means, and the data switching means. Data verification means for comparing the received image data with the defective pixel data held in the defective pixel holding means to determine whether the image data is data to be corrected, and the position detected by the defective pixel detection means. The image information of the pixel in the matrix is subjected to a matrix process using peripheral pixels around the defective pixel position, and a correction unit for correcting the image information of the defective pixel is provided. An image processing device characterized by performing each of B. 2. The correction means detects color dust by increasing / decreasing an image level in at least an image in R, G, and B frame units stored in a frame memory and corrects in frame units. The image processing apparatus according to claim 1, wherein: 3. The correcting unit detects dust by detecting edges for each of R, G, and B stored in at least a frame memory for each frame of R, G, and B, and detects dust to detect each of the frames. The image processing apparatus according to claim 1, wherein the correction is performed on the image processing apparatus. 4. The correction unit arbitrarily sets a threshold value for each of R, G, and B frames stored in the frame memory for each R, G, and B frame unit, detects dust, and detects a frame. The image processing apparatus according to claim 1, wherein correction is performed in units.