JP2015052886A - Printed matter inspection device and printed matter inspection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform an inspection specialized for a character part of a printed matter, and automatically adjust a parameter of a printing process for returning to a normal state if there is any abnormality.SOLUTION: An inspection image acquisition section 213 reads a printing paper (printed matter) and acquires inspection image data. A master image generation section 211 generates master image data from source data of the printed matter. An inspection control section 214 extracts character areas of the master image data and the inspection image data, generates difference data between them (difference image data), inspects an abnormal state (character thickening, character thinning or the like) of characters in the printed matter on the basis of the difference data, transmits control information to a printing device 101 according to the abnormal state, and adjusts a parameter of a printing process.

Description

  The present invention relates to a printed matter inspection apparatus and a printed matter inspection method for inspecting the print quality of a printed matter.

  2. Description of the Related Art Conventionally, as a post-printing process, a printed material inspection device that reads a printing paper (printed material) output from a printing device with a camera, a line sensor, or the like and inspects whether printing is performed normally is known. In such a printed matter inspection apparatus, an inspection image generally obtained by reading a printed matter is compared with a master image generated from the original data of the printed matter, and it is determined whether or not the printed matter is normal based on the degree of the difference.

  By the way, the character portion of the inspection image often uses a technique of making the character edge darker than the character by image processing to increase the sharpness of the character. As a result, particularly small point characters may become fat or crushed due to fixing or the like and become unreadable. Further, in the process of printing (charging / exposure / development / transfer / fixing), the thickness of the target character may be smaller than that of the target character. In such a case, it is necessary to adjust the thickness of the character by adjusting the parameters of the printing process.

  However, in the conventional printed matter inspection apparatus, a method of comparing the inspection image with the master image and stopping printing when it is determined as abnormal is common (for example, Patent Document 1). For this reason, in the case of mass printing in units of 10,000 copies, etc., a person is constantly monitoring beside the printing press. If there is an abnormality, the cause is analyzed and the character is abnormal each time. There was a need to manually adjust the parameters of the printing process.

  SUMMARY OF THE INVENTION An object of the present invention is to make it possible to automatically adjust parameters of a printing process when a character portion of a printed material is inspected in a printed material inspection apparatus for inspecting the print quality of the printed material and there is an abnormality.

  The present invention is a printed matter inspection apparatus for inspecting a printed matter printed by a printing apparatus, and generates inspection image acquisition means for reading the printed matter and obtaining it as inspection image data, and generating master image data from the original data of the printed matter A master image generating means for generating, a character area extracting means for extracting the character area of the master image data and the inspection image data, generating difference data of the character area of the master image data and the inspection image data, and the difference data And an adjustment unit that adjusts a parameter of a printing process of the printing apparatus according to the abnormal state of the character of the printed matter. .

  According to the present invention, it is possible to perform inspection specially for the character portion of a printed matter, and automatically return to normal if there is an abnormality.

It is a schematic block diagram of the printing system which comprises a printed matter inspection apparatus (inspection apparatus). It is a block diagram concerning one embodiment of a processing system of a printing device and an inspection device. It is a detailed block diagram of a master image generation part. It is a detailed block diagram of an image forming unit. It is a figure explaining exposure of a character part. It is a figure which shows the relationship between the exposure position of Example 1, and exposure intensity. FIG. 3 is a diagram illustrating a specific processing image of the first embodiment. It is a flowchart explaining operation | movement of Example 1 of a test | inspection control part. It is a detailed flowchart of character area extraction. It is a figure which shows the processing image of character area extraction. It is a figure which shows a correction table. It is a flowchart explaining operation | movement of Example 2 of a test | inspection control part. It is a figure which shows the relationship between the exposure position of Example 3, and exposure intensity. It is a flowchart explaining operation | movement of Example 3 of a test | inspection control part. It is a flowchart explaining operation | movement of Example 4 of a test | inspection control part. It is a flowchart explaining operation | movement of Example 5 of a test | inspection control part. It is a detailed flowchart of a small letter area | region determination. It is a figure which shows the process image of a small letter area | region determination.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of a printing system including a printed matter inspection apparatus according to an embodiment of the present invention. In FIG. 1, reference numeral 101 denotes a printing apparatus, and 102 denotes an operation unit of the printing apparatus 101. Reference numeral 103 denotes a printed matter inspection apparatus (hereinafter simply referred to as an inspection apparatus) connected to the printing apparatus 101, and reference numeral 104 denotes a paper discharge apparatus connected to the inspection apparatus 103.

