JP5786585B2 - Image reading apparatus and program - Google Patents

Description

  The present invention relates to an image reading apparatus and a program.

  Japanese Patent Application Laid-Open No. 2005-228561 discloses a color image input device that decomposes and inputs a color image into R, G, and B pixel data corresponding to each CCD sensor by a plurality of CCD sensors arranged in parallel in the sub-scanning direction and having different spectral sensitivities. A re-sampling unit that interpolates and re-samples the input image data, and calculates a correlation function between the interpolated image data of any one color of the re-sampling unit and the interpolated image data of the other color, A color image comprising: a calculated correlation value calculating means for calculating a peak value of a correlation function of one read line, a peak value position (interpolated data address value), and a total value. An input device is disclosed.

JP-A-8-139949

  An object of the present invention is to provide an image reading apparatus and a program for correcting a color shift between different achromatic regions with high accuracy.

  In order to solve the above-mentioned problem, at least one of a recording medium on which an image is recorded and a light source that irradiates light to an image recording area including the image is arranged in a predetermined direction. A moving means for relative movement and a plurality of light receiving elements with different spectral sensitivities arranged in a state shifted in the predetermined direction are provided in units of one pixel, and light is applied to the image recording area during the relative movement by the moving means. The light reflected by the image recording area is received by the plurality of light receiving elements to generate an image signal corresponding to each received light amount, and the image based on the image signal generated by the generating means Detection means for detecting a boundary area between different achromatic areas in the recording area, and before output from each of the plurality of light receiving elements corresponding to pixels existing in the boundary area detected by the detection means A specifying unit that identifies a pixel in which color misregistration occurs in the boundary region based on an image signal, and a region in which the boundary region detected by the detection unit is changing from a white region to a black region by the specifying unit. Of the image signals corresponding to each of the plurality of light receiving elements corresponding to the specified pixel, when the image signal having the maximum signal level is to be corrected, the image signal and the image signal are generated before the image signal. The color shift is corrected by interpolating the corresponding image signal between two points, and the minimum signal level among the image signals corresponding to each of the plurality of light receiving elements corresponding to the pixels specified by the specifying means When the image signal having the image signal is a correction target, the image signal and the corresponding image signal generated after the image signal are interpolated between two points to thereby eliminate the color shift. And correcting means for correcting, and configured to include.

  The image reading apparatus according to claim 1 is the same as the invention according to claim 2, wherein the correction unit is further in the middle of changing the boundary region detected by the detection unit from a black region to a white region. When an image signal having the maximum signal level among the image signals corresponding to each of the plurality of light receiving elements corresponding to the pixels specified by the specifying unit is corrected, the image signal and the image signal The image signal corresponding to each of the plurality of light receiving elements corresponding to the pixels specified by the specifying means is corrected by interpolating between the corresponding image signals generated later than the two points to correct the color shift. If the image signal having the minimum signal level is to be corrected, the color is obtained by interpolating the image signal and the corresponding image signal generated before the image signal between two points. It was assumed to correct the record.

  On the other hand, in order to solve the above-mentioned problem, at least one of a recording medium on which an image is recorded and a light source that irradiates light to an image recording area including the image is predetermined. A moving unit that relatively moves in a direction and a plurality of light receiving elements having different spectral sensitivities arranged in a state shifted in the predetermined direction in units of pixels, and light is emitted to the image recording area during the relative movement by the moving unit. Is generated on the basis of the image signal generated by the generation unit and the generation unit that receives the light reflected by the image recording area and generates an image signal corresponding to each received light amount. Detection means for detecting a boundary area between different achromatic areas in the image recording area, and output from each of the plurality of light receiving elements corresponding to pixels existing in the boundary area detected by the detection means. Identifying means for identifying a pixel in which a color shift has occurred in the boundary region based on the image signal, and identifying the region where the boundary region detected by the detecting unit is changing from a black region to a white region. When an image signal having the maximum signal level among the image signals corresponding to each of the plurality of light receiving elements corresponding to the pixels specified by the means is to be corrected, the image signal is generated after the image signal and the image signal. The color shift is corrected by interpolating between the corresponding image signals at two points, and the minimum signal among the image signals corresponding to each of the plurality of light receiving elements corresponding to the pixels specified by the specifying means When an image signal having a level is to be corrected, the image signal and the corresponding image signal generated prior to the image signal are interpolated between two points to obtain Configured to include a correction means for correcting the color shift, the.

  According to a third aspect of the present invention, in the image reading apparatus according to the fourth aspect of the invention, the correction unit is further configured such that the boundary region detected by the detection unit is changing from a white region to a black region. When an image signal having the maximum signal level among the image signals corresponding to each of the plurality of light receiving elements corresponding to the pixels specified by the specifying unit is corrected, the image signal and the image signal An image corresponding to each of the plurality of light receiving elements corresponding to the pixels specified by the specifying means by correcting the color shift by interpolating between the corresponding image signals generated earlier than two points. When an image signal having the minimum signal level among the signals is to be corrected, the color is obtained by interpolating the image signal and the corresponding image signal generated after the image signal between two points. It was assumed to correct the record.

  On the other hand, in order to solve the above-mentioned problem, the image reading apparatus according to claim 5 is provided with at least one of a recording medium on which an image is recorded and a light source for irradiating light on an image recording area including the image. A moving unit that relatively moves in a direction and a plurality of light receiving elements having different spectral sensitivities arranged in a state shifted in the predetermined direction in units of pixels, and light is emitted to the image recording area during the relative movement by the moving unit. Is generated on the basis of the image signal generated by the generation unit and the generation unit that receives the light reflected by the image recording area and generates an image signal corresponding to each received light amount. Detection means for detecting a boundary area between different achromatic areas in the image recording area, and output from each of the plurality of light receiving elements corresponding to pixels existing in the boundary area detected by the detection means. Among the image signals corresponding to each of the plurality of light receiving elements corresponding to the pixels specified by the specifying means, and specifying means for specifying a pixel in which color misregistration occurs in the boundary region based on the image signal, When the image signal having the maximum signal level is to be corrected and the boundary area detected by the detection means is an area in the middle of changing from a white area to a black area, the image signal to be corrected and the image The color shift is corrected by interpolating between the corresponding image signals generated prior to the signal between two points, and corresponds to each of the plurality of light receiving elements corresponding to the pixels specified by the specifying unit. Among the image signals, an image signal having the maximum signal level is a correction target, and the boundary area detected by the detection unit is changed from a black area to a white area. Correction means for correcting the color misregistration by interpolating between two points of the image signal to be corrected and the corresponding image signal generated after the image signal in the case of the intermediate region. Consists of.

  In the image reading apparatus according to claim 5, as in the invention according to claim 6, the correction unit further corresponds to each of the plurality of light receiving elements corresponding to the pixels specified by the specifying unit. Among image signals, an image signal having a minimum signal level is a correction target, and the boundary region detected by the detection unit is a region in the middle of a change from a white region to a black region, the correction target The color shift is corrected by interpolating between the image signal and the corresponding image signal generated after the image signal between two points, and the plurality of light receiving elements corresponding to the pixels specified by the specifying means Of the image signals corresponding to each, the image signal having the minimum signal level is a correction target, and the boundary area detected by the detection means is in the process of changing from a black area to a white area. If a region, was used to correct the color shift of said image signal corresponding generated before the image signal and the image signal subject to correction by interpolating between two points.

  On the other hand, in order to solve the above-mentioned problem, at least one of a recording medium on which an image is recorded and a light source that irradiates light to an image recording area including the image is predetermined. A moving unit that relatively moves in a direction and a plurality of light receiving elements having different spectral sensitivities arranged in a state shifted in the predetermined direction in units of pixels, and light is emitted to the image recording area during the relative movement by the moving unit. Is generated on the basis of the image signal generated by the generation unit and the generation unit that receives the light reflected by the image recording area and generates an image signal corresponding to each received light amount. Detection means for detecting a boundary area between different achromatic areas in the image recording area, and output from each of the plurality of light receiving elements corresponding to pixels existing in the boundary area detected by the detection means. Among the image signals corresponding to each of the plurality of light receiving elements corresponding to the pixels specified by the specifying means, and specifying means for specifying a pixel in which color misregistration occurs in the boundary region based on the image signal, When an image signal having a minimum signal level is to be corrected, and the boundary area detected by the detection means is an area in the middle of a change from a white area to a black area, the image signal to be corrected and the image An image corresponding to each of the plurality of light-receiving elements corresponding to the pixels specified by the specifying unit by correcting the color shift by interpolating between the corresponding image signals generated after the signal between two points. Among the signals, an image signal having a minimum signal level is a correction target, and the boundary area detected by the detection unit is changed from a black area to a white area. A correction means for correcting the color misregistration by interpolating between the image signal to be corrected and the corresponding image signal generated prior to the image signal between two points, Constructed including.

  In the image reading apparatus according to claim 7, as in the invention according to claim 8, the correction unit further corresponds to each of the plurality of light receiving elements corresponding to the pixels specified by the specifying unit. Among image signals, an image signal having a maximum signal level is a correction target, and the boundary region detected by the detection unit is a region in the middle of a change from a white region to a black region, the correction target The plurality of light receiving elements corresponding to the pixel specified by the specifying means by correcting the color shift by interpolating between the image signal and the corresponding image signal generated before the image signal between two points Among the image signals corresponding to each of the image signals, the image signal having the maximum signal level is set as a correction target, and the boundary area detected by the detection unit is in the process of changing from a black area to a white area. If a region, was used to correct the color shift of said image signal corresponding generated later than the image signal is the correction target and the image signal by interpolating between two points.

  The image reading apparatus according to any one of claims 1 to 8, and the image signals to be interpolated between the two points are adjacent to each other in time series as in the invention according to claim 9. It was assumed that the generated image signal.

  The image reading apparatus according to any one of Claims 1 to 9, and the correction unit uses the plurality of interpolation coefficients for each pair as in the invention according to Claim 10. The intermediate signal level of the image signal corresponding to each of the plurality of light receiving elements corresponding to the pixel specified by the specifying means among the interpolation results obtained by performing the interpolating and performing the interpolation between the two points The interpolation result closest to the signal level of the image signal having a value is applied as the corrected image signal.

  The image reading apparatus according to any one of claims 1 to 10, wherein, as in the invention according to claim 11, the specifying unit detects that the boundary region detected by the detecting unit is a predetermined number of pixels. And the density difference between the achromatic regions across the boundary region is greater than or equal to a predetermined value, and among the pixels existing in the boundary region, output from each of the corresponding light receiving elements A pixel in which the difference between the maximum signal level and the minimum signal level in the image signal is equal to or greater than a predetermined color shift threshold is specified as a pixel in which color shift has occurred.

  The image reading apparatus according to any one of claims 1 to 11, wherein the moving means irradiates the light of the light source onto the image recording area as in the invention according to claim 12. And a conveying means for conveying the recording medium.

  The image reading apparatus according to claim 12 is the same as the invention according to claim 13, wherein the detection unit changes a conveyance speed of the recording medium conveyed by the conveyance unit in the image recording area. The boundary region is detected based on the image signal corresponding to the region irradiated with the light during a predetermined period.

