Correction pattern, image correction method, image processing device, and image reading device

Abstract

To provide a pattern for correction, an image correction method, an image processing device and an image reading device which can suitably connect an error of an image based on a deviation of an arrangement position of each image pick-up device in such a configuration that the image pick-up devices are arranged in the line shape.SOLUTION: An image reading device 10 includes an image reading unit 30 and a control unit 20 including a parameter generation processing part 102 and a correction processing part 108. The parameter generation processing part 102 generates parameter data 100 for correction on the basis of a read image for correction when the read image for correction including a code image extending in the direction intersecting the conveyance direction and reference images arrayed in the conveyance direction with respect to the code image is read by the image reading unit 30 as an image of an object. The correction processing part 108 corrects a reading object image on the basis of the parameter data 100 for correction when the reading object image different from the read image for correction is read by the image reading unit 30 as the image of the object.SELECTED DRAWING: Figure 9

Description

Technical Field

[0001] The present invention relates to an image reading device that reads an image of an object using a line sensor including a plurality of imaging elements, a correction pattern used therefor, an image correction method, and an image processing device.

Background Art

[0002] A contact image sensor (CIS) as exemplified in Patent Document 1 below generally includes a plurality of light-receiving IC chips as imaging elements. A plurality of photoelectric conversion elements such as photodiodes are arranged in a line on each light-receiving IC chip. Each light-receiving IC chip is arranged along the length direction on a long mounting substrate by a mounting device called a mounter.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, the imaging elements of such a line sensor may be displaced from their original arrangement positions on the substrate due to mounting errors during assembly or the like. Specifically, they may be displaced as if slightly rotated from the original arrangement position. Also, it is conceivable to improve the resolution of the line sensor by displacing the imaging elements so as to be inclined.

[0005] Thus, when the arrangement position of the imaging elements is displaced, a read image in which the image in at least a part of the region is inclined with respect to the original read image is obtained.

[0006] The present invention has been made in view of the above circumstances, and aims to provide a correction pattern, an image correction method, an image processing device, and an image reading device that can suitably correct image errors caused by misalignment of the placement positions of each image sensor in a configuration in which multiple image sensors are arranged in a line. [Means for solving the problem]

[0007] (1) The correction pattern according to the present invention is a correction pattern used in a line sensor that reads images of objects moving relatively along the transport direction using a plurality of image sensors arranged in a line, and comprises a code image extending in a direction intersecting the transport direction, and a correction reading image including a reference image aligned in the transport direction with respect to the code image.

[0008] With this configuration, errors in the image to be read due to misalignment of the placement of each image sensor can be suitably corrected based on the corrective read image.

[0009] (2) The code image may be composed of multiple lines extending in a direction intersecting the transport direction, arranged at intervals in the transport direction. In this case, the thickness and spacing of the lines may change along the direction intersecting the transport direction.

[0010] With this configuration, errors in the image to be read due to misalignment of the placement of each image sensor can be suitably corrected using a code image in which one-dimensional codes, which can be uniquely quantified by a combination of line thickness and spacing, are arranged in a direction intersecting the transport direction. The code image has a barcode formed by arranging multiple bars that extend in a direction intersecting the transport direction at intervals in the transport direction, and it can also be said that it is formed by arranging different barcodes along a direction intersecting the transport direction.

[0011] (3) The code image may be composed of a plurality of code regions having a width less than or equal to the width of each image sensor in a direction intersecting the transport direction, arranged in a direction intersecting the transport direction.

[0012] With this configuration, errors in the image to be read due to misalignment of the position of each image sensor can be effectively corrected using a code image in which the code regions associated with each image sensor are arranged in a direction intersecting the transport direction.

[0013] (4) The image correction method according to the present invention is an image correction method using the correction pattern, and includes a parameter generation step and a correction step. In the parameter generation step, when the correction reading image is read by the line sensor as an image of the object, correction parameters are generated based on the correction reading image. In the correction step, when a reading image different from the correction reading image is read by the line sensor as an image of the object, the reading image is corrected based on the correction parameters.

[0014] With this configuration, correction parameters corresponding to each image sensor are generated based on the corrected read image, and errors in the read image due to misalignment of the placement of each image sensor can be suitably corrected based on these correction parameters.