  The printing apparatus 101 receives print data from a host apparatus (not shown) such as a DFE (Digital Front End) server and performs necessary image processing. The printing apparatus 101 forms electrostatic latent images of K (black), C (cyan), M (magenta), and Y (yellow) on the photosensitive drums 113, 114, 115, and 116, respectively, and further a toner image. And the toner image is transferred onto the intermediate transfer belt 111 in an overlapping manner. In parallel with this, the printing apparatus 101 feeds the sheet from the sheet feeding unit 118, transfers the YMCK toner image on the intermediate transfer belt 111 to the sheet by the transfer roller 112, and fixes it by the fixing roller 117. To do. In the case of single-sided printing, the printing apparatus 101 conveys the fixed printing paper to the inspection apparatus 103 as it is, but in the case of double-sided printing, the printing paper is reversed and the same applies to the other side of the printing paper. After the processing, the sample is conveyed to the inspection apparatus 103.

  The inspection apparatus 103 reads the printing paper (printed material) conveyed from the printing apparatus 101 by the reading units 131 and 132 and acquires inspection image data. Specifically, when the printing paper is single-sided printing, the reading unit 131 reads one side (front surface) of the printing paper, and when the printing paper is double-sided printing, the reading units 131 and 132 read both sides of the printing paper ( Read the front and back surfaces. The inspection apparatus 103 inspects the abnormal state of the characters on the printing paper (printed material) based on the acquired inspection image data, and automatically adjusts the parameters of the printing process of the printing apparatus 101 according to the abnormal state. As a result, after that, the printing apparatus 101 outputs a high-quality printed matter in which the character abnormality is eliminated. This will be described later.

  The printing paper (printed matter) that has passed through the reading units 131 and 132 of the inspection device 103 is conveyed to the paper discharge device 104 as it is. The paper discharge device 104 stacks the printing paper conveyed from the inspection device 103 on the paper discharge tray 141.

  FIG. 2 is a block diagram according to an embodiment of a processing system of the printing apparatus 101 and the inspection apparatus 103.

  In the printing apparatus 101, a RIP (Raster Image Processor) 201 receives print data such as PDL such as Post Script and TIFF from a higher-level apparatus (not shown), and generates CMYK RIP image data (bitmap data). A print control unit 202 controls the overall operation of the printing apparatus 101. The print control unit 202 sends the CMYK RIP image data generated by the RIP 201 to the print image processing unit 203 and the inspection apparatus 103. The print image processing unit 203 receives CMYK RIP image data from the print control unit 202, performs necessary image processing, and generates write data (print image data) such as a laser. In the print image processing unit 203, for example, a digital filter is used to make the character edge darker than that in the character to increase the sharpness of the character. The image forming unit 204 performs a printing process (charging / exposure / development / transfer / fixing) based on the print image data generated by the print image processing unit 203 and outputs a printing sheet (printed material). As shown in FIG. 1, the image forming unit 204 is realized by a general electrophotographic image forming mechanism.

  In the inspection apparatus 103, a master image generation unit (master image generation unit) 211 generates master image data from CMYK RIP image data (original data of a printed matter) sent from the printing apparatus 101. As will be described later, the master image data has the same format as the inspection image data of the inspection image acquisition unit 213. The buffer memory 212 holds master image data generated by the master image generation unit 211. The inspection image acquisition unit (inspection image acquisition means) 213 reads the printing paper (printed material) output from the printing apparatus 101 and acquires it as inspection image data. The inspection image acquisition unit 213 corresponds to the reading units 131 and 132 in FIG. 1 and is configured by a CMOS sensor or the like. The inspection control unit 214 receives the master image data from the buffer memory 212 and the inspection image data from the inspection image acquisition unit 213, and extracts the inspection image data and the character area of the master image data (character area extraction unit). Generate difference data of the character area of the image data and the master image data, inspect the abnormal state of the character of the printed matter based on the difference data (inspection means), print according to the abnormal state of the character of the printed matter Control information is sent to the print control unit 202 and print image processing unit 203 of the apparatus 101 to automatically adjust the parameters of the printing process (adjustment unit).

