JP2004356666A - Original reader, image forming apparatus, and image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable the interpolation of image data of a portion where pixels are omitted between sensor units, and obtaining highly reliable original image data. <P>SOLUTION: This original reader is provided with an original reading section 13 and an original reading section 18 for reading an arbitrary original 20 to output original image data, an omitted pixel determining section 85 provided in the section 18 and reading a portion where pixels are omitted from original image data Dout2, and an omitted pixel interpolating section 86 for interpolating the original image data Dout2 in the portion where the pixels are omitted detected by the section 85. Since the original image data Dout2 of the portion where pixels are omitted between sensor units constituting the section 18 can be interpolated into finite values by this configuration, even when the section 18 is configured of a contact type image sensor 81 in which a plurality of the sensor units are juxtaposed, the highly reliable original image data Dout2 can be outputted. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a document reading apparatus, an image forming apparatus, and an image forming method suitable for a black-and-white or color digital copier, a multifunction peripheral, a facsimile apparatus, and the like that read a document by a contact image sensor attached to a document reading system. It is about.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, a digital copying machine that forms an image based on document image data obtained from a document image is often used. In this type of copying machine, a document image is read by a scanner or the like, and document image data relating to the document image is temporarily stored in an image memory. When storing the document image data in the memory, shading correction, timing control, line-to-line correction, and the like are performed.
[0003]
The document image data after these correction processes are subjected to γ correction, scaling process, spatial filter, image compression process and the like. Here, an image based on the document image data on which the image processing has been performed is formed on predetermined paper by a printer. At this time, an electrostatic latent image based on the document image data is formed on the photoconductor uniformly charged by the charging unit.
[0004]
This electrostatic latent image is developed by a developing unit. By performing such charging, exposure, and development, the toner image formed on the photoconductor is transferred to a sheet by a transfer unit. The toner image transferred onto a predetermined sheet is fixed by a fixing unit. As a result, the original image can be copied. A contact image sensor may be incorporated in such a digital copying machine.
[0005]
FIG. 13 is a perspective view showing a configuration example of a contact type image sensor 81 according to a conventional example. The contact image sensor 81 shown in FIG. 13 includes a plurality of sensor units # S1, # S2,. One sensor unit # S1 has a printed wiring board 1, a plurality of cylindrical selfoc lenses 2, and a CCD imaging device 3.
[0006]
The CCD image pickup devices 3 are provided on the printed wiring board 1 in an elongated matrix form having two to three rows in the width direction and several hundreds in the length direction. Above that, a selfoc lens 2 which is several tens of times larger than the CCD image pickup device 3 of one pixel is provided. The incident light received through the selfoc lens 2 is photoelectrically converted by a CCD image pickup device 3 constituting a light receiving unit. The selfoc lens 2 is provided in a case 4 having a plurality of openings at a predetermined position above the CCD image sensor 3. The case 4 is attached to the printed wiring board 1 so as to continuously cover the plurality of sensor units # S1, # S2,. The seam portion 5 shown in FIG. 13 is a boundary between the sensor unit # S1 and the sensor unit # S2, and forms a gap between the CCD image pickup devices 3. The selfoc lens 2 is also provided on the joint portion 5.
[0007]
14A to 14C are diagrams illustrating a configuration example and a characteristic example illustrating a problem of the contact image sensor 81, respectively. The contact type image sensor 81 shown in FIG. 14A has, for example, 16 sensor units # S1 to # S16 arranged in the main scanning direction. In the case of a sensor function for reading an A3-size original at a resolution of 600 dpi, a long image sensor 81 is used. L = about 300 mm. One sensor unit # S1 includes a CCD image pickup device 3 having about 450 pixels.
[0008]
When an image is read by the contact type image sensor 81 in which the 16 sensor units # S1 to # S16 are arranged in the main scanning direction, the image located between the sensor units has the CCD image sensor 3 present. Therefore, the image of this part cannot be read. For this reason, pixels between the sensor units are missing.
[0009]
In the contact type image sensor 81 shown in FIG. 14A, a missing pixel Pi occurs between the sensor unit # S1 and the sensor unit # S2 or between the sensor unit # S2 and the sensor unit # S3 shown in FIG. 14B. . Similarly, a missing pixel Pi occurs between the sensor unit # S15 and the sensor unit # S16. In other words, when the contact type image sensor 81 of 7200 pixels per line is configured using 16 sensor units # S1 to # S16, a total of 15 missing pixels Pi (i = 1 to 15) are generated. I do.
[0010]
The missing pixel Pi between the sensor units is caused by a gap generated due to a problem of installation accuracy of the sensor unit # S1 and the like. To remove this gap, a plurality of sensor units # S1 to # 16 and the like are continuously connected. This is very difficult with respect to the technology for forming the contact type image sensor 81 by disposing them in such a manner. However, if a large-diameter semiconductor wafer can be manufactured at low cost and a contact-type image sensor in which CCD image pickup devices 3 each having 7,200 pixels per line are provided at once, the problem of the missing pixel Pi can be solved.
[0011]
In the input-output characteristics of the contact image sensor 81 shown in FIG. 14C, the vertical axis is the output, and the horizontal axis is the input. According to the input-output characteristics, the input-output characteristics of the contact type image sensor 81 should change linearly if there is no missing pixel Pi, but the influence of the missing pixel Pi between the sensor units. As a result, the input-output characteristics become step-like, and the linearity is deteriorated.
[0012]
The number of missing pixels Pi that deteriorates the linearity of the input-output characteristics of the contact type image sensor 81 varies depending on the number of components such as the sensor unit # S1 and the like. There is one less than the number. For this reason, since the missing pixels Pi exist regularly in the main scanning direction in the document image data, the image of the missing pixels Pi can be confirmed as vertical stripes when viewed on the entire screen.
[0013]
[Problems to be solved by the invention]
By the way, according to the digital copier having the contact type image sensor 81 according to the conventional example in the scanner unit, as a means for interpolating missing pixels Pi occurring in the contact type image sensor 81, image processing such as smoothing the entire image is performed. By doing so, the partial deterioration in image quality caused by the missing pixel Pi is made inconspicuous. Therefore, there are the following problems.
[0014]
{Circle around (1)} The resolution of the entire document read by the scanner unit is reduced.
{Circle around (2)} Due to the influence of the missing pixels, the entire image becomes a full image, and the copied image is reduced only in the main scanning direction compared to the size of the original image.
(3) With the problems of (1) and (2) not being solved, the contact type image sensor 81 is applied to the scanner section, and an attempt is made to constitute a digital copier capable of reading both sides of a document simultaneously with the reduced type image sensor. In this case, a difference occurs in the document image data obtained from both sides of the document, which hinders improvement in the reliability of the scanner and the digital copying machine.
[0015]
Accordingly, the present invention has solved the above-described problems of the conventional example, and it has been made possible to improve the reproducibility of the pixel missing portion without lowering the resolution of the entire image, and to improve the reproducibility of the original image. It is an object of the present invention to provide a document reading apparatus, an image forming apparatus, and an image forming method that can match the magnification of the original.
[0016]
[Means for Solving the Problems]
In order to solve the above-described problems, a document reading apparatus according to the present invention is a device that reads an arbitrary document, and includes a document reading unit that reads an arbitrary document and outputs document image data; Detecting means for detecting a missing pixel portion from the output document image data.
[0017]
According to the document reading apparatus of the present invention, when reading an arbitrary document and outputting document image data, the document reading unit reads an arbitrary document and outputs document image data. On the premise of this, the detecting unit detects a missing pixel portion from the document image data output from the document reading unit.