[0015] (5) The image processing apparatus according to the present invention corrects the image to be read using the image correction method.

[0016] With this configuration, it is possible to provide an image processing device that generates correction parameters corresponding to each image sensor based on a correction-read image, and then suitably corrects errors in the image to be read based on the misalignment of the placement of each image sensor.

[0017] (6) The image reading device according to the present invention comprises a line sensor, a parameter generation processing unit, and a correction processing unit. The line sensor reads images of objects moving relatively along the transport direction using a plurality of image sensors arranged in a line. The parameter generation processing unit generates correction parameters based on the correction reading image when the correction reading image is read by the line sensor as an image of the object. The correction processing unit corrects the image to be read based on the correction parameters when an image to be read that is different from the correction reading image is read by the line sensor as an image of the object. The parameter generation processing unit includes a region identification processing unit and a parameter calculation processing unit. The region identification processing unit identifies regions in the reference image corresponding to each image sensor based on the code image. The parameter calculation processing unit calculates the correction parameters corresponding to each image sensor based on the reference image of the regions corresponding to each image sensor identified by the region identification processing unit.

[0018] With this configuration, correction parameters corresponding to each image sensor are generated based on the corrected read image, and errors in the read image due to misalignment of the placement of each image sensor can be suitably corrected based on these correction parameters.

[0019] (7) The reference image may include a matrix image.

[0020] With this configuration, errors based on the misalignment of the placement of each image sensor can be easily detected based on the elements that make up the matrix image.

[0021] (8) The matrix image may include a grid-like image having multiple lines that intersect each other.

[0022] With this configuration, errors based on the misalignment of the placement of each image sensor can be easily detected based on the intersection points of the straight lines that constitute the matrix image.

[0023] (9) The matrix image may include an image in which a plurality of dots are arranged.

[0024] According to such a configuration, based on the dots that are elements constituting the matrix image, it is possible to easily detect an error based on the deviation of the arrangement position of each imaging element.

[0025] (10) The parameter calculation processing unit may calculate the correction parameter corresponding to each imaging element based on at least three feature points in the reference image.

[0026] According to such a configuration, it is possible to calculate the correction parameter only based on at least three feature points in the reference image.

[0027] (11) The at least three feature points may include a first feature point, a second feature point, and a third feature point that is not on the straight line connecting the first feature point and the second feature point.

[0028] According to such a configuration, it is possible to calculate the correction parameter based on three feature points that are not arranged on a straight line in the reference image. Also, when calculating the correction parameter only based on three feature points, it is possible to calculate the correction parameter efficiently.

[0029] (12) The image reading device may include a plurality of the line sensors. The main scanning direction of each line sensor may extend in a different direction with respect to the conveyance direction.

[0030] According to such a configuration, while using a plurality of line sensors, generating a correction parameter corresponding to each imaging element based on the correction reading image, and preferably correcting an error of the read image based on the deviation of the arrangement position of each imaging element based on this correction parameter.

[0031] (13) The line sensor may have an elongated shape along a longitudinal direction intersecting the transport direction, and the plurality of image sensors, which are inclined with respect to the longitudinal direction, may be arranged in a line along the longitudinal direction.

[0032] With this configuration, multiple image sensors tilted with respect to the longitudinal direction of the line sensor are arranged in a line along that longitudinal direction, and correction parameters corresponding to each image sensor are generated based on the correction read image. Based on these correction parameters, errors in the read image caused by misalignment of the position of each image sensor can be suitably corrected.

[0033] (14) The line sensors may have an elongated shape along a longitudinal direction intersecting the transport direction, and multiple sensors may be arranged in a row along the longitudinal direction.

[0034] With this configuration, multiple line sensors are arranged in a line along their longitudinal direction, and correction parameters corresponding to each image sensor are generated based on the correction reading image. Based on these correction parameters, errors in the image to be read due to misalignment of the position of each image sensor can be suitably corrected.

[0035] (15) The correction processing unit may correct the tilt of the image to be read based on the correction parameters.

[0036] With this configuration, the tilt of the image to be read, which is caused by the misalignment of the placement of each image sensor, can be suitably corrected based on correction parameters corresponding to each image sensor.