  In the embodiment, it is assumed that the inspection control unit 214 includes a CPU, a ROM, a RAM, and the like. The ROM stores programs, tables, and other necessary information in advance. The CPU executes the program stored in the ROM and refers to a table, information, or the like as necessary, thereby realizing the functions of each processing means (character area extraction means, inspection means, adjustment means). The RAM stores data being processed by the CPU. A part of the RAM may be used as the buffer memory 212.

  FIG. 3 is a block diagram according to an embodiment of the master image generation unit 211 in the inspection apparatus 103. The master image generation unit 211 includes a small-value multi-value conversion processing unit 301, a resolution conversion processing unit 302, and a color conversion processing unit 303.

  The low-value multi-value conversion processing unit 301 multi-values CMYK RIP image data sent from the print control unit 202 of the printing apparatus 101. The CMYK RIP image data generated by the RIP 201 is generally binary image data. The image forming unit 204 executes image forming processing based on the binary image data of each color of CMYK. On the other hand, the inspection image data acquired by the inspection image acquisition unit 213 of the inspection apparatus 103 is multi-value image data of each color of RGB. For this reason, the low-value / multi-value conversion processing unit 301 first converts binary RIP image data of each color of CMYK into multi-value image data. Multi-value image data is represented by, for example, 8 bits for each CMYK.

  The resolution conversion processing unit 302 performs resolution conversion so that the resolution of each CMYK multilevel image data matches the resolution of the inspection image data. For example, when the inspection image data is 200 dpi, the resolution of each CMYK multivalued image data is converted to 200 dpi.

  The color conversion processing unit 303 performs color conversion on the CMYK multivalued image data subjected to the resolution conversion by the resolution conversion processing unit 302 to the same RGB format image data as the inspection image data.

  Thereby, master image data having the same format as the inspection image data is generated. For example, both the master image data and the inspection image data are represented by 8 bits of RGB for each pixel with a resolution of 200 dpi. The pixel values are 0 for true black and 255 for true white.

  FIG. 4 is a detailed block diagram of the image forming unit (print engine) 204 of the printing apparatus 101. The image forming unit 204 includes a charging unit 401, an exposure unit 402, a developing unit 403, a transfer unit 404, and a fixing unit 405, and performs image forming processing based on print image data from the print image processing unit 203, and print paper ( Print).

  The inspection control unit 214 of the inspection apparatus 103 performs an inspection specialized for characters on the printing paper (printed material), and when it is determined that the characters of the printed material are abnormal (character thickening, character thinning, etc.), the printing control unit of the printing apparatus 101 Control information is sent to 202 and the print image processing unit 203 to adjust the parameters of the printing process, and control is performed so that characters of the printed matter become normal.

  Hereinafter, some specific examples of the operation of the inspection control unit 214 of the inspection apparatus 103 will be described in detail.

  In the first embodiment, the character edge exposure intensity is made weaker than the exposure intensity in the character when the abnormal character of the printed matter is thick, and the character edge exposure intensity is set to the exposure in the character when the character is thin. By making it stronger than strength, the thickness and thinness of characters are automatically adjusted.

  FIG. 5 is a diagram for explaining exposure of a character portion. In FIG. 5, reference numeral 501 denotes a photosensitive drum (corresponding to 113 to 116 in FIG. 1), and 502 denotes a light source such as a laser light source.

  After the outer peripheral surface of the photoconductive drum 501 is uniformly charged, the outer peripheral surface of the photoconductive drum 501 is exposed according to the print image data by light (laser light or the like) from the light source 502 and electrostatic latent An image is formed. Here, a character portion (shaded portion) is divided into a character edge and a character, exposure of the character edge is exposure 1 and exposure 3, and exposure in the character is exposure 3.

  FIG. 6 is a graph showing the exposure position and exposure intensity in this example. FIG. 6A shows the case where the character thickness of the printed material is larger than the allowable value (character thickening). In this case, the exposure intensity (exposure 1, exposure 3) of the character edge is set to the exposure intensity ( Weaker than exposure 2). FIG. 6B shows a case where the character thickness of the printed material becomes thinner than the allowable value (character thinning). In this case, the exposure intensity (exposure 1, exposure 3) of the character edge is represented by the exposure intensity ( Make it stronger than exposure 2). As a result, the thickness of the character can be automatically returned to the normal state.