[0018]
Therefore, the original image data of the pixel missing portion detected by the detecting means can be interpolated by the interpolating means, for example. The interpolation means interpolates the document image data of the missing pixel portion based on the average luminance value of the pixels before and after the missing pixel portion. As a result, the original image data of the pixel missing portion between the sensor units constituting the original reading unit can be corrected to a finite value by the interpolation process. Therefore, the original reading unit is constituted by a contact type image sensor having a plurality of the sensor units arranged in parallel. Even in this case, the reproducibility of the pixel missing portion can be improved without deteriorating the image quality of the entire image. Also, the magnification for the original image can be matched.
[0019]
An image forming apparatus according to the present invention is an apparatus that forms an image based on arbitrary document image data, a document reading device that reads an arbitrary document and outputs document image data, and an image output by the document reading device. Image forming means for forming an image based on the document image data, and the document reading apparatus has a detecting means for detecting a missing pixel portion from the document image data.
[0020]
According to the image forming apparatus of the present invention, since the original reading apparatus of the present invention is applied, a finite value is inserted into the image data of the pixel missing portion between the sensor units constituting the original reading apparatus by interpolation processing. Can be.
[0021]
Therefore, even when the original reading device is configured by a contact type image sensor in which a plurality of sensor units are arranged in parallel, the reproducibility of the pixel missing portion can be improved without lowering the image quality of the entire image. In addition, the magnification of the original image can be matched, and an image with high reliability can be formed.
[0022]
An image forming method according to the present invention is a method of forming an image based on arbitrary document image data, in which a contact image sensor is attached to a document reading system, and a document reading system to which the contact image sensor is attached is attached. An arbitrary document is read to obtain document image data, a pixel missing portion is detected from the document image data obtained here, and the document image data of the pixel missing portion detected here is interpolated. An image is formed based on the obtained document image data.
[0023]
According to the image forming method of the present invention, when an image is formed based on arbitrary document image data, even when a document reading system is configured by a contact type image sensor in which a plurality of sensor units are arranged in parallel, It is possible to improve the reproducibility of the pixel missing portion without lowering the image quality of the entire image. In addition, the magnification of the original image can be matched, and an image with high reliability can be formed.
[0024]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, an embodiment of a document reading apparatus, an image forming apparatus, and an image forming method according to the present invention will be described with reference to the drawings.
(1) First embodiment
FIG. 1 is a conceptual diagram showing a configuration example of a scanner 100 for simultaneous double-sided reading to which a document reading apparatus according to a first embodiment of the present invention is applied.
In this embodiment, when an original is read and original image data is output, the original reading unit is provided with interpolation means for interpolating original image data of a pixel missing portion detected from the original image data. The image data of a pixel missing portion between constituent sensor units can be corrected by interpolation processing, and highly reliable original image data can be obtained.
[0025]
The scanner 100 shown in FIG. 1 is an example of a document reading apparatus that reads an arbitrary document, and reads both sides of the document at the same time (double-sided reading automatic paper feed mode). The scanner 100 is applied as a document reading function of a black-and-white or color digital copying machine, a multifunction peripheral, a facsimile machine, or the like, in addition to being applied as a document reading-only machine.
[0026]
The scanner 100 includes an automatic document feeder (hereinafter, referred to as ADF) 40 and a document reading unit 50 which constitute an example of a document reading unit. The scanner 100 automatically feeds an arbitrary document and reads both sides of the document. It operates to output front and back original image data.
[0027]
The ADF 40 is attached to an upper portion of the apparatus main body, and includes a document placing portion 41, rollers 42a, 42b, rollers 43, transport rollers 44, and a paper discharge tray 46. One or a plurality of originals 20 are placed on the original placing portion 41. In this example, in the case of simultaneously reading the originals 20 on which double-side recording has been performed, the automatic double-side reading paper feed mode is selected. Of course, in addition to this mode, a one-sided reading automatic paper feeding mode is also prepared.
[0028]
Rollers 42a and 42b are provided on the downstream side of the above-mentioned original placing section 41. When the automatic double-sided reading paper feed mode is selected, the original 20 fed out of the original placing section 41 is fed to the downstream rollers 43a. Is conveyed so as to rotate in a U-shape.
[0029]
On the other hand, the first document reading section 13 is provided in the main body device, and the second document reading section 18 is provided below the mounting position of the roller 42b. The original reading unit 13 uses a reduced image sensor, and the original reading unit 18 uses a contact image sensor in which a plurality of sensor units are arranged in parallel. When the document 20 is transported by the rollers 42a and 42b, the document reading unit 18 reads the back surface of the document 20 and outputs image data of the back surface of the document.
[0030]
The document reading unit 13 reads the surface of the document 20 and outputs image data of the surface of the document when the document 20 is inverted into a U-shape by the rollers 43, for example. The image reading unit 13 has a first platen glass 51, a second platen glass 52, a light source 53, mirrors 54, 55, 56, an imaging optical unit 57, a CCD image pickup device 58, and an optical driving unit (not shown). . The document 20 read by the document reading units 18 and 13 is transported by the transport rollers 44 and discharged to a paper discharge tray 46.
[0031]
When the one-sided reading automatic paper feed mode is selected, for example, only the document reading unit 13 operates and the document reading unit 18 stops outputting. Of course, the recording surface of the document 20 is placed on the document placing portion 41 facing upward.
[0032]
FIG. 2 is a block diagram illustrating a configuration example of a control system of the scanner 100. The scanner 100 shown in FIG. 2 has first and second document reading units 13 and 18. The document reading unit 13 reads, for example, the surface of an arbitrary document 20 and outputs image data Dout1 of the document surface. The document reading unit 13 includes the reduced image sensor 3, the A / D conversion unit 32, and the shading correction unit 33.
[0033]
The reduced image sensor 31 outputs an analog image signal Sin1 of the document surface obtained by reading the surface of the document 20. An A / D converter 32 is connected to the reduced image sensor 31, and the analog image signal Sin1 is converted from analog to digital. The A / D conversion unit 32 is connected to a shading correction unit 33, and the digital image signal Din1 after the A / D conversion is subjected to shading correction processing.
[0034]
For example, the document reading unit 18 reads the back surface of the document 20 and outputs image data Dout2 of the back surface of the document. The document reading unit includes a contact image sensor 81, an A / D conversion unit 82, a shading correction unit 83, and a pixel interpolation unit 84. Note that the pixel interpolation unit 84 includes a missing pixel determination unit 85 and a missing pixel interpolation unit 86.
[0035]
The contact image sensor 81 outputs an analog image signal Sin2 of the front surface of the document obtained by reading the back surface of the document 20. An A / D converter 82 is connected to the contact type image sensor 81, and the analog image signal Sin2 is converted from analog to digital. The A / D converter 82 is connected to a shading corrector 83, which performs a shading correction process on the digital image signal Din2 after the A / D conversion.
[0036]
A missing pixel determining unit 85, which is an example of a detecting unit, is connected to the shading correcting unit 83, and detects a missing pixel portion from the original image data Din2 after the shading correction.
[0037]
The missing pixel determining unit 85 is connected to a missing pixel interpolating unit 86 which is an example of an interpolating unit, and interpolates the original image data Din2 of the pixel missing portion detected by the missing pixel determining unit 85. In this example, the missing pixel interpolating unit 86 is configured to interpolate the original image data Din2 of the pixel missing part based on the average luminance value of the pixels before and after the pixel missing part.
[0038]
Note that a delay processing unit 34 such as a buffer memory may be provided at an output stage of the document reading unit 13 in order to align output timings of the document reading unit 13 and the document reading unit 18.
[0039]
FIG. 3 is a block diagram showing an example of the internal configuration of the pixel interpolation unit 84. In this example, the lack of pixels occurring in the contact-type image sensor 81 is caused by the fact that an image corresponding to the light receiving portion coming to the joint portion 5 between the sensor units shown in FIG. It is on the street. Various methods are conceivable for the interpolation of the luminance value of such a missing pixel Pi. In this example, a test based on an actual measurement or an empirical value obtained by performing a simulation is used.