[0037] (16) The correction processing unit may correct the deviation of the image to be read along the transport direction based on the correction parameters.

[0038] With this configuration, errors in the image being read, caused by misalignment along the transport direction of each image sensor, can be corrected based on correction parameters corresponding to each image sensor.

[0039] (17) The correction processing unit may correct the ratio of the dimension of the image to be read along the transport direction to the dimension along the direction intersecting the transport direction based on the correction parameters.

[0040] With this configuration, the aspect ratio of the image to be read can be corrected based on correction parameters corresponding to each image sensor. [Effects of the Invention]

[0041] According to the present invention, in a configuration in which multiple image sensors are arranged in a line, image errors due to misalignment of the position of each image sensor can be suitably corrected. [Brief explanation of the drawing]

[0042] [Figure 1] This block diagram shows an example of the electrical configuration of the image reading device according to this embodiment. [Figure 2] This is a schematic cross-sectional view showing an example of the configuration of the image reading unit in this embodiment. [Figure 3] This is a schematic cross-sectional view showing some other examples of the configuration of the image reading unit in this embodiment. [Figure 4] This is a schematic diagram showing an example of the configuration of the light-receiving unit in this embodiment. [Figure 5] This is a schematic diagram showing an example of a correction reading image included in the correction pattern of this embodiment. [Figure 6] This is a diagram illustrating the process of generating correction parameters. [Figure 7] This is a diagram illustrating the process of generating correction parameters. [Figure 8] This is a diagram illustrating the method of correcting the image being read. [Figure 9] This is a block diagram showing an example of the functional configuration of the image reading device of this embodiment. [Figure 10] This is a schematic diagram showing another example of the configuration of the light-receiving unit in this embodiment. [Figure 11]This is a schematic diagram showing yet another example of the configuration of the light-receiving unit in this embodiment. [Modes for carrying out the invention]

[0043] 1. Electrical configuration of the image reading device Figure 1 is a block diagram showing an example of the electrical configuration of the image reading device 10 in this embodiment. As shown in Figure 1, the image reading device 10 includes a control unit 20 and an image reading unit 30, each of which is electrically connected via a bus 28. The control unit 20 functions as an image processing device that performs processing for correcting images.

[0044] Furthermore, the control unit 20 includes a CPU (Central Processing Unit) 22, RAM (Random Access Memory) 24, and a storage unit 26.

[0045] The CPU 22 is responsible for the overall control of the image reading device 10. The RAM 24 is used as the work area and buffer area for the CPU 22.

[0046] The storage unit 26 is the main memory of the image reading device 10, and non-volatile memory such as an HDD (Hard Disk Drive) and EEPROM (Electrically Erasable Programmable Read Only Memory) is used. The storage unit 26 may also be configured to include RAM 24.

[0047] The memory unit 26 stores data related to the control program used by the CPU 22 to control the operation of each component of the image reading device 10, data related to various images, and execution data necessary for executing the control program.

[0048] The image reading unit 30 is a line sensor. In this embodiment, the case in which a contact image sensor (CIS) is used as the image reading unit 30 will be explained as an example, but the image reading unit 30 is not particularly limited.

[0049] 2. Overall configuration of the image reading unit Figure 2 is a schematic cross-sectional view showing an example of the configuration of the image reading unit 30 in this embodiment. Note that the image reading unit 30 shown in Figure 2 has an elongated shape that extends in a direction perpendicular to the transport direction (Y direction), so the longitudinal direction of the image reading unit 30 is the same as the X direction.

[0050] The image reading unit 30 reads the image of an object T being transported along the Y direction. In other words, the Y direction can also be said to be the reading direction of the object T. Paper sheets can be used as an example of the object T, but it is not limited to this, and it is possible to read the image of any object T.

[0051] The image reading unit 30 comprises a housing 32, a line illumination light source 34 for illuminating the object T, a lens array 38 for guiding the light emitted from the line illumination light source 34 toward the focal plane 36 and reflected by the object T, and a light receiving unit 42 mounted on a substrate 40 for receiving the light that has passed through the lens array 38. The object T is transported in the Y direction along the focal plane 36. These housing 32, line illumination light source 34, lens array 38, and light receiving unit 42 extend in the X direction, and Figure 1 shows a cross-section perpendicular to the X direction.