  FIG. 7 is a diagram showing a specific processing image of the present embodiment. In FIG. 7, the horizontal axis represents the number of printed sheets (how many sheets are printed), and the vertical axis represents the character thickness of the inspection image that is a printed matter. In this example, since the third and sixth sheets are thicker than the allowable range, the process of thinning the characters is performed. That is, the exposure intensity at the character edge is made lower than the exposure intensity in the character. Further, since the seventh sheet is thinner than the allowable range, processing for thickening characters is performed. That is, the exposure intensity at the character edge is made stronger than the exposure intensity in the character. Similarly, when the character thickness of the inspection image becomes thicker than the allowable range, the character is thinned. When the character thickness is thinned beyond the allowable range, the character is thickened.

  FIG. 8 is a flowchart for explaining the operation of this embodiment in the inspection control unit 214 of the inspection apparatus 103.

  The inspection control unit 214 takes in the master image data from the buffer memory 212 (step 1001), and takes in the inspection image data of the printed matter from the inspection image acquisition unit 213 (step 1002). As described above, the master image data and the inspection image data are image data of the same format. For example, both have a resolution of 200 dpi and are represented by 8 bits for each color of RGB for each pixel. The pixel values are 0 for true black and 255 for true white.

  The inspection control unit 214 extracts a character area from the master image data (step 1003). FIG. 9 shows a process flowchart of character area extraction, and FIG. 10 shows a process image of character area extraction. FIG. 10A shows an original image of master image data.

  In the character area extraction process, first, connected pixels such as black pixels are extracted from the master image data, and a rectangle (connected rectangle) including the connected pixels is generated (step 2001). FIG. 10B shows this. Next, a rectangle including adjacent connected rectangles is generated as a character rectangle (step 2002). FIG. 10C shows this. Finally, a rectangle including the adjacent character rectangle is generated and set as a character area (step 2003). FIG. 10D shows this.

  Note that the character area extraction method is not limited to the above-described method using connected pixels, and any method may be used as long as the character area can be extracted.

  Returning to FIG. 8, the inspection control unit 214 next extracts a character region from the inspection image data (step 1004). Specifically, using the character area of the master image data, an area corresponding to the character area of the master image data is extracted from the inspection image data, and is used as the character area of the inspection image data.

Next, the inspection control unit 214 generates difference data (difference image data) between the character areas of the master image data and the inspection image data (step 1005). Specifically, with respect to the character regions of the master image data and the inspection image data, for each pixel at the same position, a difference (difference value) between both pixel values is calculated to generate difference data (difference image data). Here, the difference value is obtained by the following equation.
Difference value = pixel value of inspection image-pixel value of master image

  Next, the inspection control unit 214 inspects whether or not the printed material is thickened based on the difference data (difference image data) between the character areas of the master image data and the inspection image data (step 1006). Specifically, in the difference data, the number of pixels having a negative difference value equal to or less than a predetermined negative threshold (th1) is calculated, and the ratio of the number of pixels to the number of pixels in the entire difference data (character thickness) It is checked whether α is equal to or greater than a predetermined threshold value (th2). If α is greater than or equal to th2, it is determined that the character is fat. In this case, the inspection control unit 214 sends control information for making the exposure intensity of the character edge of the character part weaker than the exposure intensity in the character to the print image processing unit 203 (step 1007). As part of this control information, a character edge correction amount corresponding to the character thickness degree α is sent to the print image processing unit 203. The print image processing unit 203 changes the parameter value of the filter (digital filter) in accordance with the correction amount so that the sharpness of the character edge of the print image data is lowered. As a result, the exposure unit 402 controls the exposure intensity of the character edge of the character part to be lower than the exposure intensity of the character.

  When the character weight is within the allowable value (α <th2), the inspection control unit 214 then reduces the character of the printed matter based on the difference data (difference image data) between the character areas of the master image data and the inspection image data. Existence is checked (step 1008). Specifically, in the difference data, the number of pixels having a positive difference value equal to or greater than a predetermined positive threshold (th3) is calculated, and the ratio of the number of pixels to the number of pixels in the entire difference data (character fineness) It is checked whether or not β is equal to or greater than a predetermined threshold value (th4). If β is greater than or equal to th4, it is determined that the character is thin. In this case, the inspection control unit 214 sends control information for making the exposure intensity of the character edge of the character part stronger than the exposure intensity in the character to the print image processing unit 203 (step 1009). As part of this control information, a character edge correction amount corresponding to the character fineness degree β is sent to the print image processing unit 203. The print image processing unit 203 changes the parameter value of the filter according to the correction amount so that the sharpness of the character edge of the print image data is increased. As a result, the exposure unit 402 controls the exposure intensity of the character edge of the character part to be higher than the exposure intensity of the character.