[0040]
In general, since the number of pixels of the sensor unit # S1 and the like constituting the contact type image sensor 81 is constant, it is determined whether or not a pixel between pixels is a joint portion of the sensor unit # S1 or the like. It can be determined, and its period is constant. Therefore, the missing pixel Pi with respect to the document image signal Sin2 output from the contact image sensor 81 can be found under the following conditions.
[0041]
Here, assuming that the number of pixels of the sensor unit is m, the number of sensor units constituting the close contact image sensor 81 is n, and a missing pixel Pi of one pixel occurs at a joint between the sensor units, The pixel Pi is expressed by the equation (1), that is,
Pi = (m + 1) × n (1)
Required by
[0042]
However, since the missing pixel Pi occurs between the sensor units, i is 1 to (n-1). By using these for the missing pixel detection condition, it is possible to determine where the missing pixel Pi is in the document image data Din2.
[0043]
The pixel interpolating unit 84 illustrated in FIG. 3 includes, for example, a missing pixel determining unit 85 and a missing pixel interpolating unit 86. The missing pixel determination unit 85 has a detection unit 851 and a counter 852.
[0044]
The original image data Din2 after the shading correction is input to the detection unit 851. The detector 851 detects the document image data Din2 from the shading correction circuit 83 based on a horizontal cycle signal (hereinafter, referred to as an HV signal). The HV signal is a signal that defines a period for scanning the document 20 in the line direction, that is, the main scanning direction. For example, when the HV signal rises, at the same time, it is detected whether or not the luminance value of the pixel by the CCD image pickup device at the foremost part of the first sensor unit is input, and the head of one line of the document 20 is detected. This detection process is for determining the number of pixels and the number of missing pixels Pi in the document image data Din2.
[0045]
A counter 852 is connected to the detection unit 851. When the detection unit 851 detects the head of one line of the document 20, a head detection signal (hereinafter referred to as a signal) is output from the detection unit 851 to the counter 852. The counter 852 counts the clock signal CK1 for writing to the memory using the signal a as a start signal, and generates a count output signal (hereinafter, referred to as signal b). The b signal is a signal for latching the luminance values of the pixels before and after the joint between the sensor units, and the b signal is output to the missing pixel interpolation unit 86. As a result, a missing pixel portion can be detected from the original image data Din2 after the shading correction.
[0046]
Further, the missing pixel interpolation unit 86 connected to the missing pixel determination unit 85 has two latch circuits 861 and 862, a memory unit 863, an arithmetic unit 864, and an adder 865. In the missing pixel interpolation unit 86, the luminance value of the missing pixel Pi is interpolated based on the determination information (b signal) from the missing pixel determination unit 85 and the document image data Din2. A memory unit 863 is connected to the detection unit 851, and the document image data Din2 after shading correction is sequentially written based on the clock signal CK1, and the document image data after shading correction based on the clock signal CK2 for memory reading. Din2 is sequentially read.
[0047]
The signal b output from the counter 852 is input to the latch circuits 861 and 862. The latch circuit 861 latches the luminance value of the pixel at the last end of the i-th sensor unit based on the signal b. The latch circuit 862 operates to latch the luminance value of the pixel at the foremost part of the (i + 1) th sensor unit based on the signal b.
[0048]
An arithmetic unit 864 is connected to these latch circuits 861 and 862, and the luminance value X of the pixel at the final end of the i-th sensor unit latched by the latch circuit 861 and the (i + 1) th pixel latched by the latch circuit 862 The luminance value Y of the pixel at the forefront of the second sensor unit is calculated. In the arithmetic unit 864, for example, the average value Z of the luminance value X and the luminance value Y, that is, the equation (2), that is,
Z = (X + Y) / 2 (2)
Is calculated. The average value Z is a luminance value for interpolating between the luminance value of the pixel at the final end of the i-th sensor unit and the luminance value of the pixel at the foremost part of the (i + 1) -th sensor unit.
[0049]
An adder 865 is connected to the memory unit 863 and the arithmetic unit 864. When the document image data Din2 after shading correction is sequentially read from the memory unit 863 based on the clock signal CK2, the last of the i-th sensor unit is read. The average value Z calculated by the calculator 864 is inserted between the luminance value X of the pixel at the end and the luminance value Y of the pixel at the foremost part of the (i + 1) th sensor unit. Accordingly, the missing pixel interpolating unit 86 can interpolate the luminance value of the pixel Pi in the pixel missing part based on the luminance values X and Y of the pixels before and after the pixel missing part. Can be output.
[0050]
Subsequently, an operation example of the scanner 100 will be described. 4A to 4J are time charts illustrating an operation example of the pixel interpolation unit 84. In FIG. 4, A is an HV signal, B is a clock signal CK1, C is original image data Din2, D is an a signal, E is a b signal, F is a luminance value X, G is a luminance value Y, H is a luminance value Z, I is the clock signal CK2 and J is the output value Dout2.
[0051]
In this example, it is assumed that the back side image of the original 20 is read, and the description of the operation of reading the front side image of the original 20 is omitted. That is, a case where the average value Z of the luminance values X and Y of one pixel before and after the missing pixel Pi as viewed from the main scanning direction of the document 20 is regarded as the missing pixel Pi, and the luminance value of the missing pixel Pi is interpolated. Take an example. In this way, it is possible to interpolate the luminance value Z of the pixel of the missing pixel Pi without affecting other image quality.
[0052]
Under this operating condition, the HV signal shown in FIG. 4A is input to the detection unit 851, and the original image data Din2 after shading correction shown in FIG. 4C is input to the detection unit 851. The detector 851 detects the original image data Din2 from the shading correction circuit 83 based on the HV signal. For example, at the same time when the HV signal rises, it is detected whether or not the luminance value of the pixel by the CCD image pickup device at the foremost portion of the first sensor unit is input, and the head of one line of the document 20 is detected. At this time, the signal a shown in FIG. 4D is output from the detector 851 to the counter 852. Further, original image data Din2 after shading correction is recorded in the memory unit 863 based on the clock signal CK1 shown in FIG. 4B.
[0053]
The counter 852 counts the clock signal CK1 using the signal a shown in FIG. 4D as a start signal, and generates the signal b shown in FIG. 4E. The b signal is a signal for latching the luminance values of the pixels before and after the joint between the sensor units, and the b signal is output to the missing pixel interpolation unit 86. As a result, a missing pixel portion can be detected from the original image data Din2 after the shading correction.
[0054]
The luminance value X (the luminance value of the pixel at the final end of the i-th sensor unit) X shown in FIG. 4F is latched in the latch circuit 861 to which the b signal is input. Similarly, in the latch circuit 861 to which the b signal is input, the luminance value (the luminance value Y of the pixel at the foremost part of the (i + 1) th sensor unit) shown in FIG. 4G is latched.
[0055]
The luminance value X of the pixel at the final end of the i-th sensor unit latched by the latch circuit 861, the luminance value Y of the pixel at the foremost portion of the (i + 1) -th sensor unit latched by the latch circuit 862, and Is calculated by the calculator 864 based on the above equation (2). The luminance value Z shown in FIG. 4H is output from the arithmetic unit 864 to the adder 865. The average value Z is a luminance value for interpolating between the luminance value of the pixel at the final end of the i-th sensor unit and the luminance value of the pixel at the foremost part of the (i + 1) -th sensor unit.
[0056]
Also, the original image data Din2 after the shading correction is sequentially read from the above-mentioned memory unit 863 based on the clock signal CK2 shown in FIG. 4I. At this time, the adder 865 sets the arithmetic unit 864 between the luminance value X of the pixel at the final end of the i-th sensor unit and the luminance value Y of the pixel at the foremost part of the (i + 1) -th sensor unit. Is inserted. Thereby, the missing pixel interpolating unit 86 can interpolate the luminance value of the pixel Pi in the pixel missing part based on the luminance values X and Y of the pixels before and after the pixel missing part. The document image data Dout2 including the luminance value Z of the pixel can be output.