[0052] The line illumination light source 34 is provided with a transparent light guide 44 extending along the X direction. Each outer side of the light guide 44 is held by a cover member 46. A light source (not shown) is provided at one or both ends of the light guide 44 in the X direction, and light entering the light guide 44 from the light source is diffused by the light diffusion pattern P and emitted from the side of the light guide 44 that is not covered by the cover member 46.

[0053] Light emitted from the line illumination light source 34 passes through the protective glass 48 and is focused at the focal plane 36. The protective glass 48 is not strictly necessary and can be omitted, but it is desirable to install it to protect the line illumination light source 34 and lens array 38 from scattering of dust and scratches during use. The material of the protective glass 48 can be any material that transmits the light emitted from the line illumination light source 34, such as a transparent resin such as acrylic resin or cycloolefin resin, or white glass or borosilicate glass.

[0054] A light source substrate 50 for fixing the light source unit is installed opposite the bottom surface of the line lighting light source 34. This light source substrate 50 is a thin insulating board made of phenol, glass epoxy, etc., and a wiring pattern made of copper foil is formed on its back surface. By inserting the terminals of the light source unit into holes formed at various locations on the light source substrate 50 and joining them to the wiring pattern on the back surface of the light source substrate 50 with solder or the like, the light source unit can be mounted and fixed to the light source substrate 50, and power can be supplied to the light source unit from a predetermined drive power supply (not shown) through the wiring pattern on the back surface of the substrate.

[0055] The lens array 38 is an optical element that forms an image of light reflected from the object T onto the light-receiving unit 42, and can be composed of a rod lens array. In this embodiment, the magnification of the lens array 38 is set to 1 (erect). An ultraviolet light blocking filter film 47 may be provided at any position from the focal plane 36 to the light-receiving unit 42 to block ultraviolet light by reflecting or absorbing it, so that ultraviolet light does not enter the light-receiving unit 42.

[0056] The light-receiving unit 42 is mounted on the substrate 40 and includes multiple photoelectric conversion elements that receive reflected light from the object T and read an image by photoelectric conversion. The material and structure of the photoelectric conversion elements are not particularly limited and may include photodiodes or phototransistors made of amorphous silicon, crystalline silicon, CdS, or CdSe. In this embodiment, a light-receiving IC (Integrated Circuit) chip in which multiple photoelectric conversion elements are arranged in a straight line in the X direction is arranged along the X direction on a long substrate 40. In addition, if necessary, electrical circuits such as drive circuits or amplification circuits, A / D converters, or connectors for extracting signals to the outside can also be mounted on the substrate 40.

[0057] Figure 2 illustrates a reflective image reading unit 30 that emits light from a line illumination light source 34 toward an object T and receives the light reflected by the object T. However, this embodiment is not limited to a reflective image reading unit 30. Figure 3 is a schematic cross-sectional view showing some other examples of the configuration of the image reading unit 30 in this embodiment. In the transmissive image reading unit 30 shown in Figure 3, the line illumination light source 34 is positioned on the opposite side of the light receiving unit 42 from the focal plane 36, and the light emitted from the line illumination light source 34 toward the object T and transmitted through the object T is received. In this case, the only difference from the arrangement in Figure 2 is that the position of the line illumination light source 34 is below the focal plane 36, and the configuration of the line illumination light source 34 itself is the same as the configuration in Figure 2.

[0058] 3. Configuration of the light-receiving section Figure 4 is a schematic diagram showing an example of the configuration of the light-receiving unit 42 in this embodiment. Figure 4 shows a bottom view of the light-receiving unit 42 and the substrate 40 as viewed along the Z direction.

[0059] The light-receiving unit 42 is equipped with multiple light-receiving IC chips 52 that serve as image sensors. The multiple light-receiving IC chips 52 are arranged in a line along the X direction. Here, "line-like" refers to a configuration in which the longitudinal direction of each light-receiving IC chip 52 is the same and they are arranged in a line along the X direction.