  The image reading apparatus according to any one of claims 1 to 13, and the generation unit according to the invention according to claim 14, wherein the plurality of light receiving elements are arranged in the predetermined direction in units of one pixel. In addition, a plurality of sets of line sensors are arranged in a direction intersecting the predetermined direction for each spectral sensitivity.

  The image reading apparatus according to any one of claims 1 to 14, wherein, as in the invention according to claim 15, the detection means is configured so that the generation order of the image signals is separated by a predetermined number of pixels. As a value indicating that the absolute value of the difference between the maximum signal level and the minimum signal level among the signal levels of the image signals corresponding to the plurality of light receiving elements related to the previous pixel is white. The plurality of conditions relating to a later pixel satisfying one of a condition that it is within a predetermined white reference value and a condition that is within a predetermined black reference value as a value indicating black A condition that the absolute value of the difference between the maximum signal level and the minimum signal level among the signal levels of the image signals corresponding to the light receiving elements is within the predetermined white reference value and the predetermined Other than the condition that it is within the black reference value The region sandwiched by the first pixel and the subsequent pixel when satisfying the condition was assumed to be detected as the boundary region.

  On the other hand, in order to solve the above-mentioned problem, the program according to claim 16 is executed at least of an image recording area including the image on a recording medium on which the image is recorded and a light source that irradiates the image recording area with light. A moving unit that relatively moves one side in a predetermined direction and a plurality of light receiving elements with different spectral sensitivities arranged in a state shifted in the predetermined direction in units of one pixel, and the image recording during the relative movement by the moving unit The image reading apparatus includes: a generation unit configured to receive light reflected by the image recording area by irradiating the area with the plurality of light receiving elements and generate an image signal corresponding to each amount of received light; Detecting means for detecting a boundary area between different achromatic areas in the image recording area based on the image signal generated by the generating means; Based on the image signal output from each of the plurality of light receiving elements corresponding to the pixels existing in the boundary region, a specifying unit that specifies a pixel in which color misregistration has occurred in the boundary region, and detected by the detection unit An image having a maximum signal level among the image signals corresponding to each of the plurality of light receiving elements corresponding to the pixels specified by the specifying means with respect to an area where the boundary area is changing from a white area to a black area. When a signal is a correction target, the color misregistration is corrected by interpolating between the image signal and the corresponding image signal generated before the image signal between two points, and specified by the specifying unit When an image signal having a minimum signal level among image signals corresponding to each of the plurality of light receiving elements corresponding to a pixel is to be corrected, the image signal and the image signal It was assumed to function and the image signal corresponding generated later than the signal as a correction means for correcting the color shift by interpolating between two points.

  On the other hand, in order to solve the above problem, the program according to claim 17 is arranged so that at least one of a recording medium on which an image is recorded and a light source that irradiates light to an image recording area including the image is in a predetermined direction. A moving means for relative movement and a plurality of light receiving elements with different spectral sensitivities arranged in a state shifted in the predetermined direction are provided in units of one pixel, and light is applied to the image recording area during the relative movement by the moving means. A generating unit that receives the light reflected by the image recording area by the plurality of light receiving elements and generates an image signal corresponding to each amount of received light. Detection means for detecting a boundary area between different achromatic areas in the image recording area based on the generated image signal, and pixels existing in the boundary area detected by the detection means A specifying means for specifying a pixel in which color misregistration occurs in the boundary area based on the image signal output from each of the plurality of corresponding light receiving elements; and the boundary area detected by the detecting means is a black area When an image signal having a maximum signal level is selected as a correction target among image signals corresponding to each of the plurality of light receiving elements corresponding to the pixel specified by the specifying means for the region in the middle of the change from the white region to the white region The color shift is corrected by interpolating between the image signal and the corresponding image signal generated after the image signal between two points, and the plurality of light receptions corresponding to the pixels specified by the specifying unit When the image signal having the minimum signal level among the image signals corresponding to each of the elements is to be corrected, the image signal and the image signal generated before the image signal are generated. And said image signal response was intended to function as a correction means for correcting the color shift by interpolating between two points.

  On the other hand, in order to solve the above-mentioned problem, at least one of a recording medium on which an image is recorded and a light source that irradiates light to an image recording area including the image is set in a predetermined direction. A moving means for relative movement and a plurality of light receiving elements with different spectral sensitivities arranged in a state shifted in the predetermined direction are provided in units of one pixel, and light is applied to the image recording area during the relative movement by the moving means. A generating unit that receives the light reflected by the image recording area by the plurality of light receiving elements and generates an image signal corresponding to each amount of received light. Detection means for detecting a boundary area between different achromatic areas in the image recording area based on the generated image signal, and pixels existing in the boundary area detected by the detection means A specifying unit for specifying a pixel in which color misregistration occurs in the boundary region based on the image signal output from each of the plurality of corresponding light receiving elements; and the plurality corresponding to the pixel specified by the specifying unit Among the image signals corresponding to each of the light receiving elements, the image signal having the maximum signal level is a correction target, and the boundary area detected by the detection means is an area in the middle of changing from a white area to a black area In this case, the color shift is corrected by interpolating between the image signal to be corrected and the corresponding image signal generated before the image signal between two points, and the pixel specified by the specifying unit Among the image signals corresponding to each of the plurality of light receiving elements corresponding to the image signal having the maximum signal level as a correction target and detected by the detection means. When the boundary region is a region in the middle of a change from a black region to a white region, interpolation between the image signal to be corrected and the corresponding image signal generated after the image signal is performed between two points. In order to function as correction means for correcting the color misregistration.

  On the other hand, in order to solve the above-mentioned problem, at least one of a recording medium on which an image is recorded and a light source that irradiates light to an image recording area including the image is set in a predetermined direction. A moving means for relative movement and a plurality of light receiving elements with different spectral sensitivities arranged in a state shifted in the predetermined direction are provided in units of one pixel, and light is applied to the image recording area during the relative movement by the moving means. A generating unit that receives the light reflected by the image recording area by the plurality of light receiving elements and generates an image signal corresponding to each amount of received light. Detection means for detecting a boundary area between different achromatic areas in the image recording area based on the generated image signal, and pixels existing in the boundary area detected by the detection means A specifying unit for specifying a pixel in which color misregistration occurs in the boundary region based on the image signal output from each of the plurality of corresponding light receiving elements; and the plurality corresponding to the pixel specified by the specifying unit Among the image signals corresponding to each of the light receiving elements, the image signal having the minimum signal level is an object to be corrected, and the boundary area detected by the detecting means is an area in the middle of changing from a white area to a black area In this case, the color misregistration is corrected by interpolating between the image signal to be corrected and the corresponding image signal generated after the image signal between two points, and the pixel specified by the specifying unit is corrected. Among the image signals corresponding to each of the corresponding light receiving elements, the image signal having the minimum signal level is to be corrected and detected by the detection means. When the boundary region is a region in the middle of a change from a black region to a white region, interpolation is performed between the image signal to be corrected and the corresponding image signal generated before the image signal between two points. Thus, the color misregistration is made to function as a correction unit.

  According to the first, third, fifth, seventh and sixteenth to nineteenth aspects of the present invention, the image to be corrected is related to a pixel existing in a boundary region between different achromatic regions. Compared to the case where the configuration for performing interpolation between two points using a signal is not provided, an effect that color shift between different achromatic regions is corrected with high accuracy is obtained.

  According to the second aspect of the present invention, the boundary region detected by the detecting unit corresponds to each of the plurality of light receiving elements corresponding to the pixel specified by the specifying unit for the region in the middle of the change from the black region to the white region. When the image signal having the maximum signal level is to be corrected among the image signals to be corrected, the color misregistration is corrected by interpolating between the image signal and the corresponding image signal generated after the image signal. When the image signal having the minimum signal level among the image signals corresponding to each of the plurality of light receiving elements corresponding to the pixel specified by the specifying unit is to be corrected, the image signal and the image signal are preceded. Compared to the case where there is no configuration that corrects color misregistration by interpolating between the corresponding image signals generated at 2 points, color misregistration between different achromatic regions is corrected with higher accuracy. The effect is obtained that.

  According to the fourth aspect of the present invention, the boundary region detected by the detecting unit corresponds to each of the plurality of light receiving elements corresponding to the pixel specified by the specifying unit for the region in the middle of the change from the white region to the black region. When the image signal having the maximum signal level is to be corrected among the image signals to be corrected, color misregistration is performed by interpolating between the image signal and the corresponding image signal generated prior to the image signal. When an image signal having a minimum signal level among the image signals corresponding to each of the plurality of light receiving elements corresponding to the pixels specified by the specifying unit is corrected, the image signal and the image signal are Compared to the case where there is no configuration for correcting color misregistration by interpolating between corresponding image signals generated later at two points, color misregistration between different achromatic regions is corrected with higher accuracy. The effect is obtained that.

  According to the invention of claim 6, among the image signals corresponding to each of the plurality of light receiving elements corresponding to the pixels specified by the specifying means, the image signal having the minimum signal level is to be corrected, and the detection means When the detected boundary region is a region in the middle of the change from the white region to the black region, the image signal to be corrected and the corresponding image signal generated after the image signal are interpolated between two points. The color misregistration is corrected with the image signal corresponding to each of the plurality of light receiving elements corresponding to the pixels specified by the specifying means, and the image signal having the minimum signal level is to be corrected and detected by the detecting means. When the boundary region is a region in the middle of changing from the black region to the white region, the image signal to be corrected and the corresponding image signal generated prior to the image signal are between two points. Compared with the case of not having the structure of correcting the color shift by between color shift between different achromatic region is corrected with higher accuracy, the effect is obtained that.

  According to the eighth aspect of the invention, among the image signals corresponding to each of the plurality of light receiving elements corresponding to the pixels specified by the specifying means, the image signal having the maximum signal level is to be corrected, and the detection means When the detected boundary region is a region in the middle of the change from the white region to the black region, the image signal to be corrected and the corresponding image signal generated before the image signal are interpolated between two points. Thus, the color misregistration is corrected, and among the image signals corresponding to each of the plurality of light receiving elements corresponding to the pixels specified by the specifying means, the image signal having the maximum signal level is targeted for correction and detected by the detecting means. If the boundary region is a region in the middle of changing from the black region to the white region, the image signal to be corrected and the corresponding image signal generated after the image signal are Compared with the case of not having the structure of correcting the color shift by between color shift between different achromatic region is corrected with higher accuracy, the effect is obtained that.

  According to the ninth aspect of the present invention, the image signals to be interpolated between the two points are compared between different achromatic regions as compared with the case where the image signals are generated adjacent to each other in time series. There is an effect that the color shift is corrected with higher accuracy.

  According to the invention of claim 10, the correcting means performs two-point interpolation using a plurality of sets of interpolation coefficients for each set, and the specifying means among the interpolation results obtained by performing the two-point interpolation is specified by the specifying means. When there is no configuration to apply the interpolation result closest to the signal level of the image signal having the intermediate signal level among the image signals corresponding to each of the plurality of light receiving elements corresponding to the selected pixel as the corrected image signal In comparison, it is possible to obtain an effect that a color shift between different achromatic regions is corrected with higher accuracy.