[0057]
Subsequently, the interpolation method in the pixel interpolation unit 84 and another interpolation method will be compared and considered. 5A and 5B are diagrams showing an example of pixel interpolation by the interpolation method # 1 according to the present invention. 6A and 6B are diagrams illustrating an example of pixel interpolation by an interpolation method # 2 according to a comparative example.
[0058]
5 and 6, A is an example of the arrangement of pixels before interpolation, and B is a diagram showing an example of the arrangement of pixels after interpolation.
[0059]
According to the interpolation method # 1 shown in FIG. 5A, when a circle indicated by a dashed line is a missing pixel Pi, the missing pixel shown in FIG. 5B is obtained by averaging the luminance values X and Y of the pixels before and after the missing pixel Pi. This is a case where the luminance value Z of Pi is interpolated by the above equation (1).
[0060]
According to the interpolation method # 2 shown in FIG. 6A, when a circle indicated by a wavy line is a missing pixel Pi, the luminance value a of the pixel on the upper left of the missing pixel Pi, the luminance value b of the pixel on the upper right of the missing pixel Pi, The average value of the luminance values c and d of the left and right pixels of the missing pixel Pi, the luminance value e of the lower left pixel of the missing pixel Pi, and the luminance value f of the lower right pixel of the missing pixel Pi indicates the missing pixel Pi shown in FIG. Of the luminance value Z ′ of Expression (3), that is,
Z ′ = (a + b + c + d + e + f) / 6 (3)
This is the case where interpolation is performed by
[0061]
FIGS. 7A to 7C are diagrams for comparing an image forming example by the interpolation methods # 1 and # 2 before the interpolation on the "diagonal line" original. FIGS. 8A to 8C are diagrams for comparing an image forming example by the interpolation methods # 1 and # 2 before the interpolation relating to the "halftone dot (dot)" original. FIGS. 9A to 9C are diagrams illustrating comparison between image formation examples by the interpolation methods # 1 and # 2 before interpolation of the photograph of the "eye".
[0062]
7 to 9, A is an example of image formation based on the original image data Dout2 before interpolation read by the contact image sensor 81, and B is an image based on the original image data Dout2 after interpolation by the interpolation method # 1. FIG. 9C is a diagram illustrating an example of image formation based on the document image data Dout2 after interpolation by interpolation method # 2.
[0063]
According to the image forming example of the document 20 of the “diagonal line” before interpolation shown in FIG. 7A, it can be seen that the vertical streak is formed at the position indicated by the downward arrow. This vertical streak reflects a pixel missing portion occurring in the contact image sensor 81. That is, the image corresponding to the light receiving portion at the joint between the sensor units shown in FIG. 14A could not be read, and pixels were missing.
[0064]
On the other hand, according to the image forming example of the “diagonal line” original 20 shown in FIG. 7B after the interpolation by the interpolation method # 1 of the present invention, the vertical streak is almost formed at the position indicated by the downward arrow. I understand that there is no. This is because the luminance value Z of the missing pixel Pi shown in FIG. 5B is obtained by the interpolation method # 1 shown in FIG. 5A by the average value of the luminance values X and Y of the pixels before and after the missing pixel Pi indicated by the broken line. Is interpolated by the above equation (1).
[0065]
According to this interpolation method # 1, the luminance value Z is interpolated with respect to the missing pixel Pi using the average value of the luminance values X and Y of the preceding and succeeding pixels with respect to the main scanning direction. Therefore, in reproducing a “diagonal line” or the like, it is possible to perform interpolation such that a boundary portion (line, point, edge) is emphasized.
[0066]
According to the image forming example of the “diagonal line” original 20 shown in FIG. 7C after the interpolation by the interpolation method # 2 of the comparative example, the vertical streak is hardly formed at the position indicated by the downward arrow. It can be seen that the image of the “diagonal line” of the document 20 is thick. According to the interpolation method # 2 shown in FIG. 6A, the luminance values a and f of the pixels above and below the missing pixel Pi indicated by the dashed line, the luminance values c and d of the pixels before and after the missing pixel Pi, This is because the luminance value of the missing pixel Pi shown in FIG. 6B is interpolated by the formula (3) using the average value of the luminance values b and e of the pixels obliquely above and below the missing pixel Pi.
[0067]
According to this interpolation method # 2, since interpolation is performed using the luminance average value of a total of six pixels, that is, diagonally up and down, front and back, and up and down of the missing pixel Pi, extra pixels are subject to interpolation calculation. This means that the portion that should be interpolated into a white image takes into account the black pixels of the surrounding pixels, and interpolation is performed up to the luminance value of the extra pixels, resulting in black streaks.
[0068]
In addition, according to the image forming example of the original “dotted” document 20 shown in FIG. 8A before interpolation, it can be seen that the vertical streak is formed at the position indicated by the downward arrow. This vertical streak reflects a pixel missing portion occurring in the contact image sensor 81. That is, the image corresponding to the light receiving portion at the joint between the sensor units shown in FIG. 14A could not be read, and pixels were missing.
[0069]
On the other hand, according to the image forming example of the "halftone dot" document 20 shown in FIG. 8B after the interpolation by the interpolation method # 1 of the present invention, the vertical streak is almost formed at the position indicated by the downward arrow. I understand that there is no. This is because the luminance value Z of the missing pixel Pi shown in FIG. 5B is obtained by the interpolation method # 1 shown in FIG. 5A by the average value of the luminance values X and Y of the pixels before and after the missing pixel Pi indicated by the broken line. Is interpolated by the above equation (1).
[0070]
According to this interpolation method # 1, interpolation is performed on the missing pixel Pi using the luminance value Z, which is the average value of the luminance values X and Y of the preceding and succeeding pixels, when viewed from the main scanning direction. Therefore, in the reproduction of the "halftone dot", it has become possible to perform interpolation so as to emphasize the boundary part of the "halftone dot".
[0071]
According to the image forming example of the document 20 of “halftone dot” shown in FIG. 8C after the interpolation by the interpolation method # 2 of the comparative example, almost no vertical streak is formed at the position indicated by the downward arrow. It can be seen that the image related to the “dotted” document 20 is thick and blurred. According to the interpolation method # 2 shown in FIG. 6A, the luminance values a and f of the pixels above and below the missing pixel Pi indicated by the dashed line, the luminance values c and d of the pixels before and after the missing pixel Pi, This is because the luminance value Z of the missing pixel Pi shown in FIG. 6B is interpolated by the equation (3) using the average value of the luminance values b and e of the pixels obliquely above and below the missing pixel Pi.
[0072]
According to this interpolation method # 2, interpolation is performed using the luminance average value Z ′ of a total of six pixels, that is, diagonally up, down, front, back, and up and down of the missing pixel Pi. As a result, even if the luminance value of an extra pixel is interpolated, this effect appears as a thick and blurred halftone dot.
[0073]
Further, according to the image forming example of the photograph of the “eye” before the interpolation shown in FIG. 9A, it can be seen that the horizontal streak is formed at the position indicated by the horizontal arrow. The main scanning direction is rotated by 90 ° as compared with FIGS. 7 and 8 in consideration of the legibility of the drawing. That is, the missing pixel Pi is shown to be located in the horizontal direction.
[0074]
The horizontal streak shown in FIG. 9A reflects a pixel missing portion occurring in the contact image sensor 81. In FIG. 9A, a clear effect of missing pixels can be confirmed near the center of the photograph of the eye. That is, the image corresponding to the light receiving portion at the joint between the sensor units shown in FIG. 14A could not be read, and pixels were missing.