  On the other hand, when the character thinning is within the allowable value (β <th4), the inspection control unit 214 determines that the character of the printed matter is normal. Note that the presence or absence of character thinning may be inspected first, and if the character thinness is within an allowable value, the presence or absence of character thickening may be inspected next. If the printed material is normal, the inspection control unit 214 does nothing.

  Hereinafter, the inspection control unit 214 repeats the process of FIG. 8 for each printing paper (printed material).

  FIG. 11 is a diagram illustrating an example in which the character edge correction amount corresponding to the character thickness degree α and the character thinness degree β is acquired using a lookup table (LUT). In FIG. 11, correction table (1) 1101 and correction table (2) 1102 are LUTs, and these are stored in advance in a nonvolatile memory.

  When the inspection control unit 214 determines that the printed matter is abnormally thick (α ≧ th2), the inspection control unit 214 reads the character edge correction amount A from the correction table (1) 1101 using the character thickness degree α, and the print image processing unit 203 The exposure intensity at the character edge of the character portion is controlled to be lower than the exposure intensity in the character. If it is determined that the printed material is abnormally thin (β ≧ th4), the character edge correction amount B is read from the correction table (2) 1102 using the character fineness degree β and sent to the print image processing unit 203. Thus, the exposure intensity of the character edge of the character part is controlled to be higher than the exposure intensity in the character.

  The character edge correction amount corresponding to the character thickness degree α and the character thinness degree β may be directly calculated using a correction conversion formula.

  In the first embodiment, when the printed matter is abnormally thick or thin, the exposure intensity is differentiated between the character edge and the character. However, in the second embodiment, the entire character area is detected when the thick character is abnormal. In the case of an abnormal character thinning, the thickness and thinness of the character are automatically adjusted by increasing the exposure intensity of the entire character area.

  FIG. 12 is a flowchart for explaining the operation of this embodiment in the inspection control unit 214 of the inspection apparatus 103. In FIG. 12, the operations in steps 1001 to 1008 are the same as those in FIG.

  When the printed matter is abnormally thick (α ≧ th2), the inspection control unit 214 controls the print image processing unit 203 to make the overall exposure intensity of the character area weaker than the exposure intensity of other areas. (Step 3001). The control information includes a correction amount corresponding to the character thickness degree α. If the printed material is abnormal in character thinning, control information for making the exposure intensity of the entire character area higher than the exposure intensity of other areas is sent to the print image processing unit 203 (step 3002). The control information includes a correction amount corresponding to the character fineness degree β.

  The print image processing unit 203 adjusts the gradation of the character part of the print image data, for example, according to the correction amount sent from the inspection control unit 214. As a result, the exposure unit 402 controls the exposure intensity of the character part to be weaker or stronger than other areas.

  Also in the present embodiment, the correction amount corresponding to the character thickness degree α and the character thinness degree β can be acquired using the LUT.

  In the third embodiment, the character edge exposure time is set shorter than the exposure time in the character when the character abnormality of the printed matter is thick, and the character edge exposure time is set in the character thin case. By making it longer than the exposure time, the thickness and thinness of characters are automatically adjusted.

  FIG. 13 is a graph showing the exposure position and exposure time in this example. Here, exposure 1 and exposure 3 indicate character edge exposure, and exposure 3 indicates character exposure (see FIG. 5). FIG. 13A shows a case where the abnormality of the character of the printed matter is character thickening. In this case, the exposure time of the character edge (exposure 1, exposure 3) is made shorter than the exposure time in the character (exposure 2). FIG. 13B shows a case where the abnormality of the printed matter is a thin character. In this case, the exposure time (exposure 1, exposure 3) of the character edge is made longer than the exposure time in the character (exposure 2). As a result, the thickness of the character can be automatically returned to the normal state.

  FIG. 14 is a flowchart for explaining the operation of this embodiment in the inspection control unit 214 of the inspection apparatus 103. In FIG. 14, the operations in steps 1001 to 1008 are the same as those in FIG.