  According to the eleventh aspect of the invention, the specifying means has the boundary area detected by the detecting means within a predetermined number of pixels, and the density difference between the achromatic areas sandwiching the boundary area is not less than a predetermined value. The difference between the maximum signal level and the minimum signal level of the image signals output from each of the corresponding light receiving elements among the pixels existing in the boundary region is equal to or greater than a predetermined color misregistration threshold. Compared to a case where the pixel is not configured to identify a pixel where color misregistration has occurred, an effect that the color misregistration between different achromatic regions can be identified with high accuracy can be obtained.

  According to the twelfth aspect of the present invention, compared to the case where the recording medium is not transported so that the light of the light source is irradiated on the image recording area, the transport speed is rapidly increased while the recording medium is transported. An effect is obtained that a color shift caused by a large change is detected with high accuracy.

  According to the thirteenth aspect of the present invention, the image signal corresponding to an area irradiated with light in a predetermined period as a period during which the conveyance speed of the recording medium conveyed by the conveying means in the image recording area changes. As compared with the case where the configuration for detecting the boundary region based on the above is not provided, an effect that the color misregistration is detected with high accuracy and speed can be obtained.

  According to the invention of claim 14, a plurality of light receiving elements are arranged along a predetermined direction in units of one pixel, and a plurality of line sensors are arranged for each spectral sensitivity in a direction intersecting the predetermined direction. Compared to the case without the above configuration, an effect that a wide range of color misregistration is detected with high accuracy can be obtained.

  According to the fifteenth aspect of the present invention, the maximum signal among the signal levels of the respective image signals corresponding to the plurality of light receiving elements according to the preceding pixel, with respect to the pixel preceding the predetermined number of pixels in the generation order of the image signal. The condition that the absolute value of the difference between the level and the minimum signal level is within a predetermined white reference value as a value indicating white and a black reference value predetermined as a value indicating black The absolute value of the difference between the maximum signal level and the minimum signal level among the signal levels of the image signals corresponding to the plurality of light receiving elements related to the subsequent pixels is satisfied. An area sandwiched between the previous pixel and the subsequent pixel when the other condition of being within a predetermined white reference value and the condition of being within a predetermined black reference value is satisfied Does not have a configuration to detect as a boundary region When compared with the boundary regions are detected in the color shift is highly accurate and easily detected, the effect is obtained that.

It is a schematic block diagram which shows an example of a structure of the image processing apparatus which concerns on embodiment. 1 is a schematic end view illustrating an example of a configuration of a scanner of an image processing apparatus according to an embodiment and a block diagram illustrating some functions. 1 is a schematic configuration diagram illustrating an example of an image reading sensor included in a scanner according to an embodiment. It is a block diagram which shows an example of the principal part structure of the electric system of the image processing apparatus which concerns on embodiment. It is a block diagram which shows an example of the signal processing part contained in the scanner which concerns on embodiment. FIG. 3 is a block diagram illustrating an example of a color misregistration detection / correction circuit included in the signal processing unit according to the embodiment. It is a flowchart which shows an example of the flow of the achromatic color / color misregistration detection process which concerns on embodiment. The density value of each color of image data obtained by reading an original having an image recording area on which a ladder pattern in which white areas and black areas are alternately arranged along the conveyance direction is recorded, and conveyance of the original It is a graph which shows an example of correlation with the position of a direction. It is a flowchart which shows an example of the flow of the color misregistration detection process which concerns on embodiment. It is explanatory drawing for demonstrating the method of pinpointing the change point of the achromatic color area employ | adopted by the achromatic color and color shift detection process which concerns on embodiment. It is a graph which shows an example of the relationship between the density value of each color and the position of a conveyance direction with which it uses for description of the color shift detection method employ | adopted by the color shift detection process which concerns on embodiment. 6 is a flowchart illustrating an example of a flow of color misregistration correction processing according to the embodiment. It is a graph which shows an example of the relationship between the density value of each color and the position of a conveyance direction used for description of the correction method by the interpolation between two points employ | adopted by the color shift correction process.

  Hereinafter, an example of an embodiment for carrying out the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram illustrating an example of a schematic configuration of an image processing apparatus 10 according to the present embodiment. The image processing apparatus 10 includes a scanner 12, an image forming unit 14, a paper feed tray 16, and a UI (user interface) panel 18.

  The scanner 12 includes a document table 22 and a discharge table 24. A pair of guides 26 </ b> A and 26 </ b> B are provided on the upper surface of the document table 22. One of the pair of guides 26A and 26B is manually moved in the width direction of the document placed on the document table 22, and guides the document when the document placed on the document table 22 is conveyed. The scanner 12 fetches the originals placed on the original table 22 one by one, reads the read originals, obtains image information indicating an image of the read originals, and then discharges the originals to the discharge table 24.

  On the other hand, the image forming unit 14 takes out a recording sheet that is an example of a recording medium accommodated in the paper feed tray 16, forms an image based on the image information acquired by the scanner 12 on the removed recording sheet, The recording sheet on which the image is formed is discharged to the discharge table 32.

  The UI panel 18 includes a touch panel display 34 and a switch 36 for displaying an image. The touch panel display 34 and the switch 36 are used to read a document by the scanner 12 and form an image on a recording sheet by the image forming unit 14. Various instructions are input by the user, and necessary items are displayed on the touch panel display 34.

  FIG. 2 is a schematic end view showing an example of the configuration of the scanner 12 according to the present embodiment and a block diagram showing a part of the configuration of the electrical system around it. As shown in FIG. 2, the scanner 12 is roughly divided into an original conveying unit 40 arranged in the upper stage and an image reading unit 42 arranged in the lower stage. The document transport unit 40 transports a document placed on the document table 22. The image reading unit 42 reads the document conveyed by the document conveying unit 40 and outputs image information indicating an image obtained by reading.

  The document transport unit 40 touches the document table lifter 44 for raising and lowering the document table 22 and the uppermost surface of the bundle of documents on the document table 22 raised by the document table lifter 44, and takes the documents one by one. A document take-in roller 46 and a feed roller 50 that sends a document taken in by the document take-in roller 46 to a conveyance path 48 are provided.

  In the conveyance path 48 where the document is conveyed, a conveyance roller 52 that conveys the document further downstream in the conveyance direction (in the direction of arrow B in FIG. 2), and a pre-positioning roller that conveys the document further downstream and creates a loop 54, an alignment roller 56 for supplying the document while performing registration adjustment on the document reading unit, a platen roller 58 for assisting the conveyance of the document to be read, and the document on which the image is read further downstream An out-roller 60 is provided. The transport path 48 is provided on the downstream side in the transport direction of the document with respect to the baffle 62 that rotates about the fulcrum according to the loop state of the transported document and the out roller 60, and the document is supplied to the discharge table 24. Is provided with a discharge roller 64.

  Next, a document transport operation in the scanner 12 according to the present embodiment will be briefly described.

  The document take-in roller 46 is lifted up and held at the retracted position during standby when the document is not transported, and descends to the nip position (document transport position) during document transport to transport the uppermost document on the document table 22. To do. The pre-alignment roller 54 makes a loop by abutting the leading end of the document against the stopped alignment roller 56. When this loop is formed, the baffle 62 opens around the fulcrum and functions so as not to interfere with the document loop. Further, the transport roller 52 and the pre-positioning roller 54 hold a loop during image reading. By forming this loop, the document reading timing is adjusted, and the skew associated with document conveyance at the time of document reading is suppressed to enhance the alignment adjustment function. Then, the alignment roller 56 that has been stopped starts rotating in accordance with the document reading start timing, and the document is conveyed. The conveyed document is pressed by a platen roller 58 against a second platen glass 70B described later and read from the lower surface.

  On the other hand, the image reading unit 42 is provided with a transparent first platen glass 70A on which an original is placed and a transparent second platen glass 70B that forms an opening for reading the original being conveyed by the original conveying unit 40. It has been.

  Below the first platen glass 70A and the second platen glass 70B, a light source 72 that irradiates illumination light toward the surface of the document, a first reflection mirror 74 that receives reflected light reflected by the surface of the document, and a first A second reflecting mirror 76 for bending the traveling direction of the reflected light received by the reflecting mirror 74 by 90 ° and a third reflecting mirror 78 for further bending the traveling direction of the reflected light received by the second reflecting mirror 76 by 90 ° Is provided.

  In the image reading unit 42 according to the present embodiment, a fluorescent lamp is used as the light source 72. However, the present invention is not limited to this, and a plurality of LEDs (Light Emitting Diodes) arranged along the direction intersecting the document conveying direction are used. For example, other light sources may be used.

  Further, the image reading unit 42 includes a lens 80 and an image reading sensor 82, and the image reading unit 42 forms an image of the reflected light reflected by the third reflection mirror 78 on the image reading sensor 82 by the lens 80. Thus, the document is read by the image reading sensor 82.

  In the image reading unit 42 according to the present embodiment, as an image reading sensor 82 which is an example of a generation unit that generates an image signal, a CCD corresponding to each pixel for each of a plurality of light receiving elements (photodiodes as an example). A CCD line sensor configured with (Charge Coupled Device) is applied. This CCD line sensor is provided for each different spectral sensitivity, and each CCD line sensor generates an image signal corresponding to the amount of light received by each light receiving element and outputs it to the subsequent stage. That is, the optical image formed by the lens 80 is photoelectrically converted to generate red (R), green (G), and blue (B) color image signals, which are output to the subsequent stage. In this embodiment, a CCD line sensor is applied. However, the present invention is not limited to this, and a solid-state imaging device such as a CMOS (Complementary Metal-Oxide Semiconductor) image sensor may be used.

  Further, in the image reading unit 42 according to the present embodiment, the light source 72 and the first reflection mirror 74 are moved in the direction of arrow C in FIG. 3 by the carriage 83A, and the second reflection mirror 76 and the third reflection mirror 78 are moved by the carriage 83B. It is supposed to be free. Thus, when the document is placed on the upper surface of the first platen glass 70A, the light source 72, the first reflection mirror 74, and the second reflection mirror are irradiated in the direction of arrow C while irradiating the illumination light from the light source 72 toward the document. 76 and the third reflecting mirror 78 are moved to read the original.

  Further, the image reading unit 42 includes a signal processing unit 84. The input end of the signal processing unit 84 is connected to the output end of the image reading sensor 82. Therefore, the signal processing unit 84 receives image signals of each color from the image reading sensor 82, and performs predetermined signal processing on the input image signals of each color (here, R, G, B as an example). Digital image data (hereinafter referred to as image data) is output to the subsequent stage.