[0075]
On the other hand, according to the image forming example of the photograph of the “eye” shown in FIG. 9B after the interpolation by the interpolation method # 1 of the present invention, the horizontal streak is hardly formed at the position indicated by the horizontal arrow. I understand. This is because the luminance value Z of the missing pixel Pi shown in FIG. 5B is obtained by the interpolation method # 1 shown in FIG. 5A by the average value of the luminance values X and Y of the pixels before and after the missing pixel Pi indicated by the broken line. Is interpolated by the above equation (1).
[0076]
According to this interpolation method # 1, interpolation is performed on the missing pixel Pi using the luminance value Z, which is the average value of the luminance values X and Y of the preceding and succeeding pixels, when viewed from the main scanning direction. Therefore, in reproducing the photograph of the "eye", it has become possible to perform interpolation so as to emphasize the boundary portion of the photograph of the "eye". In a photographic image, unlike a line image, a boundary between lines and the like do not appear clearly, so that there is no difference between the interpolation method # 1 and the interpolation method # 2. Compared with the image forming example before interpolation shown in FIG. 9A, it is clear that the image quality is improved by interpolating the luminance value of the pixel missing part.
[0077]
As described above, according to the scanner 100 for double-sided simultaneous reading to which the original reading apparatus according to the first embodiment of the present invention is applied, when an arbitrary original 20 is read and original image data Dout2 is output, missing data is output. The pixel determination unit 85 detects a missing pixel portion from the document image data Din2 output from the shading correction unit 83. In the missing pixel interpolation unit 86, the arithmetic unit 864 calculates a value between the luminance value X of the pixel at the final end of the i-th sensor unit and the luminance value Y of the pixel at the foremost part of the (i + 1) -th sensor unit. The luminance value Z, which is the calculated average value, is inserted.
[0078]
Therefore, based on the luminance values X and Y of the pixels before and after the pixel missing portion between the sensor units constituting the contact type image sensor 81, a finite value is inserted into the luminance value Z of the pixel Pi in the pixel missing portion by interpolation. Thus, the original image data Dout2 including the luminance value Z of the pixel of the missing pixel Pi shown in FIG. 4J can be output.
[0079]
Thus, even when the contact type image sensor 81 in which a plurality of sensor units are arranged side by side constitutes the simultaneous double-sided original reading function, it is possible to improve the reproducibility of the pixel missing portion without lowering the image quality of the entire image. Become like In addition, the magnification of the original image can be made to match, and highly reliable original image data Dout2 can be output.
[0080]
(2) Second embodiment
FIG. 10 is a conceptual diagram showing a configuration example of a cross section of a digital copying machine 200 as a second embodiment according to the present invention.
In this embodiment, a digital copying machine 200 is configured as an example of an image forming apparatus. The copying machine 200 incorporates a scanner function having a contact image sensor (CIS) attached thereto, and occurs in the contact image sensor. It has a function of interpolating missing pixels. In the copying machine 200, a portion where a pixel is missing from the original image data Din2 is determined, and the reproduction of the missing pixel Pi is performed on the determined pixel missing portion by the luminance value (image information) of the peripheral pixel. Is what you do. For pixel reproduction, interpolation is performed using a luminance value Z which is an average value of luminance values of one pixel before and after when viewed from the main scanning direction.
[0081]
A digital copying machine 200 shown in FIG. 10 is an apparatus that forms an image by feeding predetermined paper. The digital copying machine 200 constitutes a multifunction machine of a direct transfer system for obtaining a monochrome image, and has an apparatus main body A. In the apparatus main body A, there are provided a control device 15, sheet feeding cassettes (sheet feeding units) 30A and 30B, an image writing unit 60, an image forming unit (image forming unit) 70, a scanner unit 100, and the like. The scanner unit 100 includes a document reading unit 13 and a document reading unit 18 and reads an arbitrary document 20 and outputs front and back document image data Dout1 and Dout2. The document reading device described in the first embodiment is used for the scanner unit 100.
[0082]
An automatic document feeder (ADF) 40 is attached to an upper portion of the apparatus main body A. Note that the ADF 40 and the first and second document reading units 13 and 18 are described in FIG. 1, and thus description thereof is omitted here. The document reading section 13 is provided with a CCD image pickup device 58 constituting a reduced image sensor. The output stage of the CCD image pickup device 58 is connected to the image processing means 21 and performs image processing of the document image data Dout1. The document image data Dout1 is output to the image forming unit 70.
[0083]
Further, the ADF 40 is provided with a document reading unit 18, and an output stage of the document reading unit 18 is also connected to the image processing unit 21, and a document after image processing of document image data Dout 2 obtained from a contact image sensor (not shown). The image data Dout2 is output to the image forming unit 70. The image forming unit 70 includes an organic photosensitive drum (hereinafter referred to as a photosensitive drum) 71, a charging unit 72, a developing unit 73, a transfer unit 74, a separating unit 75, a cleaning unit 76, a transport mechanism 77, and a fixing unit 78. .
[0084]
A charging section 72 is provided above the photosensitive drum 71, and the photosensitive drum 71 is uniformly charged in advance based on a predetermined charging potential. An image writing 60 is provided, for example, diagonally to the upper right of the photoconductor drum 71, and the photoconductor drum 71 is exposed based on the exposure potential based on the image data Din output from the image processing means 21. An electrostatic latent image is formed.
[0085]
On the right side of the photosensitive drum 71, a developing unit 73 containing toner and a carrier (developer) is provided, and the electrostatic latent image exposed by the image writing unit 60 is developed by the toner. Below the developing section 73, a registration roller 62, paper feed cassettes 30A and 30B, and the like are provided. The paper 30 accommodated in the paper feed cassettes 30A and 30B is fed by feed rollers and paper feed rollers (not shown) provided in the paper feed cassettes 30A and 30B, respectively. After that, it is conveyed under the photosensitive drum 71.
[0086]
A transfer unit 74 is provided below the photoconductor drum 71, and the toner image formed on the photoconductor drum 71 through charging, exposure, and development is transferred to the paper 30 whose conveyance timing is controlled by the registration roller 62. Is done. A separation unit 75 is provided adjacent to the transfer unit 74, and the sheet 30 on which the toner image has been transferred is separated from the photosensitive drum 71. A transport mechanism 77 is provided downstream of the separation unit 75, and a fixing unit 78 is provided at the end thereof. In the fixing section 78, the toner image transferred to the sheet 30 is fixed. A cleaning unit 76 is provided between the transport mechanism 77 and the above-described charging unit 72 and faces the photosensitive drum 71, and cleans the toner remaining on the photosensitive drum 71.
[0087]
When double-sided copying is selected in this example, an image is formed on one sheet surface (front surface), and an image is also formed on the back surface of the sheet 30 discharged from the fixing unit 78. The sheet 30 discharged from the fixing unit 78 is branched from the sheet discharge path by a branching unit 91, and is turned upside down by a reversing roller 92 and a reversing unit 93, which constitute the sheet feeding unit 23, respectively. The sheet 30 passes through the reversing conveyance path 94 and joins with a normal sheet feeding path before the sheet feeding roller 61.
[0088]
The sheet 30 that has been reversely conveyed here is again conveyed to the transfer unit 74 via the registration roller 62, and the toner image is transferred onto the other surface (back surface) of the sheet 30. The sheet 30 to which the toner image has been transferred is subjected to a fixing process by a fixing unit 78, and is sandwiched by sheet ejection rollers 95 to be ejected to a sheet ejection tray outside the apparatus. The sheet 30 on which the image formation has been completed in the above-described processing is not limited to the discharge tray, and the stapling processing and the binding processing may be performed by the finisher unit 90 in some cases.