[0060] In the example shown in Figure 4, multiple light-receiving IC chips 52 are arranged in a straight line along the X direction. In the example shown in Figure 4, the longitudinal direction of the light-receiving IC chips 52 coincides with the longitudinal direction of the image reading unit 30, and therefore the main scanning direction of the image reading unit 30 coincides with the longitudinal direction.

[0061] With this image reading unit 30, the image of the object T being transported along the Y direction can be read by multiple light-receiving IC chips 52 arranged in a line.

[0062] In the explanation of Figures 2-4, the longitudinal direction of the image reading unit 30 is the same as the X direction, so the various components of the image reading unit 30 extend in the X direction or are arranged in the X direction. Specifically, the various components are provided along the longitudinal direction of the image reading unit 30.

[0063] 4. Example of a reading image for correction In this embodiment, if necessary, the image reading unit 30 reads a correction reading image 54 (see Figure 5) to generate correction parameters. When reading an image to be read (the actual object to be read) that is different from the correction reading image 54, correction processing is performed based on the pre-generated correction parameters.

[0064] Figure 5 is a schematic diagram showing an example of a correction reading image 54 included in the correction pattern of this embodiment. Figure 5 is also a schematic diagram showing the surroundings of the image reading unit 30 and the correction reading image 54. In the example shown in Figure 5, a black correction reading image 54 is displayed on a plain (white) solid-colored surface. By transporting a sheet with such a correction reading image 54 along the focal plane 36 as the object T and reading the correction reading image 54, correction parameters can be generated.

[0065] The correction reading image 54 includes a code image 56 and a reference image 58. The code image 56 extends in a direction intersecting the Y direction, specifically in a direction orthogonal to it, and the reference image 58 is aligned with the code image 56 in the Y direction.

[0066] The code image 56 is an image that makes it possible to identify each region of the reference image 58 read by each light-receiving IC chip 52. In the example shown in Figure 5, the code image 56 is formed from a plurality of one-dimensional code regions 60 that are readable along the Y direction, and each of the one-dimensional code regions 60 is arranged continuously in a direction perpendicular to the Y direction. Specifically, the code image 56 is composed of multiple lines (bars) extending in the X direction arranged at intervals in the Y direction, and the thickness and spacing of the lines (bars) change along the X direction. Furthermore, the code image 56 is composed of a plurality of one-dimensional code regions 60 having a width less than or equal to the width of each light-receiving IC chip 52 along the X direction, arranged along the X direction.

[0067] For example, as shown in Figure 5, if the image reading unit 30 reads the correction reading image 54 along the Y direction, then in the reference image 58, the regions read by the light-receiving IC chips 52 at both ends in the X direction are identified as regions S1 and S16 based on the one-dimensional code regions 60 at both ends in the X direction.

[0068] In other words, the code image 56 allows us to identify the region in the reference image 58 corresponding to each light-receiving IC chip 52. In particular, as will be described later, when the light-receiving IC chips 52 are tilted, and multiple light-receiving IC chips 52 with different tilts exist simultaneously, and there is a large overlap of these light-receiving IC chips 52 in the Y direction, or when the image data read by each light-receiving IC chip 52 is output in an order different from the arrangement order of each light-receiving IC chip 52, the code image 56 has a great advantage in identifying the region of the reference image 58. Note that the code image 56 is not particularly limited as long as it can identify the region of the reference image 58 read by each light-receiving IC chip 52, as described above.

[0069] The reference image 58 is an image containing at least three feature points for each region identified by the code image 56. Specifically, the reference image 58 is an image containing, in addition to the above at least three feature points, a first feature point, a second feature point, and a third feature point that is not on the line connecting the first and second feature points. As the reference image 58, for example, a matrix image such as the one shown in Figure 5 can be used. A matrix image is composed of multiple images arranged in a matrix, and in the example in Figure 5, multiple rectangular images are arranged in a grid. As a result, the matrix image shown in Figure 5 contains a grid image having multiple lines that intersect each other at multiple intersections (feature points). The matrix image may be composed of a checkerboard pattern image by filling in every other image in the grid.

[0070] In the example shown in Figure 5, the width of the one-dimensional code region 60 is the same as the width of the light-receiving IC chip 52 in the direction perpendicular to the Y direction. Therefore, the region of the reference image 58 corresponding to the light-receiving IC chip 52 is identified from one one-dimensional code region 60. However, the width of the one-dimensional code region 60 or the light-receiving IC chip 52 may be appropriately changed to, for example, identify the region of the reference image 58 corresponding to the light-receiving IC chip 52 from two one-dimensional code regions 60.