  FIG. 3 is a schematic configuration diagram illustrating an example of the configuration of the image reading sensor 82 of the image reading unit 42. In the following description, the relative movement direction of the original and the light source 72 is referred to as the sub-scanning direction SS (or the transport direction SS), and the direction intersecting (subjecting as an example) the sub-scanning direction is referred to as the main scanning direction FS. Called. As shown in FIG. 3, the image reading sensor 82 includes a rectangular substrate 82a, a red CCD line sensor 82R, a green CCD line sensor 82G, and a blue CCD provided on the substrate 82a and having different spectral sensitivities. A line sensor 82B is provided. The red CCD line sensor 82R, the green CCD line sensor 82G, and the blue CCD line sensor 82B each extend along the main scanning direction FS and are arranged in the sub-scanning direction SS. Each of the red CCD line sensor 82R, the green CCD line sensor 82G, and the blue CCD line sensor 82B according to the present embodiment is configured by arranging N photodiodes 19 in a straight line in the main scanning direction FS. Yes. Further, the distance between the red CCD line sensor 82R and the green CCD line sensor 82G and the distance between the green CCD line sensor 82G and the blue CCD line sensor 82B are respectively equal to four main scanning lines in the sub-scanning direction SS. (Hereinafter simply referred to as 4 lines).

  The blue CCD line sensor 82B outputs an image signal B representing the blue component of each of the N pixels arranged in a straight line in the main scanning direction FS to the signal processing unit 84. The green CCD line sensor 82G is an image representing the green components of N pixels arranged in a straight line in the main scanning direction FS downstream of the blue CCD line sensor 82B by an amount corresponding to four lines in the sub scanning direction SS. The signal G is output to the signal processing unit 84. Further, the red CCD line sensor 82R is an image signal R representing the red component of N pixels arranged in a straight line in the main scanning direction FS downstream of the green reading position RG by the amount corresponding to four lines in the sub scanning direction SS. Is output to the signal processing unit 84.

  FIG. 4 is a block diagram illustrating an example of a main configuration of the electrical system of the image processing apparatus 10 according to the present embodiment. As shown in FIG. 4, the image processing apparatus 10 includes an image forming unit 14, a UI panel 18, a controller 100, a secondary storage unit 102, and an external I / F (interface) 104.

  The controller 100 controls the overall operation of the image processing apparatus 10, and includes a CPU (Central Processing Unit) 100A, a RAM (Read Only Memory) 100B, and a ROM (Read Only Memory) 100C. The RAM 100B is a memory used as a work area when various programs are executed, and various programs, various parameters, various table information, and the like are stored in advance in the ROM 100C. The CPU 100A fetches the program stored in the ROM 100C into the RAM 100B, executes the fetched program, and controls the overall operation of the image processing apparatus 10.

  The external I / F 104 is connected to an external device 110 such as a personal computer, and is used for the controller 100 and the external device 110 to exchange various information with each other.

  The CPU 100A, RAM 100B, ROM 100C, secondary storage unit 102, scanner 12, image forming unit 14, UI panel 18 and external I / F 104 are connected to each other via a bus 108 such as an address bus, a data bus, and a control bus. . Accordingly, the CPU 100A accesses the RAM 100B, the ROM 100C, and the secondary storage unit 102, displays various types of information on the UI panel 18, grasps the contents of user operation instructions on the UI panel 18, and passes the external I / F 104. Each exchange of various information with the external device 110, grasping of the operation state of the scanner 12 and the image forming unit 14, and control of the operation of the scanner 12 and the image forming unit 14 are performed.

  FIG. 5 is a block diagram showing an example of the configuration of the signal processing unit 84 according to the present embodiment. As shown in FIG. 5, the signal processing unit 84 includes a sample hold 112, a black level adjustment circuit 114, an output amplification circuit 116, an AD conversion circuit 118, a shading correction circuit 120, an output delay circuit 122, and a color misregistration detection / correction circuit 124. The image processing circuit 126 and the CPU 128 are included. Output terminals corresponding to the image signals B, G, and R of the image reading sensor 82 are connected to corresponding input terminals of the sample hold circuit 112. In the sample and hold circuit 112, output terminals corresponding to the image signals B, G, and R related to the image reading sensor 82 are connected to corresponding input terminals of the black level adjusting circuit 114. In the black level adjustment circuit 114, output terminals corresponding to the image signals B, G, and R related to the image reading sensor 82 are connected to corresponding input terminals of the output amplifier circuit 116. In the output amplifier circuit 116, output terminals corresponding to the image signals B, G, and R related to the image reading sensor 82 are connected to corresponding input terminals of the AD conversion circuit 118. In the AD conversion circuit 118, output terminals corresponding to the image signals B, G, and R related to the image reading sensor 82 are connected to corresponding input terminals of the shading correction circuit 120. In the shading correction circuit 120, output terminals corresponding to the image signals B and G related to the image reading sensor 82 are connected to corresponding input terminals of the output delay circuit 122. In the shading correction circuit 120, an output terminal corresponding to the image signal R related to the image reading sensor 82 is connected to a corresponding input terminal of the color misregistration detection / correction circuit 124. In the output delay circuit 122, output terminals corresponding to the image signals B and G related to the image reading sensor 82 are connected to corresponding input terminals of the color misregistration detection / correction circuit 124. In the color misregistration detection / correction circuit 124, output terminals corresponding to the image signals B, G, and R related to the image reading sensor 82 are connected to corresponding input terminals of the image processing circuit 126. The CCD drive circuit 130 has an output end connected to the input end of the image reading sensor 82.

  The sample hold circuit 112 performs sampling hold for sampling (sampling) the image signals B, G, R inputted from the image reading sensor 82 and holding (holding) them for a predetermined period.

  The black level adjustment circuit 114 adjusts the image signals B, G, and R sampled and held by the sample hold circuit 112 so that the output corresponding to the black color of the read original does not differ from the black level of the output of the scanner 12. To do.

  The output amplifier circuit 116 amplifies the image signals B, G, R after the black level adjustment. The A / D conversion circuit 118 performs A / D conversion on the image signals B, G, and R amplified by the output amplifier circuit 116, and converts them into image data B, G, and R that are digital data.

  The shading correction circuit 120 corrects variations in read output caused by the light source 72 and the CCD line sensors 82B, 82G, and 82R with respect to the image data B, G, and R obtained by conversion by the A / D conversion circuit 118. At the same time, so-called shading correction is performed to adjust so that the output corresponding to the white color of the read document does not differ from the white level of the output of the scanner 12.

  The output delay circuit 122 calculates a reading time difference between the image data caused by the positional deviation in the sub scanning method SS of the blue CCD line sensor 82B, the green CCD line sensor 82G, and the red CCD line sensor 82R. Correction is performed based on the image data R. In the present embodiment, the image data G output from the shading correction circuit 120 is output as image data in phase with the image data R by delaying the image data G by a delay time corresponding to 4 lines and the image data B corresponding to 8 lines. Yes.

  The color misregistration detection / correction circuit 124 is based on the input image data B, R, and G, and a boundary region between achromatic regions in a predetermined region (for example, an image recording region described later) of the read original ( The boundary area between the white area and the black area is detected, and a color that is not recognized as black or white in the detected boundary area and that is likely to be visually recognized by the naked eye is a color that is determined in advance. The occurrence (color misregistration) is detected, and the detected color misregistration is corrected in pixel units.

  The image processing circuit 126 performs various image processing, such as color space conversion, enlargement / reduction processing, ground color removal processing, and binarization processing, on the image data B, G, and R output from the color misregistration / correction circuit 124. Is output to the subsequent stage.

  The CPU 128 is connected to a sample hold circuit 112, a black level adjustment circuit 114, an output amplification circuit 116, an AD conversion circuit 118, a shading correction circuit 120, a color shift detection / detection circuit, and the like via a bus 132 such as an address bus, a data bus, and a control bus. The correction circuit 124, the image processing circuit 126, and the CCD driving circuit 130 are connected. Therefore, the CPU 128 controls the operation of the image reading sensor 82 via the CCD drive circuit 130 under the control of the controller 100, and also includes the sample hold circuit 112, the black level adjustment circuit 114, the output amplification circuit 116, and the AD conversion circuit 118. The operation status of the shading correction circuit 120, the color misregistration detection / correction circuit 124, and the image processing circuit 126 is ascertained and the operation is controlled.

  FIG. 6 is a block diagram showing an example of the configuration of the color misregistration detection / correction circuit 124 according to the present embodiment. As shown in FIG. 6, the color misregistration detection / correction circuit 124 includes an image data holding circuit 124A, a comparison circuit 124B, a threshold memory 124C, an arithmetic circuit 124D, and an interpolation coefficient memory 124E.

  The output terminals of the image data B and G related to the output delay circuit 122 and the output terminal of the image data R related to the shading correction circuit 120 are connected to input terminals corresponding to the respective colors in the image data holding circuit 124A. The image data holding circuit 124A is connected to each of the comparison circuit 124B and the calculation circuit 124D so that the image data B, G, and R are supplied to the comparison circuit 124B and the calculation circuit 124D. The comparison circuit 124B is connected to the arithmetic circuit 124D. The arithmetic circuit 124D is connected to the subsequent image processing circuit 126. A threshold memory 124C is connected to the comparison circuit 124B. An interpolation coefficient memory 124E is connected to the arithmetic circuit 124D.

  The image data holding circuit 124A is a circuit that holds each of the input image data B, G, and R in units of pixels. The image data holding circuit 124A has a predetermined number of pixels (FIFO (First-in First-out) format) in a time series ( For example, 7 pixels). The threshold memory 124C stores threshold values (thresholds) ThC, ThD, ThΔW, and ThΔB in advance. The comparison circuit 124B compares the image data input from the image data holding circuit 124A with the threshold values ThC, ThD, ThΔW, ThΔB read from the threshold memory 124C, and outputs a signal corresponding to the comparison result to the arithmetic circuit 124D. At the same time, the input image data B, G, R is transferred to the arithmetic circuit 124D. The interpolation coefficient memory 124E stores in advance a plurality of sets of interpolation coefficients used in the calculation of two-point interpolation. The arithmetic circuit 124D performs a predetermined calculation using the image data input from the image holding data holding circuit 124A and the interpolation coefficient read from the interpolation coefficient memory 124E.

  By the way, the positional relationship among the blue CCD line sensor 82B, the green CCD line sensor 82G, and the red CCD line sensor 82R is shifted along the sub-scanning direction SS as described above. Therefore, in the signal processing unit 84 according to the present embodiment, the output of the image data B and G obtained by the CCD line sensor of a specific color (here, the blue CCD line sensor 82B and the green CCD line sensor 82G as an example). The output is delayed so as to match the output timing of the image data R (output as image data in phase with the image data R).

  However, when the conveyance speed of the document in the conveyance path 48 changes abruptly, the image data B and G related to one pixel to be read is handled in the delay time of the image data B and G that is assumed in advance. Therefore, it becomes difficult to output in accordance with the image data R to be output. For example, even if the image data B and G are combined with a predetermined delay time for one pixel (target pixel) to be read on the document, the image data relating to the other pixels is the image data R. Become. This appears as “color shift”. The occurrence of this color shift is caused by delaying the image data B and G at a fixed time interval.

  When such a color misregistration occurs, the color image may not be read correctly even though the color image is actually inserted into the boundary area (monochrome boundary area) of the achromatic image in the actual document ( On the other hand, there is a possibility that the color image may be read as if it was inserted (false detection) even though no color image is inserted in the boundary area of the achromatic image. is there.