[0089]
At the time of forming these images, the paper 30 is 52.3-63.9 kg / m ² (1000 sheets) of thin paper or 64.0-81.4 kg / m ² (1000 sheets) of plain paper or 83.0 to 130.0 kg / m ² (1000 sheets) or 150.0kg / m ² It is preferable to use a set of super thick paper of about (1000 sheets), a linear velocity of about 80 to 350 mm / sec, and environmental conditions of a temperature of about 5 to 35 ° C. and a humidity of about 15 to 85%. The thickness (paper thickness) of the paper 30 is about 0.05 to 0.15 mm.
[0090]
FIG. 11 is a block diagram showing a configuration example of a control system of the digital copying machine 200. The digital copying machine 200 shown in FIG. 11 is an apparatus that forms an image based on arbitrary document image data Dout1 and Dout2. The digital copier 200 includes a display unit 11, an operation unit 12, a communication unit 14, a control device 15, an image memory 16, an image processing unit 21, a paper supply unit 23, an image forming unit 70, and a scanner 100. The scanner 100 includes the document reading unit 13 and the document reading unit 18 described with reference to FIG.
[0091]
The original reading unit 18 includes a missing pixel determining unit 85 that detects a pixel missing portion from the original image data Din2 as described with reference to FIG. 2, and an original of the pixel missing portion detected by the missing pixel determining unit 85. A missing pixel interpolation unit 86 for interpolating the image data Din2. For example, a contact image sensor 81 having a resolution of 600 dpi and n = 16 sensor units arranged side by side is used for the document reading unit 18. For example, one sensor unit in which CCD image pickup devices of m = 450 pixels are arranged in a line is used. The missing pixel interpolating section 86 interpolates the original image data Dout2 of the missing pixel portion based on the brightness value Z which is the average value of the brightness values X and Y of the pixels before and after the missing pixel portion.
[0092]
The controller 15 is connected to the document reading units 13 and 18. The control device 15 has a ROM (Read Only Memory) 24, a RAM (Random Access Memory) 26, and a CPU (Central Processing Unit; central processing unit) 25. The ROM 24 stores system program data for controlling the entire image forming apparatus. The RAM 26 is used as a work memory, and temporarily stores, for example, control commands and the like. When the power is turned on, the CPU 25 reads out system program data from the ROM 24 to start up the system, and controls the entire image forming apparatus based on operation data D3 from the operation unit 12.
[0093]
When an image is formed based on the document image data, the display means 11 displays the image forming conditions such as the number of copies, the presence or absence of the front and back of the document, and the image forming density. The image forming conditions are displayed based on the display data D2. The operation unit 12 is operated to set a double-sided reading automatic paper feed mode of the document 20, a single-sided reading automatic paper feed mode, and the like. Of course, the operation is performed so as to select not only the mode setting but also the image forming conditions such as the number of copies, the presence / absence of the document, the image forming density, and the like. The operation data D3 obtained by selecting these image forming conditions is output to the control device 15.
[0094]
The operation means 12 constitutes an operation panel together with the display means 11. As the operation panel, a combination of a liquid crystal display (not shown) and a touch sensor panel is used. For example, when simultaneously reading the originals 20 on which double-side recording has been performed, the automatic double-sided paper feed mode is selected on the operation panel. Of course, when reading only one side of the document 20 on which double-side recording has been performed, the operation panel is operated to select the single-sided reading automatic paper feed mode. These modes are set for the scanner unit 100.
[0095]
Further, the image processing means 21 has an area discriminating unit 211 and a signal processing unit 212 for performing luminance density conversion, spatial filtering, γ correction and the like. The area determination unit 211 operates to determine a character area, an image area, and the like with respect to, for example, two-sided document image data Dout1 and Dout2 output from the scanner unit 100. The signal processing unit 212 performs image processing such as a luminance density conversion process, a spatial filter process, and a γ correction process for each image region determined by the region determination unit 211. Document image data Dout1 and Dout2 after image processing are temporarily stored in image memory 16. Document image data Dout1 and Dout2 are encoded, compressed, and stored in the image memory 16.
[0096]
The control device 15 controls input and output of the sheet cassettes 30A and 30B, the image writing unit 60, the image forming unit 70, the scanner unit 100, and the like based on at least the clock signal CK1 of the reference frequency and the operation data D3. Is made. The image forming unit 70 is an example of an image forming unit, and forms an image based on document image data Dout1 and Dout2 obtained by the scanner 100.
[0097]
For example, the image forming unit 70 reads the document image data Dout1 and Dout2 from the image memory 16 based on the image forming conditions set by the operation unit 12. The original image data Dout1 and Dout2 are decompressed and decoded by the image processing means 21. The decrypted document image data Dout1 and Dout2 are transferred from the image processing unit 21 to the image forming unit 70. In the image forming section 70, the document image data Dout1 and Dout2 are input to the image writing section 60 shown in FIG. In the image writing section 60, an electrostatic latent image is formed on the photosensitive drum 71 based on the document image data Dout1 and Dout2. The electrostatic latent image formed on the photosensitive drum 71 is developed with toner.
[0098]
In the paper feeding unit 23, the paper 30 based on the setting of the image forming condition is fed out from the paper feeding cassette 30A or the like based on the paper feeding control data D4, and the paper 30 is conveyed to the image forming unit 70. The paper feed control data D4 is output from the control device 15 to the paper feed means 30. In the image forming section 70, the toner image formed on the photosensitive drum 71 is transferred to the paper 30 and fixed. The communication unit 14 is connected to a communication line such as a LAN (Local Area Network), receives image data Din created by a personal computer or the like, and transfers the image data Din to the image forming unit 70 or the image memory 16. This is because the digital copier 200 is used as a printer.
[0099]
Subsequently, an operation example in the digital copying machine 200 will be described. FIG. 12 is a flowchart showing an operation example in the digital copying machine 200.
[0100]
In this embodiment, a case where a document reading device according to the present invention is applied to the scanner unit 100 and a finite value is inserted into the document image data Dout2 of a pixel missing portion between sensor units constituting the scanner unit 100 by interpolation processing. It is assumed. For example, a contact image sensor 81 having a resolution of 600 dpi and n = 16 sensor units arranged side by side is used for the document reading unit 18. For example, one sensor unit in which CCD image pickup devices of m = 450 pixels are arranged in a line is used. The missing pixel interpolating section 86 interpolates the original image data Dout2 of the missing pixel portion based on the brightness value Z which is the average value of the brightness values X and Y of the pixels before and after the missing pixel portion.
[0101]
With this as a processing condition, the process stands by until there is a copy request in step A1 of the flowchart shown in FIG. If there is a copy request, the process proceeds to step A2. In step A2, image forming conditions are input. At this time, the display unit 11 displays the image forming conditions such as the number of copies, whether or not to read the front and back of the document, and the image forming density. The image forming conditions are displayed on the display unit 11 based on the display data D2.
[0102]
For example, the user operates the operation unit 12 to set a double-sided reading automatic paper feed mode, a single-sided reading automatic paper feed mode, and the like of the document 20. The operation data D3 such as the image forming conditions set here is output to the control device 15. In this example, in a case where the document 20 on which both sides are recorded is simultaneously read and an image is formed on both sides of the sheet, the operation unit 11 selects the double-side reading automatic sheet feeding mode and the double-side mode. The double-sided reading automatic sheet feeding mode is set for the scanner unit 100, and the double-sided reading mode is set for the image forming unit 70, respectively.
[0103]
Then, the process proceeds to step A3, where the scanner unit 100 executes a double-sided document reading process. At this time, in the document reading unit 18, the back surface of the document 20 is read by the contact image sensor 81, and an analog image signal Sin 2 of the back surface of the document is output to the A / D converter 82. In the A / D converter 82, the analog image signal Sin2 is converted from analog to digital. The digital image signal Din2 after the A / D conversion is output from the A / D conversion unit 82 to the shading correction unit 83. In the shading correction unit 83, the digital image signal Din2 after the A / D conversion is subjected to shading correction processing.