[0071] 5. Generation of correction parameters Figure 6 is a diagram illustrating the method for generating correction parameters. Note that Figure 6 also shows a portion of a predetermined area of ​​the reference image 58. When the correction reading image 54 is read by the image reading unit 30, the area of ​​the reference image 58 corresponding to the light-receiving IC chip 52 may tilt in the Y direction, as shown in Figure 6, due to positional displacement caused by the rotation of the light-receiving IC chip 52. Here, "tilting" specifically means that the pixels shift in the Y direction. For example, if a square image tilts in the Y direction, it becomes a parallelogram.

[0072] The correction parameters are generated by dividing the reference image 58 read by the image reading unit 30 into regions corresponding to the light-receiving IC chip 52, and calculating the tilt in the Y direction for each image. Since the correction parameters are generated appropriately for each region of the reference image 58 corresponding to the light-receiving IC chip 52, the correction parameters are associated with the light-receiving IC chip 52.

[0073] Correction parameters are generated using at least three intersections within the reference image 58. Figure 7, similar to Figure 6, illustrates the method for generating correction parameters. In the examples shown in Figures 6 and 7, correction parameters are generated using the first intersection P1, the second intersection P2, and the third intersection P3.

[0074] For example, as shown in Figure 7, if we assume that the parallelogram Q with angles at the first intersection P1, the second intersection P2, and the third intersection P3 is obtained by transforming the square R using an affine transformation, then the following equation (1) holds. In equation (1), the x and y coordinates with respect to the parallelogram Q are expressed as x' and y' in equation (1) below, and the x and y coordinates with respect to the square R are expressed as x and y in equation (1) below.

[0075]

number

[0076] Furthermore, A in equation (1) can be expressed by the following equation (2).

number

[0077] Furthermore, equation (1) can be transformed as shown in equation (3) below.

number

[0078] The right-hand side of equation (3) represents the transformation of parallelogram Q into square R.-1 Since this is a matrix for transforming parallelogram Q into square R, A -1 This corresponds to a correction parameter. A or A -1 This can be calculated using the above formula based on the coordinates of the first intersection P1, the second intersection P2, and the third intersection P3. As a result, A or A -1 From this, the angle θ corresponding to the tilt of the image can be calculated. Since the scale ratio and translation amount can also be calculated in the same way, the above equations (1) to (3) can be used for scaling the vertical and horizontal (X and Y directions) of an image, or for translational correction of multiple light-receiving IC chips 52 arranged in a staggered pattern as shown in Figure 11, which will be described later.

[0079] Thus, correction parameters can be calculated using the reference image 58, specifically the first intersection P1, second intersection P2, and third intersection P3 included in the reference image 58, but the method of calculation is not particularly limited. When calculating the correction parameters, other well-known techniques such as homography transformation may be considered.

[0080] However, the matrix image may include an image with multiple dots, in which case the feature points will be dots rather than intersections of lines. In other words, the types of feature points included in the matrix image are not limited. Furthermore, the correction parameters can be optimized using multiple feature points obtained from the reference image 58. In this case, well-known techniques such as the Levenberg-Marquardt method may be considered.

[0081] Figure 8 illustrates the method for correcting the image to be read 62. By acquiring correction parameters and storing them, for example, in the memory unit 26, the tilt of the image to be read 62 can be corrected as appropriate when the image to be read 62 is read, as shown in Figure 8. Specifically, the tilt of the image in the region of the image to be read 62 that is shifted in position due to rotation can be corrected using the correction parameters corresponding to the light-receiving IC chip 52.

[0082] However, the configuration may also correct for a shift along the Y-direction rather than the tilt of the image to be read 62. For example, if the placement positions of each light-receiving IC chip 52 are shifted in the Y-direction, as in the configuration shown in Figure 11 later, in which each light-receiving IC chip 52 is arranged in a staggered pattern, the shift of the image to be read 62 along the Y-direction can be corrected based on the correction parameters. Alternatively, the configuration may also correct the ratio of the dimensions of the image to be read 62 along the Y-direction to the dimensions along the X-direction based on the correction parameters.