  Therefore, in the image processing apparatus 10 according to the present embodiment, the color misregistration detection / correction circuit 124 of the signal processing unit 84 performs achromatic / color misregistration detection processing and color misregistration in order to suppress the occurrence of the above color misregistration. Correction processing is executed.

  In the image processing apparatus 10 according to the present embodiment, various processes for realizing the achromatic color / color misregistration detection process and the color misregistration correction process are performed as shown in the color misregistration detection / correction circuit 124 shown in FIG. 6 as an example. It is realized by the hardware configuration. However, the present invention is not limited to such a hardware configuration, and it goes without saying that it may be realized by a software configuration or a combination of a hardware configuration and a software configuration. When relying on the software configuration, an example in which an achromatic color / color misregistration detection process and a color misregistration correction process are realized by executing a program corresponding to each process by a CPU (central processing unit). In this case, a form in which each program is stored in the ROM in advance, a form in which the stored contents are stored in a recording medium that is read by a computer, a form in which the program is distributed via wired or wireless communication means, etc. May be applied.

  Hereinafter, a case where the color misregistration detection / correction circuit 124 according to the present embodiment executes each process of the achromatic color / color misregistration detection process and the color misregistration correction process will be described.

  FIG. 7 is a flowchart showing an example of the flow of achromatic / color shift detection processing according to the present embodiment. Here, in order to avoid complications, the document placed on the document table 22 is to be read, and an instruction to start reading the document is received by the UI panel 18. A case will be described in which the image reading sensor 82 starts reading a document by being taken in and conveyed by the conveyance unit 40. Here, in order to avoid complications, the image reading sensor 82 is an image recording area of a document having an image recording area in which a ladder pattern in which white areas and black areas are alternately arranged along the conveyance direction SS is recorded. A case of reading by the above will be described. Further, here, in order to avoid complication, as shown in FIG. 8 as an example, a period in which a sudden change in the conveyance speed is expected (conveyance in which in-phase output of image data of each color is difficult to realize in the above delay time) A case where the achromatic color / color shift detection process is executed in a speed change prediction period α that is predetermined as a period during which a speed change is expected will be described.

  FIG. 8 shows density values of the colors of the image data B, G, R obtained by reading the image recording area of the document conveyed in the conveyance direction SS by the image reading sensor 82 (signals of the colors specified by the image data). 6 is a graph showing an example of a correlation between a pixel value B, G, R) corresponding to a level and a position in a document transport direction SS. As shown in FIG. 8, when the image recording area is read by the image reading sensor 82, the density change of each color of the image data B, G, R is represented by a waveform graph corresponding to the ladder pattern in the transport direction SS. The top of the waveform graph is the density value obtained by reading the black area, and the bottom of the waveform is the density value obtained by reading the white area. In the example shown in FIG. 8, the density value difference of each color in a pixel unit is large during the change from the density value obtained by reading the white area to the density value obtained by reading the black area (see FIG. 8). There is a region surrounded by a broken line). The reason for the presence of such a location is that pixels different from the pixels that should be read are read and output as image data because the document transport speed has changed sharply. Therefore, in the present embodiment, the period including the reading period corresponding to the position of the document including the area surrounded by the broken line in FIG. 8 is previously known as a speed change prediction period α through experiments, simulations, or the like. In the speed change prediction period α, the achromatic / color shift detection process is executed. Here, the speed change prediction period α is taken as an example, but other periods include the period including the time when the trailing edge of the document comes out of the alignment roller 56 and the time when the leading edge of the document is sandwiched between the discharge rollers 64. Examples include the period of inclusion.

  In step 200 of FIG. 7, after waiting for input of the image data B, G, R, the process proceeds to step 202, and the image data B, G, R is held in the image data holding circuit 124A for each pixel. In the next step 204, when the image data B, G, R for the predetermined number of pixels is not held in the image data holding circuit 124A, the process returns to step 200, while the image data holding circuit 124A determines the image data. When the image data B, G, R for the number of pixels is held, the process proceeds to step 206. Here, “7” is applied as the predetermined number of pixels. However, the number of pixels is not limited to this, and any number of pixels may be used as long as the number is three or more.

  In step 206, the image data B, G, R corresponding to the center pixel among the image data B, G, R for the seven pixels currently held in the image data holding circuit 124A is used as the image data B of the target pixel. , G, and R, the process proceeds to step 208.

  In step 208, the difference between the pixel values G specified by the image data of the specific color (here, “G” as an example) of pixels separated by a plurality of pixels (here, 4 pixels as an example) from the target pixel is calculated. After the calculation, the process proceeds to step 210. In step 210, if the difference calculated in step 208 is greater than “0”, the process proceeds to step 212. If the difference calculated in step 208 is “0” or less, the process proceeds to step 226. .

  In step 212, if the difference calculated in step 208 is less than the threshold ThD, the process proceeds to step 238. On the other hand, if the difference calculated in step 208 is greater than or equal to the threshold ThD, the process proceeds to step 214. In step 214, the maximum pixel of the pixel values B, G, and R specified by the image data B, G, and R relating to the pixel read before the target pixel among the pixels to be calculated in step 208 above. The difference between the value and the minimum pixel value is calculated. In the next step 216, if the difference calculated in step 214 exceeds the threshold ThΔW, the process proceeds to step 238. If the difference calculated in step 214 is equal to or less than the threshold ThΔW, the process proceeds to step 218. To do. Here, “ThΔW” means a white reference value determined in advance as a value indicating that the color formed by the image data B, G, R is white. If the difference calculated in step 214 is not within the white reference value, it is determined that the color is not white, and if it is within the white reference value, it is determined that the color is white.

  In step 218, the maximum pixel value of the pixel values B, G, and R specified by the image data B, G, and R related to the pixel read after the target pixel among the pixels that were calculated in step 208 above. And the difference between the minimum pixel value and the minimum pixel value. In the next step 220, if the difference calculated in step 218 exceeds the threshold ThΔB, the process proceeds to step 238. If the difference calculated in step 218 is equal to or less than the threshold ThΔB, the process proceeds to step 222. To do. Here, “ThΔB” means a black reference value determined in advance as a value indicating that the color formed by the image data B, G, R is black. If the difference calculated in step 218 is not within the black reference value, it is determined that the color is not black, and if it is within the black reference value, it is determined that the color is black.

  In step 222, after outputting a black and white changing signal indicating that the target pixel specified in step 206 is a pixel existing in the middle of changing from white to black, the process proceeds to step 224. In step 222, specifically, the comparison circuit 124B outputs a black-and-white changing signal to the subsequent arithmetic circuit 124D.

  On the other hand, in step 226, if the difference calculated in step 208 is less than the threshold ThD, the process proceeds to step 240. On the other hand, if the difference calculated in step 208 is greater than or equal to the threshold ThD, the process proceeds to step 228. In step 228, the maximum pixel value of the pixel values B, G, and R specified by the image data B, G, and R related to the pixel read after the target pixel among the pixels that are the calculation target in step 208. And the difference between the minimum pixel value and the minimum pixel value. In the next step 230, if the difference calculated in step 228 exceeds the threshold ThΔW, the process proceeds to step 240. If the difference calculated in step 228 is equal to or less than the threshold ThΔW, the process proceeds to step 232. To do.

  In step 232, the maximum pixel of the pixel values B, G, and R specified by the image data B, G, and R related to the pixel read before the target pixel among the pixels that are the calculation target in step 208 above. The difference between the value and the minimum pixel value is calculated. In the next step 234, if the difference calculated in step 232 exceeds the threshold ThΔB, the process proceeds to step 240. On the other hand, if the difference calculated in step 232 is equal to or less than the threshold ThΔB, the process proceeds to step 236. To do.

  In step 236, a black-and-white changing signal indicating that the target pixel specified in step 206 is a pixel existing in the middle of the change from black to white is output, and then the process proceeds to step 224. In step 236, more specifically, the comparison circuit 124B outputs a black-and-white changing signal to the subsequent arithmetic circuit 124D.

  On the other hand, in steps 238 and 240, the image data B, G, and R of the target pixel designated in step 206 are output. In steps 238 and 240, specifically, the comparison circuit 124B outputs the image data B, G, and R to the subsequent arithmetic circuit 124D.

  On the other hand, in step 224, color misregistration detection processing is executed. FIG. 8 shows an example of a specific process flow of the color misregistration detection process. In step 224A of FIG. 8, the difference between the maximum pixel value and the minimum pixel value of the pixel values B, G, R specified by the image data B, G, R related to the target pixel specified in step 206 is calculated. After the calculation, the process proceeds to step 224B. In step 224B, the color misregistration detection process is terminated when the difference calculated in step 224A is less than the threshold ThC. On the other hand, if the difference calculated in step 224A is greater than or equal to the threshold ThC, the process proceeds to step 224C. .

In step 224C, the pixel value specified by the image data B, G, and R relating to the target pixel specified in step 206 is selected from the maximum pixel value and the minimum pixel value that are the calculation source of the difference in step 224A. After identifying the one having the larger difference from the intermediate pixel value among B, G, and R, the process proceeds to step 224D. In addition, when the difference with the intermediate pixel value is not specified, that is, when there is no difference with the intermediate pixel value, the predetermined one is adopted. In the present embodiment, the maximum pixel value is adopted.
In step 224D, when the minimum pixel value of the maximum pixel value and the minimum pixel value that are the source of the difference in step 224A is specified in step 224C, the process proceeds to step 224J, while step 224C is performed. When the maximum pixel value of the maximum pixel value and the minimum pixel value that are used as the calculation source of the difference in step 224A is specified, the process proceeds to step 224E.

  In step 224E, among the pixel values B, G, and R specified by the image data B, G, and R related to the target pixel specified in step 206 and the maximum pixel value that is the source of the difference in step 224A. When the difference from the intermediate pixel value exceeds a predetermined threshold value, the process proceeds to step 224F, and when it is equal to or less than the threshold value, the color misregistration detection process ends.

  In step 224F, a color misregistration detection signal indicating that color misregistration has been detected for the target pixel specified in step 206 is output. Specifically, the comparison circuit 124B outputs a color misregistration detection signal to the subsequent arithmetic circuit 124D.

  In the next step 224G, correction is performed on the image data corresponding to the maximum pixel value from which the difference of step 224A is calculated among the image data B, G, and R related to the target pixel specified in step 206. After adding specific data specifying the target image data, the process proceeds to step 224H, and after outputting the image data B, G, R relating to the target pixel specified in step 206, the color misregistration detection process Exit. In step 224H, specifically, the comparison circuit 1214B outputs the image data B, G, and R to the subsequent arithmetic circuit 124D.

  On the other hand, in step 224J, pixel values B, G, R specified by the minimum pixel value that is the source of the difference in step 224A and the image data B, G, R relating to the target pixel specified in step 206 are described. If the difference from the intermediate pixel value exceeds a predetermined threshold value, the process proceeds to step 224K. If the difference is equal to or smaller than the threshold value, the color misregistration detection process is terminated.