[0104]
The digital image signal Din2 after the shading correction is output to the missing pixel determining unit 85, and a pixel missing portion is detected from the original image data Din2 after the shading correction. The document image data Din2 in which the pixel missing portion is detected is output from the missing pixel determining unit 85 to the missing pixel interpolating unit 86. The missing pixel interpolating section 86 interpolates the original image data Din2 of the pixel missing portion detected by the missing pixel determining section 85. At this time, the missing pixel interpolating unit 86 interpolates the original image data Din2 of the missing pixel based on the average luminance value Z of the pixels before and after the missing pixel.
[0105]
In this example, a contact-type image sensor 81 in which n = 16 sensor units are arranged side by side at a resolution of 600 dpi is used, and one sensor unit is a CCD image sensor having m = 450 pixels arranged in a line. is there. Therefore, if all the pixels in one line are set to 7200 pixels in the missing pixel interpolation unit 86, the missing pixels Pi (i = 1 to 15) are between the 450th and 451st pixels of P1 and the 902nd pixel of P2. Between pixel 903, pixel P3 = 1353 and pixel 1354, pixel P1 between pixel 1904 and pixel 1905, pixel P5 between pixel 2255 and pixel 2256, pixel P6 = 2706 Between the eye and the 2707th pixel, P7 = between the 3157th and 3158th pixels, P8 = between the 3608th and 3609th pixels, P9 = between the 4059th and 4060th pixels, P10 = Between the 4510th pixel and the 4511th pixel, P11 = between the 4961th pixel and the 4962th pixel, P12 = between the 5412th pixel and the 5413th pixel, and P13 = the 5863th pixel and the 5864th pixel. During, between P14 = 6314-th pixel and the 6315-th pixel, and between P15 = 6765-th pixel and the 6766-th pixel.
[0106]
At this time, between P1 = the 450th pixel and the 451st pixel, the pixel at the final end of the first sensor unit before interpolation, that is, the luminance value X of the 450th pixel, and the next second pixel The original image data Dout2 of the pixel missing portion is interpolated based on the luminance value Z which is the average value of the luminance value Y of the first pixel of the sensor unit, that is, the first pixel. In addition, between P2 = the 902nd pixel and the 903rd pixel, the pixel at the final end of the second sensor unit before interpolation, that is, the luminance value X of the 450th pixel, and the next third sensor unit The original image data Dout2 of the pixel missing portion is interpolated based on the luminance value Z which is the average value of the luminance value Y of the pixel at the foremost portion of the pixel.
[0107]
Further, between P3 = 1353th pixel and 1354th pixel, the pixel at the final end of the third sensor unit before interpolation, that is, the luminance value X of the 450th pixel, and the next fourth sensor unit The original image data Dout2 of the pixel missing portion is interpolated based on the luminance value Z which is the average value of the luminance value Y of the pixel at the foremost portion of the pixel. Interpolation processing is performed in the same manner, and between P15 = the 6765th pixel and the 6766th pixel, the pixel at the final end of the fifteenth sensor unit before interpolation, that is, the luminance value X of the 450th pixel, and The original image data Dout2 of the pixel missing portion is interpolated based on the luminance value Z which is the average value of the luminance value Y of the first pixel of the sixteenth sensor unit.
[0108]
In the document reading section 13, almost simultaneously with the document reading section 18, the surface of the document 20 is read by the reduced image sensor 31, and an analog image signal Sin 1 of the document surface is output to the A / D conversion section 32. In the A / D converter 32, the analog image signal Sin1 is converted from analog to digital. The digital image signal Din1 after the A / D conversion is output from the A / D conversion unit 32 to the shading correction unit 33. In the shading correction section 33, the digital image signal Din1 after the A / D conversion is subjected to shading correction processing. The output timings of the document reading unit 13 and the document reading unit 18 are aligned by a delay processing unit 34 such as a buffer memory provided at an output stage of the document reading unit 13.
[0109]
Then, the process proceeds to step A4, where the document image data Dout1 and Dout2 are stored in the image memory 16. At this time, the image processing unit 21 determines a character area, an image area, and the like with respect to the document image data Dout1 and Dout2 on both sides, and performs a brightness / density conversion processing, a spatial filter processing, a γ correction for each image area determined here. Image processing such as processing is performed. The original image data Dout1 and Dout2 after the image processing are encoded, compressed, and temporarily stored in the image memory 16.
[0110]
Then, the process proceeds to step A5 to start the sheet feeding process. At this time, the paper supply unit 23 feeds out the paper 30 based on the setting of the image forming condition from the paper supply cassette 30A or the like based on the paper supply control data D4, and conveys the paper 30 toward the image forming unit 70. .
[0111]
Then, the process proceeds to step A 6, where the document image data Dout 1 and Dout 2 are read from the image memory 16 and set in the image forming unit 70. At this time, the document image data Dout1 and Dout2 are read from the image memory 16 based on the image forming conditions previously set by the operation means 12. The original image data Dout1 and Dout2 are decompressed and decoded by the image processing means 21. The decrypted document image data Dout1 and Dout2 are transferred from the image processing unit 21 to the image forming unit 70. In the image forming section 70, the document image data Dout1 and Dout2 are input to the image writing section 60 shown in FIG.
[0112]
Thereafter, the process proceeds to step A7, and in the image forming unit 70, after the photosensitive drum 71 is charged to a predetermined potential, the image writing unit 60 forms an electrostatic latent image based on the document image data Dout1 and Dout2. . The electrostatic latent image formed on the photosensitive drum 71 is developed by the developing unit 73 with toner. The toner image formed on the photosensitive drum 71 is transferred to and fixed on the sheet 30 previously fed from the sheet feeding cassette 30A.
[0113]
In this example, since double-sided copying is selected, when an image is formed on one side (front side) of the sheet, the image is also formed on the back side of the sheet 30 discharged from the fixing unit 78. The sheet 30 discharged from the fixing unit 78 is branched from the sheet discharge path by a branching unit 91, and is turned upside down by a lower reversing roller 92 and a reversing unit 93, which constitute the paper feeding unit 23, and is conveyed reversely. The sheet passes through the path 94 and joins with the normal sheet feeding path at the sheet feeding roller 61.
[0114]
The sheet 30 that has been reversely conveyed here is again conveyed to the transfer unit 74 via the registration roller 62, and the toner image is transferred onto the other surface (back surface) of the sheet 30. The sheet 30 to which the toner image has been transferred is subjected to a fixing process by a fixing unit 78, and is sandwiched by sheet ejection rollers 95 to be ejected to a sheet ejection tray outside the apparatus. The sheet 30 on which the image formation has been completed in the above-described processing is not limited to the discharge tray, and the stapling processing and the binding processing may be performed by the finisher unit 90 in some cases.
[0115]
Then, in step A8, the control device 15 determines whether or not all the preset number of copies have been formed. If all copies have not been formed, the process returns to step A5, where the sheet is fed from the sheet cassette 30A and the like, and the document image data Dout1 and Dout2 are set in the image forming unit 70 in step A6. Thereafter, in step A7, an image is formed on the sheet 30 based on the document image data Dout1 and Dout2.
[0116]
If all the predetermined number of copies have been formed in step A8, the process proceeds to step A9 to check whether or not to end the copy process. If the copy process is not to be terminated, power save information is detected, and the process returns to step A1 to wait for a copy request. When the copy processing is to be ended, power control information and the like are detected, and the control processing ends.