[0083] 6. Functional configuration of the image reading device Figure 9 is a block diagram showing an example of the functional configuration of the image reading device 10 in this embodiment. Note that the RAM 24 and other components are omitted from the illustration in Figure 9.

[0084] The storage unit 26 stores correction parameter data 100. The correction parameter data 100 is data corresponding to the correction parameters. Note that multiple sets of correction parameter data 100 may be stored in the storage unit 26 as needed.

[0085] The control unit 20 functions as a parameter generation processing unit 102, a region identification processing unit 104, a parameter calculation processing unit 106, and a correction processing unit 108, etc., when the CPU 22 (see Figure 1) executes a control program. The parameter generation processing unit 102 includes the region identification processing unit 104 and the parameter calculation processing unit 106.

[0086] When the image reading unit 30 reads a correction reading image 54, which includes a code image 56 extending in a direction intersecting the transport direction and a reference image 58 aligned with the transport direction relative to the code image 56, the parameter generation processing unit 102 generates correction parameter data 100 based on the correction reading image 54.

[0087] The region identification processing unit 104 identifies the region in the reference image 58 that corresponds to each light-receiving IC chip 52 based on the code image 56.

[0088] The parameter calculation processing unit 106 calculates correction parameters corresponding to each light-receiving IC chip 52 based on the reference image 58 of the region corresponding to each light-receiving IC chip 52 identified by the region identification processing unit 104.

[0089] Specifically, the parameter calculation processing unit 106 calculates correction parameters corresponding to each light-receiving IC chip 52 based on at least three intersection points in the reference image 58.

[0090] When a read image 62 different from the correction read image 54 is read by the image reading unit as an image of the object T, the correction processing unit 108 corrects the read image 62 based on the correction parameter data 100.

[0091] In this embodiment, the case in which the object T is transported along the transport direction was used as an example for explanation, but instead of the object T being transported, the image reading unit 30 may move along the transport direction. In other words, it is acceptable as long as the image reading unit 30 and the object T move relative to each other along the transport direction.

[0092] Furthermore, although this embodiment describes a configuration in which only one image reading unit 30 is provided, multiple image reading units 30 may be used and arranged so that the main scanning direction of each image reading unit 30 extends in a different direction with respect to the reading direction.

[0093] Furthermore, in this embodiment, the light-receiving IC chip 52 may be arranged in advance as shown in Figures 10 and 11. Figure 10 is a schematic diagram showing another example of the configuration of the light-receiving unit 42 in this embodiment.

[0094] In the example shown in Figure 10, multiple light-receiving IC chips 52 are arranged in a line along the X direction, tilted with respect to the longitudinal direction of the image reading unit 30. In the example shown in Figure 10, the longitudinal direction of the light-receiving IC chips 52 does not coincide with the X direction, so the main scanning direction of the image reading unit 30 is different from the longitudinal direction.

[0095] Figure 11 is a schematic diagram showing yet another example of the configuration of the light-receiving unit 42 in this embodiment. In the example shown in Figure 11, a plurality of light-receiving IC chips 52 are arranged in a staggered pattern on two straight lines parallel to the X direction.

[0096] In the examples shown in Figures 10 and 11, the longitudinal directions of each light-receiving IC chip 52 are the same, and they are arranged in a line along the X direction. Therefore, it can be said that the multiple light-receiving IC chips 52 are arranged in the "line shape" described above.

[0097] As shown in the example in Figure 10, if each light-receiving IC chip 52 is tilted with respect to a direction perpendicular to the transport direction, the image of the object T read by each light-receiving IC chip 52 will be tilted. The correction parameters of this embodiment can also be used to correct such a tilted image of the object T.