  In step 224K, a color misregistration detection signal indicating that color misregistration has been detected for the target pixel specified in step 206 is output. Specifically, the comparison circuit 124B outputs a color misregistration detection signal to the subsequent arithmetic circuit 124D.

  In the next step 224L, correction is performed on the image data corresponding to the minimum pixel value from which the difference of step 224A is calculated among the image data B, G, and R related to the target pixel specified in step 206. After assigning specific data that identifies the target image data, the process proceeds to step 224H.

  When the processing of step 224 is executed as described above, the routine proceeds to step 226 as shown in FIG. In step 226, if all the image data B, G, R obtained by reading the image recording area of the document in the speed change prediction period α is not input, the process returns to step 200, while the speed change described above. When all the image data B, G, and R obtained by reading the image recording area of the document are input during the prediction period α, the achromatic / color misregistration detection process is terminated.

  FIG. 10 shows a method for identifying the change point of the achromatic color region used in the achromatic color / color shift detection process (whether the target pixel is a pixel in the middle of the change from the white color region to the black color region, or the change from the black color region to the white color region). It is explanatory drawing for demonstrating the method of specifying whether it is a pixel in the middle. In the present embodiment, as shown in FIG. 10, when the pixel at position “0” in the transport direction SS in the document is the target pixel, the pixel at position “−3” (read before the position “0”) is read. Pixel) and the pixel at the position “+1” (the pixel read after the position “0”) are used to change the target pixel from the white region to the black region. Whether the pixel is a pixel in the middle of a change from a black region to a white region is specified. In this case, for example, when all of the following conditions 1-a to 4-a are satisfied, the target pixel is specified as a pixel that is in the process of changing from the white region to the black region. The conditions 1-a to 4-a are listed below.

  Condition 1-a: Pixel value G (VDTG [-3]) specified by image data G at position "-3" from pixel value G (VDTG [+1]) specified by image data G at position "+1" The value (delta1) obtained by subtracting 0 is a value of 0 or more.

  Condition 2-a: a condition that delta1 is greater than or equal to the threshold ThD.

  Condition 3-a: The difference (WDLT) between the maximum pixel value and the minimum pixel value among the pixel values B, G, R specified by the image data B, G, R at the position “−3” is equal to or less than the threshold ThΔW. There is a condition.

  Condition 4-a: The difference (BDLT) between the maximum pixel value and the minimum pixel value among the pixel values B, G, R specified by the image data B, G, R at the position “+1” is equal to or less than the threshold ThΔB. , And conditions.

  On the other hand, when all of the following conditions 1-b to 4-b are satisfied, the target pixel is specified as a pixel that is in the process of changing from the black region to the white region. The conditions 1-b to 4-b are listed below.

  Condition 1-b: a condition that a value (delta2) obtained by subtracting VDTG [+1] from VDTG [-3] is a value of 0 or more.

  Condition 2-b: a condition that delta2 is equal to or greater than a threshold ThD.

  Condition 3-b: The difference (WDLT) between the maximum pixel value and the minimum pixel value among the pixel values B, G, R specified by the image data B, G, R at the position “+1” is equal to or less than the threshold ThΔW. , And conditions.

  Condition 4-b: The difference (BDLT) between the maximum pixel value and the minimum pixel value among the pixel values B, G, R specified by the image data B, G, R at the position “−3” is equal to or less than the threshold ThΔB. There is a condition.

  When the pixel at the position “0” is the target pixel, the pixel at the position “−2” and the position “+2” are not limited to the comparison with the pixel at the position “−3” and the pixel at the position “+1”. Or a comparison with the pixel at position “−1” and the pixel at position “+3” may be applied. In this way, comparison may be made with respect to pixels that are separated by a predetermined number of pixels across the pixel of interest. Further, in the example shown in FIG. 10, pixels that are separated by 4 pixels are targeted, but “4 pixels” is merely an example, and it is needless to say that the number of other pixels may be used. Yes.

  FIG. 11 is a graph showing an example of the relationship between the density value of each color and the position in the transport direction SS for explaining the color misregistration detection method employed in the color misregistration detection process. In the present embodiment, as shown in FIG. 11, the pixel at the position “3” in the document transport direction SS is white, and the pixel read after four pixels (the position “7” in the document transport direction SS) Pixel) is black (condition 1-c), and the difference between the maximum pixel value and the minimum pixel value of the image values B, G, R in each of the pixels at positions “4” to “6” is A condition (condition 2-c) that the threshold value is ThC or more, a difference between a maximum pixel value (pixel value B in the example shown in FIG. 11) and an intermediate pixel value (pixel value G in the example shown in FIG. 11), and The condition that any one of the differences between the minimum pixel value (pixel value R in the example shown in FIG. 11) and the intermediate pixel value (pixel value G in the example shown in FIG. 11) exceeds a predetermined threshold. When all the conditions 1-c to 3-c of (Condition 3-c) are satisfied, it is determined that a color shift has occurred between the achromatic regions That. In the example shown in FIG. 11, the change from the white area to the black area is illustrated, but the change from the black area to the white area is also configured to correspond to the color misregistration detection method shown in FIG. The color misregistration detection method is applied.

  Next, the color misregistration correction process will be described with reference to FIG. FIG. 12 is a flowchart showing an example of the color misregistration correction process executed by the arithmetic circuit 124D.

  In step 250 of FIG. 12, after waiting for input of the image data B, G, R output in step 238, step 240, or step 224H of the achromatic color / color misregistration detection process, the process proceeds to step 252. In step 252, when the color misregistration detection signal is not input, the process proceeds to step 268. On the other hand, when the color misregistration detection signal is input, the process proceeds to step 254. In step 254, the process proceeds to step 268 when the black-and-white change signal or black-and-white change signal is not input, while the process proceeds to step 256 when the black-and-white change signal or black-and-white change signal is input.

  In step 256, the process proceeds to step 258 when the black and white changing signal is input in step 254, while the process proceeds to step 272 when the black and white changing signal is input in step 254.

  In step 258, the image data B, G, R input in step 250 includes image data to which specific data (specific data for specifying image data of the maximum pixel value) is added in step 224G. In this case, the process proceeds to step 260. On the other hand, the image data B, G, R input in step 250 is given the specific data (specific data for specifying the image data having the minimum pixel value) in step 224L. Is included, the process proceeds to step 270.

  In step 260, the image data to which the specific data is added is selected from the image data B, G, R related to the target pixel specified in step 206 (the image data B, G, R input in step 250). In addition to the acquisition, the image data of the color of the image data to which the specific data is assigned is acquired from the image data holding circuit 124A among the image data B, G, R related to the pixel read before the target pixel. . In this case, the image data B, G, and R related to the pixel read one pixel before is applied as the image data B, G, and R related to the pixel read before the target pixel. However, the present invention is not limited to this, and image data B, G, and R relating to pixels read a plurality of pixels before the target pixel may be applied.

  In the next step 262, a plurality of sets (here, 5 sets as an example) of interpolation coefficients (predetermined coefficients whose sum is “1”) are acquired from the interpolation coefficient memory 124E, and then the process proceeds to step 264. In step 264, two-point interpolation is performed on the image data acquired in step 260 or step 270 described later using the plurality of sets of interpolation coefficients acquired in step 262 for each set, and then the process proceeds to step 266. To do. In step 266, among the image data (interpolated image data) for each set of interpolation coefficients obtained by performing the two-point interpolation in step 264, the image data B relating to the target pixel specified in step 206 is described. Image data (for example, image data B) for specifying a pixel value having the smallest difference from the intermediate pixel value among the pixel values B, G, and R specified by G and R, and image data for one pixel together with this image data After outputting the image data (for example, image data G and R) constituting each set, the process proceeds to step 268.

  In step 270, the image data to which the specific data is assigned is selected from the image data B, G, R related to the target pixel specified in step 206 (the image data B, G, R input in step 250). After obtaining the image data of the color of the image data to which the specific data is given from the image data holding circuit 124A among the image data B, G, R related to the pixel read after the target pixel. The process proceeds to step 262. Here, the image data B, G, and R related to the pixel read after one pixel are applied as the image data B, G, and R related to the pixel read after the target pixel. However, the image data B, G, and R relating to pixels read after a plurality of pixels after the target pixel may be applied.

  On the other hand, in step 272, the image data B, G, R input in step 250 includes image data to which specific data (specific data for specifying image data with the maximum pixel value) is added in step 224G. If the image data B, G, R input in step 250, the specific data (specific data specifying the image data of the minimum pixel value) is added in step 224L. If image data is included, the process proceeds to step 276.

  In step 274, the image data to which the specific data is assigned is selected from the image data B, G, R related to the target pixel specified in step 206 (the image data B, G, R input in step 250). After obtaining the image data of the color of the image data to which the specific data is given from the image data holding circuit 124A among the image data B, G, R related to the pixel read after the target pixel. The process proceeds to step 262. Here, the image data B, G, and R related to the pixel read after one pixel are applied as the image data B, G, and R related to the pixel read after the target pixel. However, the image data B, G, and R relating to pixels read after a plurality of pixels after the target pixel may be applied.

  In step 276, the image data to which the specific data is assigned is selected from the image data B, G, R related to the target pixel specified in step 206 (the image data B, G, R input in step 250). In addition to the acquisition, the image data of the color of the image data to which the specific data is assigned is acquired from the image data holding circuit 124A among the image data B, G, R related to the pixel read before the target pixel. . In this case, the image data B, G, and R related to the pixel read one pixel before is applied as the image data B, G, and R related to the pixel read before the target pixel. However, the present invention is not limited to this, and image data B, G, and R relating to pixels read a plurality of pixels before the target pixel may be applied.

  In step 268, when all the obtained image data B, G, R read in the above-described speed change prediction period α is not input, the process returns to step 250, but is read in the above-described speed change prediction period α. When all the obtained image data B, G, and R are input, the color misregistration correction process is terminated.

  FIG. 13 is a graph showing an example of the relationship between the density value of each color and the position in the transport direction SS for explaining the correction method using two-point interpolation employed in the color misregistration correction process. In the example shown in FIG. 13, a color shift occurs in the middle of the change from the white area to the black area, and the pixel in the middle of the change is the correction target pixel. The correction target pixel mentioned here specifically refers to a pixel corresponding to the image data to which the specific data is added in step 224G or step 224L. In FIG. 13, as the correction target pixels, a pixel at a position “4” in the transport direction SS on the document and a pixel at a position “6” in the transport direction SS on the document are illustrated.

  In the example illustrated in FIG. 13, a pixel value Bm that is the maximum pixel value of the correction target pixel at the position “4” and a pixel that is read one pixel ahead of the correction target pixel (a pixel at the position “3”). The value Bm-1 is used to correct the pixel value Bm by interpolation between two points. That is, the arithmetic circuit 124D obtains a plurality of sets of predetermined interpolation coefficients K1 and K2 from the interpolation coefficient memory 124E, and sets the value obtained by multiplying the pixel value Bm by the interpolation coefficient K1 and the interpolation coefficient K2 for each group. The sum with the value obtained by multiplying the value Bm-1 is calculated. Of the sums calculated in this way, the one closest to the pixel value Gm, which is the intermediate pixel value of the correction target pixel at the position “4”, is adopted as the final corrected pixel value Bm.