[0117]
As described above, according to the digital copying machine and the image forming method according to the second embodiment of the present invention, the scanner 100 according to the present invention is applied. With respect to the original image data Dout2 of the missing pixels P1 to P15, the missing pixel interpolating unit 86 determines that the position between the 450th pixel and the 451st pixel is 450 pixels at the final end of the first sensor unit before interpolation. The original image data Dout2 of the missing pixel portion is interpolated based on the luminance value X of the eye and the luminance value Z which is the average value of the luminance value Y of the first pixel at the foremost portion of the next second sensor unit. Is made.
[0118]
In addition, between P2 = the 902nd pixel and the 903rd pixel, the luminance value X of the 450th pixel at the final end of the second sensor unit before the interpolation, and the leading edge of the next third sensor unit. The original image data Dout2 of the pixel missing portion is interpolated based on the luminance value Z which is the average value of the luminance values Y of the first pixel.
[0119]
Further, between P3 = 1353th pixel and 1354th pixel, the luminance value X of the 450th pixel at the final end of the third sensor unit before the interpolation and the foremost portion of the next fourth sensor unit. The original image data Dout2 of the pixel missing portion is interpolated based on the luminance value Z which is the average value of the luminance values Y of the first pixel. Interpolation is performed in the same manner, and between P15 = 6765th pixel and 6766th pixel, the luminance value X of the 450th pixel at the final end of the 15th sensor unit before interpolation and the next 16th pixel The original image data Dout2 of the pixel missing portion is interpolated based on the luminance value Z which is the average value of the luminance value Y of the first pixel at the foremost portion of the sensor unit.
[0120]
Therefore, it is possible to prevent a decrease in reproducibility with respect to the original image due to a missing pixel caused by the contact type image sensor 81. Also, since image processing is not performed on images other than the missing pixels, it is possible to perform high-precision interpolation on the original image without deteriorating the image quality of the entire image as in the conventional method, Highly reproducible copying can be performed.
[0121]
【The invention's effect】
As described above, according to the document reading apparatus of the present invention, when reading an arbitrary document and outputting document image data, the document image data of the pixel missing portion detected from the document image data is output. It is provided with interpolation means for performing interpolation.
[0122]
With this configuration, the image data of the pixel missing portion between the sensor units constituting the document reading unit can be corrected by the interpolation process. Therefore, this is a case where the document reading unit is configured by a contact type image sensor in which a plurality of the sensor units are arranged side by side. However, the reproducibility of the pixel missing portion can be improved without lowering the image quality of the entire image. Also, the magnification of the original image can be made to match, and highly reliable original image data can be output.
[0123]
According to the image forming apparatus of the present invention, since the original reading apparatus of the present invention is applied, a finite value is inserted into the image data of the pixel missing portion between the sensor units constituting the original reading apparatus by interpolation processing. Can be.
[0124]
With this configuration, even when a document reading apparatus is configured by a contact type image sensor in which a plurality of sensor units are arranged in parallel, the reproducibility of a pixel missing portion can be improved without deteriorating the image quality of the entire image. Become. In addition, the magnification of the original image can be matched, and an image with high reliability can be formed.
[0125]
According to the image forming method of the present invention, when an image is formed based on arbitrary document image data, the contact image sensor is attached to the document reading system, and the document reading system to which the contact image sensor is attached is used. An arbitrary document is read to obtain document image data, a pixel missing portion is detected from the document image data acquired here, and the document image data of the pixel missing portion detected here is interpolated. An image is formed based on the obtained document image data.
[0126]
With this configuration, even when a document reading system is configured by a contact type image sensor in which a plurality of sensor units are arranged side by side, the reproducibility of a pixel missing portion can be improved without lowering the image quality of the entire image. . In addition, the magnification of the original image can be matched, and an image with high reliability can be formed.
[0127]
INDUSTRIAL APPLICABILITY The present invention is extremely suitable when applied to a black-and-white and color digital copier, a multifunction peripheral, a facsimile machine, and the like for reading a document by a contact image sensor attached to a document reading system.
[Brief description of the drawings]
FIG. 1 is a conceptual diagram illustrating a configuration example of a scanner 100 to which a document reading device according to a first embodiment of the invention is applied.
FIG. 2 is a block diagram illustrating a configuration example of a control system of the scanner 100.
FIG. 3 is a block diagram illustrating an example of an internal configuration of a pixel interpolation unit 84.
FIG. 4 is a time chart illustrating an operation example of the pixel interpolation unit 84;
FIGS. 5A and 5B are diagrams showing an example of pixel interpolation by an interpolation method # 1 according to the present invention.
FIGS. 6A and 6B are diagrams illustrating an example of pixel interpolation by an interpolation method # 2 according to a comparative example.
FIGS. 7A to 7C are diagrams showing examples of image formation (oblique lines) by interpolation methods # 1 and # 2 before interpolation.
8A to 8C are diagrams showing examples of image formation (halftone dots) by interpolation methods # 1 and # 2 before interpolation.
FIGS. 9A to 9C are diagrams showing image formation examples (photographs of eyes) by interpolation methods # 1 and # 2 before interpolation.
FIG. 10 is a conceptual diagram showing a configuration example of a cross section of a digital copying machine 200 according to a second embodiment of the present invention.
FIG. 11 is a block diagram illustrating a configuration example of a control system of the digital copying machine 200.
FIG. 12 is a flowchart illustrating an operation example of the digital copying machine 200.
FIG. 13 is a perspective view illustrating a configuration example of a contact image sensor 81 according to a conventional example.
14A to 14C are diagrams illustrating a configuration example and a characteristic example illustrating a problem of the contact image sensor 81, respectively.
[Explanation of symbols]
13 First document reading unit (document reading means)
15 Control device
18. Second document reading unit (document reading means)
40 Automatic Document Feeder (ADF)
60 Image writing unit
70 Image Forming Unit (Image Forming Means)
81 Contact Image Sensor
84 pixel interpolation unit
85 Missing pixel determination unit (detection means)
86 Missing Pixel Interpolator (Interpolator)
100 scanner (document reading device)
200 Digital Copier
A device body

Claims (10)

A device for reading an original;
Document reading means for reading the arbitrary document and outputting document image data;
A document reading device comprising: a detection unit configured to detect a pixel missing portion from the document image data output from the document reading unit. 2. The original reading apparatus according to claim 1, further comprising an interpolating unit that interpolates the original image data of the pixel missing portion detected by the detecting unit. The interpolation means,
3. The document reading apparatus according to claim 1, wherein the document image data of the pixel missing portion is interpolated based on a luminance average value of pixels before and after the pixel missing portion. 4. The document reading apparatus according to claim 1, wherein the document reading unit uses a contact type image sensor in which a plurality of sensor units are arranged in a line. An apparatus for forming an image based on arbitrary document image data,
A document reading device that reads an arbitrary document and outputs the document image data;
Image forming means for forming an image based on document image data output by the document reading device,
The document reading device,
An image forming apparatus comprising: a detection unit that detects a missing pixel portion from the document image data. 6. The image forming apparatus according to claim 5, further comprising an interpolating unit that interpolates the original image data of the pixel missing portion detected by the detecting unit. The interpolation means,
7. The image forming apparatus according to claim 6, wherein the original image data of the pixel missing portion is interpolated based on a luminance average value of pixels before and after the pixel missing portion. The image forming apparatus according to claim 5, wherein a contact image sensor having a plurality of sensor units arranged side by side is used as the document reading device. The original reading device is provided with a contact type image sensor in which a plurality of sensor units that read one surface of the original are arranged in parallel,
The image forming apparatus according to claim 5, wherein a reduction-type sensor that simultaneously reads the other surface of the document is attached to the image forming unit. A method of forming an image based on arbitrary document image data,
Attach the contact type image sensor to the document reading system,
A document reading system to which the contact type image sensor is attached reads any document to obtain document image data,
Detecting a pixel missing portion from the obtained document image data,
Interpolate the document image data of the detected pixel missing portion,
An image forming method, wherein an image is formed based on the interpolated document image data.

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