[0098] Instead of arranging each light-receiving IC chip 52 as shown in Figures 10 and 11, it is also possible to have a configuration in which the image reading unit 30 has an elongated shape along the X direction (longitudinal direction), and multiple image reading units 30 are arranged in a line along the X direction. [Explanation of Symbols]

[0099] 10 Image reading device 30 Image reading unit 52 Light-receiving IC chip 54 Correction reading image 56 Code Images 58 Reference Image 62 Image to be read 100 Correction parameter data 102 Parameter generation processing unit 104 Area Identification Processing Unit 106 Parameter calculation processing unit 108 Correction Processing Unit T object

Claims

1. A correction pattern used in a line sensor that reads images of objects moving relatively along the transport direction using multiple image sensors arranged in a line, A correction pattern comprising a code image having multiple code regions associated with each image sensor and extending in a direction intersecting the transport direction, and a correction read image including a reference image aligned in the transport direction with respect to the code image.

2. The code image is composed of multiple lines extending in a direction intersecting the transport direction, arranged at intervals in the transport direction, wherein the thickness and spacing of the lines change along the direction intersecting the transport direction, as described in claim 1.

3. The correction pattern according to claim 1, wherein the code image is composed of a plurality of code regions having a width less than or equal to the width of each image sensor in a direction intersecting the transport direction, arranged in a direction intersecting the transport direction.

4. An image correction method using a correction pattern according to any one of claims 1 to 3, When the correction reading image is read by the line sensor as an image of the object, a parameter generation step is performed to generate correction parameters based on the correction reading image. An image correction method comprising a correction step of correcting the image to be read based on the correction parameters when the line sensor reads an image to be read that is different from the correction reading image.

5. An image processing apparatus that corrects the image to be read using the image correction method described in claim 4.

6. A line sensor reads images of objects moving relatively along the transport direction using multiple image sensors arranged in a line, A parameter generation processing unit generates correction parameters based on the correction read image when the correction read image included in a correction pattern, which comprises a code image extending in a direction intersecting the transport direction and a reference image aligned with the transport direction relative to the code image, is read by the line sensor as an image of the object. The system includes a correction processing unit that corrects the image to be read based on the correction parameters when the line sensor reads an image of the object that is different from the correction reading image. The parameter generation processing unit, A region identification processing unit that identifies regions corresponding to each image sensor in the reference image based on the code image, An image reading device including a parameter calculation processing unit that calculates the correction parameters corresponding to each image sensor based on the reference image of the region corresponding to each image sensor identified by the region identification processing unit.

7. The image reading device according to claim 6, wherein the reference image includes a matrix image.

8. The image reading device according to claim 7, wherein the matrix image includes a grid-like image having a plurality of intersecting lines.

9. The image reading device according to claim 7, wherein the matrix image includes an image in which a plurality of dots are arranged.

10. The image reading device according to claim 9, wherein the parameter calculation processing unit calculates the correction parameters corresponding to each image sensor based on at least three feature points in the reference image.

11. The image reading device according to claim 10, wherein the at least three feature points include a first feature point, a second feature point, and a third feature point that is not on the straight line connecting the first and second feature points.

12. The image reading device according to claim 6, comprising a plurality of line sensors, wherein the main scanning direction of each line sensor extends in a direction different from the transport direction.

13. The image reading device according to claim 6, wherein the line sensor has an elongated shape along a longitudinal direction intersecting the transport direction, and the plurality of image sensors, which are inclined with respect to the longitudinal direction, are arranged in a line along the longitudinal direction.

14. The image reading device according to claim 6, wherein the line sensors have an elongated shape along a longitudinal direction intersecting the transport direction, and a plurality of them are arranged in a line along the longitudinal direction.

15. The image reading device according to claim 6, wherein the correction processing unit corrects the tilt of the image to be read based on the correction parameter.

16. The image reading device according to claim 6, wherein the correction processing unit corrects the deviation of the image to be read along the transport direction based on the correction parameters.

17. The image reading device according to claim 6, wherein the correction processing unit corrects the ratio of the dimension of the image to be read along the transport direction to the dimension along the direction intersecting the transport direction based on the correction parameter.

18. A correction pattern used in a line sensor that reads images of objects moving relatively along the transport direction using a plurality of image sensors arranged in a line, the following: The system includes a code image extending in a direction intersecting the transport direction, and a correction reading image including a reference image aligned with the transport direction relative to the code image. The code image is a correction pattern, comprising a plurality of code regions having a width less than or equal to the width of each image sensor along a direction intersecting the transport direction, arranged along a direction intersecting the transport direction.

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