  In the example illustrated in FIG. 13, the pixel value Rn that is the minimum pixel value of the correction target pixel at the position “6” and the pixel read after one pixel of the correction target pixel (the pixel at the position “7”) The pixel value Rn + 1 is used to correct the pixel value Rn by interpolation between two points. That is, the arithmetic circuit 124D obtains a plurality of sets of predetermined interpolation coefficients K1 and K2 from the interpolation coefficient memory 124E, and obtains a value obtained by multiplying the pixel value Rn by the interpolation coefficient K1 and the interpolation coefficient K2 for each group. The sum of the value obtained by multiplying the value Rn + 1 is calculated. Of the sums calculated in this way, the pixel value Rn closest to the pixel value Gn, which is the intermediate pixel value of the correction target pixel at the position “6”, is adopted as the final corrected pixel value Rn. In the example illustrated in FIG. 13, the change from the white region to the black region is illustrated, but the correction configured to correspond to the correction method illustrated in FIG. 13 also in the case of the change from the black region to the white region. The method is applied.

  As described above in detail, in the image processing apparatus 10 according to the present embodiment, the document to be conveyed and read is moved with respect to the light source 72 that emits light to the image recording area, and the image recording area The light reflected by the image recording area is received by the photodiode 19 to generate image data B, G, R for each received light amount, and the generated image data B, G, R Based on this, a boundary region between achromatic regions (in the middle of changing from black to white or in the middle of changing from white to black) is detected, and the detected boundary region is within a predetermined number of pixels (here, within three pixels as an example) ), And the density difference between the achromatic regions across the boundary region is equal to or greater than a predetermined value (here, threshold ThD as an example), and image data B, G, R corresponding to the pixels existing in the boundary region Of which the maximum signal level ( Shows that color misregistration has occurred when the difference between the maximum pixel value (as an example) and the minimum signal level (here, the minimum pixel value as an example) is equal to or greater than a predetermined threshold (here, threshold ThC as an example). Since a color misregistration occurrence signal (for example, a black and white conversion midway signal or a black change midway signal) is output, color misregistration between achromatic regions is detected with high accuracy.

  In addition, since point-to-point interpolation is performed using image signals that are correction targets related to pixels that exist in boundary regions between different achromatic regions, color misregistration between achromatic regions is corrected with high accuracy.

  In addition, correction is performed by interpolating between the image signal that is the correction target related to the pixel existing in the boundary region between different achromatic regions and the image signal generated one pixel ahead or after this image signal. Since the target image signal is corrected, color misregistration between achromatic regions is corrected with higher accuracy than when the present configuration is not provided.

  In the above embodiment, after the maximum pixel value or the minimum pixel value is specified in the color misregistration detection process, the difference between the maximum pixel value and the intermediate pixel value or the difference between the minimum pixel value and the intermediate pixel value exceeds the threshold value. If the image data having the target pixel value determined to exceed the threshold is attached with specific data for specifying that it is a correction target. This is because it is effective in performing highly accurate correction. However, there may be a case where high-speed processing is required rather than performing such high-precision processing. In this case, either the maximum pixel value or the minimum pixel value may be treated as a correction target without calculating the difference between the maximum pixel value and the intermediate pixel value or the difference between the minimum pixel value and the intermediate pixel value. good. In this case, a process for calculating a difference between the maximum pixel value and the intermediate pixel value or a difference between the minimum pixel value and the intermediate pixel value and a process for comparing with the threshold value are omitted, so that a higher-speed process is realized.

  In the above embodiment, an example of a case where a document is conveyed has been described. However, the present invention is not limited to this, and a flat bed method may be used. In this case, the achromatic color / color misregistration detection process and the color misregistration correction process may be executed in a period predicted in advance as a period during which the moving speed of the light source 72 suddenly changes.

  In the above-described embodiment, an example in which the document is transported while the position of the light source 72 is fixed has been described. However, the light source 72 also moves in the transport direction SS while transporting the document. You may let them. In this case, instead of the speed change prediction period α, a period including both a time when the document transport speed suddenly changes and a time when the light source moving speed suddenly changes is applied. You may make it provide separately the period containing the time point which changes suddenly, and the period containing the time point where the moving speed of a light source changes suddenly so that it may not overlap.

  Further, in the above embodiment, the case where the image recording area where the ladder pattern is recorded on the original is set as the reading target is exemplified. However, an image other than the ladder pattern (for example, an image in which chromatic colors and achromatic colors are mixed or a An image recording area in which an image including no coloring is recorded may be set as a reading target.

  In the above embodiment, the point of reading the back side of the document is not mentioned. However, the achromatic color / color misregistration detection process and the color misregistration correction process function effectively even when the back side of the document is read. Needless to say.

  Further, in the above embodiment, the wording “white” and the wording “black” are used, but these words mean “0” and “255” of 256 gradations. The color is not limited and is determined by the white reference value and the black reference value described above. That is, the gradation values defining “white” and “black” may have a width or may not have a width.

  In the above-described embodiment, the CCD line sensors 82B, 82G, and 82R have been described as examples. However, the present invention is not limited to this. For example, each single blue array arranged in a state shifted along the transport direction SS is used. A photodiode, a green photodiode, and a red photodiode may be used. Further, a plurality of light receiving elements having different spectral sensitivities other than R, G, and B may be shifted along the transport direction SS. Thus, any form may be employed as long as a plurality of light receiving elements having different spectral sensitivities arranged in a state shifted in the transport direction SS are provided in units of one pixel.

12 Scanner 19 Photodiode 40 Document conveying section 42 Image reading section 82 Image reading sensor 82B Blue CCD line sensor 82G Green CCD line sensor 82R Red CCD line sensor 120 Shading correction circuit 122 Output delay circuit 124 Color shift detection / correction circuit 124B comparison circuit 124D arithmetic circuit

Claims (19)

Moving means for relatively moving at least one of a recording medium on which an image is recorded and a light source that emits light to an image recording area including the image in a predetermined direction;
A plurality of light receiving elements having different spectral sensitivities arranged in a state shifted in the predetermined direction are provided in units of one pixel, and light is irradiated to the image recording area during relative movement by the moving means, and the image recording area Generating means for receiving reflected light by the plurality of light receiving elements and generating an image signal corresponding to each received light amount;
Detecting means for detecting a boundary area between different achromatic areas in the image recording area based on the image signal generated by the generating means;
Specifying means for specifying a pixel having a color shift in the boundary region based on the image signal output from each of the plurality of light receiving elements corresponding to the pixels existing in the boundary region detected by the detection unit; ,
Among the image signals corresponding to each of the plurality of light receiving elements corresponding to the pixels specified by the specifying means for the area where the boundary area detected by the detecting means is changing from a white area to a black area, When the image signal having the maximum signal level is to be corrected, the color shift is corrected by interpolating the image signal and the corresponding image signal generated before the image signal between two points, When an image signal having a minimum signal level is targeted for correction among the image signals corresponding to each of the plurality of light receiving elements corresponding to the pixels specified by the specifying means, the image signal is generated after the image signal and the image signal. Correction means for correcting the color misregistration by interpolating between the corresponding image signals that have been performed,
An image reading apparatus.   The correction means further includes, for each of the plurality of light receiving elements corresponding to the pixels specified by the specifying means, about the area where the boundary area detected by the detection means is changing from a black area to a white area. When the image signal having the maximum signal level among the corresponding image signals is to be corrected, the color is obtained by interpolating the image signal and the corresponding image signal generated after the image signal between two points. When the image signal having the minimum signal level among the image signals corresponding to each of the plurality of light receiving elements corresponding to the pixels specified by the specifying unit is corrected, the image signal and the image signal are corrected. The image reading apparatus according to claim 1, wherein the color misregistration is corrected by interpolating between the corresponding image signals generated before the image signal between two points. Moving means for relatively moving at least one of a recording medium on which an image is recorded and a light source that emits light to an image recording area including the image in a predetermined direction;
A plurality of light receiving elements having different spectral sensitivities arranged in a state shifted in the predetermined direction are provided in units of one pixel, and light is irradiated to the image recording area during relative movement by the moving means, and the image recording area Generating means for receiving reflected light by the plurality of light receiving elements and generating an image signal corresponding to each received light amount;
Detecting means for detecting a boundary area between different achromatic areas in the image recording area based on the image signal generated by the generating means;
Specifying means for specifying a pixel having a color shift in the boundary region based on the image signal output from each of the plurality of light receiving elements corresponding to the pixels existing in the boundary region detected by the detection unit; ,
Among the image signals corresponding to each of the plurality of light receiving elements corresponding to the pixels specified by the specifying means for the area where the boundary area detected by the detecting means is changing from a black area to a white area, When an image signal having the maximum signal level is to be corrected, the color misregistration is corrected by interpolating between the image signal and the corresponding image signal generated after the image signal between the two points. When an image signal having a minimum signal level among the image signals corresponding to each of the plurality of light receiving elements corresponding to the pixels specified by the means is to be corrected, the image signal is generated prior to the image signal. Correction means for correcting the color misregistration by interpolating between the corresponding image signals that have been performed,
An image reading apparatus.   The correction unit further includes, for each of the plurality of light receiving elements corresponding to the pixel specified by the specifying unit, about the region where the boundary region detected by the detection unit is changing from a white region to a black region. Among the corresponding image signals, when an image signal having the maximum signal level is to be corrected, the image signal and the corresponding image signal generated prior to the image signal are interpolated between two points, thereby When an image signal having a minimum signal level among image signals corresponding to each of the plurality of light receiving elements corresponding to the pixels specified by the specifying unit is corrected, the image signal is corrected. The image reading apparatus according to claim 3, wherein the color misregistration is corrected by interpolating between the corresponding image signals generated after the image signal between two points. Moving means for relatively moving at least one of a recording medium on which an image is recorded and a light source that emits light to an image recording area including the image in a predetermined direction;
A plurality of light receiving elements having different spectral sensitivities arranged in a state shifted in the predetermined direction are provided in units of one pixel, and light is irradiated to the image recording area during relative movement by the moving means, and the image recording area Generating means for receiving reflected light by the plurality of light receiving elements and generating an image signal corresponding to each received light amount;
Detecting means for detecting a boundary area between different achromatic areas in the image recording area based on the image signal generated by the generating means;
Specifying means for specifying a pixel having a color shift in the boundary region based on the image signal output from each of the plurality of light receiving elements corresponding to the pixels existing in the boundary region detected by the detection unit; ,
Among the image signals corresponding to each of the plurality of light receiving elements corresponding to the pixels specified by the specifying unit, the image signal having the maximum signal level is to be corrected, and the boundary region detected by the detecting unit is In the case of a region in the middle of a change from a white region to a black region, the color is obtained by interpolating the image signal to be corrected and the corresponding image signal generated before the image signal between two points. The image signal having the maximum signal level among the image signals corresponding to each of the plurality of light receiving elements corresponding to the pixels specified by the specifying unit is corrected and detected by the detecting unit. In addition, when the boundary area is an area in the middle of a change from a black area to a white area, an image signal to be corrected and a corresponding before generated image signal And correcting means for correcting the color shift by the image signal interpolating between two points,
An image reading apparatus.   The correcting means further targets an image signal having a minimum signal level among the image signals corresponding to each of the plurality of light receiving elements corresponding to the pixels specified by the specifying means, and the detecting means When the detected boundary region is a region in the middle of a change from a white region to a black region, the image signal to be corrected and the corresponding image signal generated after the image signal are The color shift is corrected by interpolation, and an image signal having a minimum signal level among image signals corresponding to each of the plurality of light receiving elements corresponding to the pixels specified by the specifying unit is to be corrected, and When the boundary area detected by the detection means is an area in the middle of a change from a black area to a white area, the image signal to be corrected and the image signal before the image signal The apparatus according to said image signal generated corresponding the to claim 5 for correcting the color shift by interpolating between two points. Moving means for relatively moving at least one of a recording medium on which an image is recorded and a light source that emits light to an image recording area including the image in a predetermined direction;
A plurality of light receiving elements having different spectral sensitivities arranged in a state shifted in the predetermined direction are provided in units of one pixel, and light is irradiated to the image recording area during relative movement by the moving means, and the image recording area Generating means for receiving reflected light by the plurality of light receiving elements and generating an image signal corresponding to each received light amount;
Detecting means for detecting a boundary area between different achromatic areas in the image recording area based on the image signal generated by the generating means;
Specifying means for specifying a pixel having a color shift in the boundary region based on the image signal output from each of the plurality of light receiving elements corresponding to the pixels existing in the boundary region detected by the detection unit; ,
Among the image signals corresponding to each of the plurality of light receiving elements corresponding to the pixels specified by the specifying means, an image signal having a minimum signal level is to be corrected, and the boundary region detected by the detecting means is In the case of a region in the middle of a change from a white region to a black region, the color shift is performed by interpolating the image signal to be corrected and the corresponding image signal generated after the image signal between two points. The image signal having the minimum signal level among the image signals corresponding to each of the plurality of light receiving elements corresponding to the pixels specified by the specifying unit is corrected and detected by the detecting unit When the boundary region is a region in the middle of a change from a black region to a white region, the image signal to be corrected and a corresponding before-generated image signal And correcting means for correcting the color shift by the image signal interpolating between two points,
An image reading apparatus.   The correction means further targets an image signal having a maximum signal level among image signals corresponding to each of the plurality of light receiving elements corresponding to the pixels specified by the specifying means, and the detection means When the detected boundary region is a region in the middle of a change from a white region to a black region, two points of the image signal to be corrected and the corresponding image signal generated before the image signal are obtained. The color shift is corrected by interpolating, and the image signal having the maximum signal level among the image signals corresponding to each of the plurality of light receiving elements corresponding to the pixels specified by the specifying unit is to be corrected, In addition, when the boundary area detected by the detection unit is an area in the middle of a change from a black area to a white area, the image signal to be corrected and the image signal The apparatus according to said image signal corresponding generated to claim 7 for correcting the color shift by interpolating between two points.   9. The image reading apparatus according to claim 1, wherein the image signals to be interpolated between the two points are image signals generated adjacent to each other in time series. The correction means performs the interpolation between the two points using a plurality of sets of interpolation coefficients for each set,
Among the interpolation results obtained by performing the interpolation between the two points, an image signal having an intermediate signal level among image signals corresponding to each of the plurality of light receiving elements corresponding to the pixel specified by the specifying unit The image reading apparatus according to claim 1, wherein an interpolation result closest to the signal level is applied as a corrected image signal.   The specifying means has the boundary area detected by the detecting means within a predetermined number of pixels, and the density difference between the achromatic areas sandwiching the boundary area is not less than a predetermined value, and the boundary area Among the existing pixels, a pixel whose difference between the maximum signal level and the minimum signal level of the image signal output from each of the corresponding light receiving elements is equal to or greater than a predetermined color shift threshold is color-shifted. The image reading device according to claim 1, wherein the image reading device is specified as a pixel in which the occurrence of the error occurs.   The image reading apparatus according to claim 1, wherein the moving unit includes a conveying unit that conveys the recording medium so that the light of the light source is irradiated to the image recording area.   The detection means includes the image signal corresponding to an area irradiated with the light during a predetermined period as a period during which the conveyance speed of the recording medium conveyed by the conveyance means in the image recording area changes. The image reading device according to claim 12, wherein the boundary region is detected based on the image.   The generation unit is a line sensor in which the plurality of light receiving elements are arranged along the predetermined direction in units of one pixel and a plurality of sets are arranged in a direction intersecting the predetermined direction for each spectral sensitivity. The image reading apparatus according to any one of claims 1 to 13.   The detection means includes a maximum signal level and a minimum signal level among signal levels of the image signals corresponding to the plurality of light receiving elements related to the previous pixel, with respect to a pixel preceding the generation order of the image signal by a predetermined number of pixels. The absolute value of the difference from the signal level is within a predetermined white reference value as a value indicating white and within a predetermined black reference value as a value indicating black And the absolute value of the difference between the maximum signal level and the minimum signal level among the signal levels of each image signal corresponding to the plurality of light receiving elements related to the subsequent pixel is satisfied, When the other condition of the condition of being within the predetermined white reference value and the condition of being within the predetermined black reference value is satisfied, the pixel is sandwiched between the previous pixel and the subsequent pixel. The area is detected as the boundary area. The image reading apparatus according to any one of claims 1 to 14. A moving means for relatively moving at least one of a recording medium on which an image is recorded and a light source for irradiating light to an image recording area including the image in a predetermined direction, and a spectrum arranged in a state shifted in the predetermined direction A plurality of light receiving elements having different sensitivities are provided in units of one pixel, and light reflected on the image recording area is received by the plurality of light receiving elements during the relative movement by the moving means. Generating means for generating an image signal corresponding to each received light amount, and a computer for controlling the image reading apparatus,
Detecting means for detecting a boundary area between different achromatic areas in the image recording area based on the image signal generated by the generating means;
Specifying means for specifying a pixel in which color misregistration occurs in the boundary region based on the image signal output from each of the plurality of light receiving elements corresponding to the pixel existing in the boundary region detected by the detection unit;
And an image signal corresponding to each of the plurality of light receiving elements corresponding to the pixel specified by the specifying means for an area where the boundary area detected by the detecting means is changing from a white area to a black area. When the image signal having the maximum signal level is to be corrected, the color shift is corrected by interpolating between the image signal and the corresponding image signal generated before the image signal. When the image signal having the minimum signal level among the image signals corresponding to each of the plurality of light receiving elements corresponding to the pixel specified by the specifying unit is to be corrected, the image signal and the image signal A program for functioning as correction means for correcting the color shift by interpolating between the corresponding image signals generated later between two points. A moving means for relatively moving at least one of a recording medium on which an image is recorded and a light source for irradiating light to an image recording area including the image in a predetermined direction, and a spectrum arranged in a state shifted in the predetermined direction A plurality of light receiving elements having different sensitivities are provided in units of one pixel, and light reflected on the image recording area is received by the plurality of light receiving elements during the relative movement by the moving means. Generating means for generating an image signal corresponding to each received light amount, and a computer for controlling the image reading apparatus,
Detecting means for detecting a boundary area between different achromatic areas in the image recording area based on the image signal generated by the generating means;
Specifying means for specifying a pixel in which color misregistration occurs in the boundary region based on the image signal output from each of the plurality of light receiving elements corresponding to the pixel existing in the boundary region detected by the detection unit;
And an image signal corresponding to each of the plurality of light receiving elements corresponding to the pixel specified by the specifying unit with respect to a region in which the boundary region detected by the detecting unit is changing from a black region to a white region. Among them, when the image signal having the maximum signal level is to be corrected, the color shift is corrected by interpolating between the image signal and the corresponding image signal generated after the image signal, When an image signal having a minimum signal level among image signals corresponding to each of the plurality of light receiving elements corresponding to the pixels specified by the specifying unit is to be corrected, the image signal and the image signal are preceded. A program for functioning as a correcting means for correcting the color misregistration by interpolating between the corresponding image signals generated in (2). A moving means for relatively moving at least one of a recording medium on which an image is recorded and a light source for irradiating light to an image recording area including the image in a predetermined direction, and a spectrum arranged in a state shifted in the predetermined direction A plurality of light receiving elements having different sensitivities are provided in units of one pixel, and light reflected on the image recording area is received by the plurality of light receiving elements during the relative movement by the moving means. Generating means for generating an image signal corresponding to each received light amount, and a computer for controlling the image reading apparatus,
Detecting means for detecting a boundary area between different achromatic areas in the image recording area based on the image signal generated by the generating means;
Specifying means for specifying a pixel in which color misregistration occurs in the boundary region based on the image signal output from each of the plurality of light receiving elements corresponding to the pixel existing in the boundary region detected by the detection unit;
And the boundary detected by the detection means, with the image signal having the maximum signal level among the image signals corresponding to each of the plurality of light receiving elements corresponding to the pixels specified by the specifying means being corrected. When the region is a region in the middle of a change from a white region to a black region, interpolation is performed between the image signal to be corrected and the corresponding image signal generated before the image signal between two points. The color misregistration is corrected, an image signal having a maximum signal level among image signals corresponding to each of the plurality of light receiving elements corresponding to the pixels specified by the specifying unit is set as a correction target, and the detection unit When the detected boundary area is an area in the middle of a change from a black area to a white area, the image signal to be corrected and the correspondence generated after the image signal The image signal and a program for functioning as a correction means for correcting the color shift by interpolating between two points that. A moving means for relatively moving at least one of a recording medium on which an image is recorded and a light source for irradiating light to an image recording area including the image in a predetermined direction, and a spectrum arranged in a state shifted in the predetermined direction A plurality of light receiving elements having different sensitivities are provided in units of one pixel, and light reflected on the image recording area is received by the plurality of light receiving elements during the relative movement by the moving means. Generating means for generating an image signal corresponding to each received light amount, and a computer for controlling the image reading apparatus,
Detecting means for detecting a boundary area between different achromatic areas in the image recording area based on the image signal generated by the generating means;
Specifying means for specifying a pixel in which color misregistration occurs in the boundary region based on the image signal output from each of the plurality of light receiving elements corresponding to the pixel existing in the boundary region detected by the detection unit;
And the boundary detected by the detection unit, the correction target being an image signal having a minimum signal level among the image signals corresponding to each of the plurality of light receiving elements corresponding to the pixels specified by the specifying unit When the region is a region in the middle of a change from a white region to a black region, the image signal to be corrected and the corresponding image signal generated after the image signal are interpolated between two points, Corrects the color misregistration, detects the image signal having the minimum signal level from among the image signals corresponding to each of the plurality of light receiving elements corresponding to the pixels specified by the specifying means, and detects them by the detecting means. If the boundary area is an area in the middle of a change from a black area to a white area, the image signal to be corrected and the correspondence generated prior to the image signal The image signal and a program for functioning as a correction means for correcting the color shift by interpolating between two points that.

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