  When the printed matter is abnormally thick (α ≧ th2), the inspection control unit 214 controls the print image processing unit 203 to make the exposure time of the character edge of the character part shorter than the exposure time in the character. (Step 4001). The control information includes a character edge correction amount corresponding to the character thickness degree α. In addition, when the printed material has an abnormal character thinning (β ≧ th4), the inspection control unit 214 makes the exposure time of the character edge of the character part shorter than the exposure time in the character with respect to the print image processing unit 203. Control information is sent (step 4002). The control information includes a character edge correction amount corresponding to the character fineness degree β.

  The print image processing unit 203 adjusts the length of the character edge of the print image data according to the character edge correction amount sent from the inspection control unit 214. As a result, when the character of the printed matter is thick, the exposure unit 402 controls the exposure time of the character edge to be shorter than the exposure time in the character, and the character abnormality is thin. The exposure time for the character edge is controlled to be longer than the exposure time for the character.

  Also in this embodiment, the correction amount (character edge correction amount) corresponding to the character thickness degree α and the character thinness degree β can be obtained using the LUT.

  In the third embodiment, when the printed matter is abnormally thick or thin, the exposure time differs between the character edge and the character. However, in the fourth embodiment, the entire character area is exposed when the thick character is abnormal. The time is shorter than the exposure time of other areas, and in the case of character thinning abnormality, the exposure time of the entire character area is set longer than the exposure time of other areas, and the thickness and thinness of characters are automatically adjusted. It is.

  FIG. 15 is a flowchart for explaining the operation of this embodiment in the inspection control unit 214 of the inspection apparatus 103. In FIG. 15, the operations in steps 1001 to 1008 are the same as those in FIG.

  When the printed matter is abnormally thick (α ≧ th2), the inspection control unit 214 sends control information for making the exposure time of the character area shorter than the exposure time of other areas to the print image processing unit 203. (Step 5001). The control information includes a correction amount corresponding to the character thickness degree α. If the printed material is abnormal in character thinness, control information for making the exposure time of the character area longer than the exposure time of other areas is sent to the print image processing unit 203 (step 5002). The control information includes a correction amount corresponding to the character fineness degree β.

  The print image processing unit 203 adjusts the length of the character part of the print image data according to the correction amount sent from the inspection control unit 214. As a result, the exposure unit 402 controls the exposure time of the character region to be shorter or longer than the other regions.

  Also in the present embodiment, the correction amount corresponding to the character thickness degree α and the character thinness degree β can be acquired using the LUT.

  In particular, in the case of lowercase letters, if the characters become fat or thin, they become unreadable. Example 5 specializes the inspection object to lowercase letters in the printed matter. When the lowercase character area is abnormal in character thickening, the exposure intensity of the character edge is made weaker than the exposure intensity in the character, and in the case of abnormal character thinning, The exposure intensity at the character edge is made stronger than the exposure intensity in the character, and the lowercase letters are automatically adjusted to an appropriate thickness.

  FIG. 16 is a flowchart for explaining the operation of the present embodiment in the inspection control unit 214 of the inspection apparatus 103.

  The inspection control unit 214 takes in the master image data from the buffer memory 212 (step 6001), and takes in the inspection image data of the printed matter from the inspection image acquisition unit 213 (step 6002). The master image data and the inspection image data are image data in the same format. For example, both have a resolution of 200 dpi and are represented by 8 bits for each color of RGB for each pixel. The pixel values are 0 for true black and 255 for true white.

  Next, the inspection control unit 214 extracts a character area from the master image data (step 6003). As described with reference to FIGS. 9 and 10, in the character region extraction process, first, connected pixels such as black pixels are extracted from the master image data, and a rectangle (connected rectangle) including the connected pixels is generated. Next, a rectangle including adjacent connected rectangles is generated as a character rectangle. Finally, a rectangle including the adjacent character rectangle is generated and set as a character area.

  Next, the inspection control unit 214 determines whether or not the character area is a lowercase area (step 6004). FIG. 17 shows a detailed flowchart of lowercase area determination, and FIG. 18 shows a processing image of lowercase area determination. FIG. 18A shows the extracted character area.

The inspection control unit 214 first calculates the sum sumh of the number of pixels in the vertical direction of each character rectangle in the extracted character region (step 7001). In the example of FIG. 18B, sumh = h1 + h2 + h3. Next, the sum sumw of the number of pixels in the horizontal direction of each character rectangle included in the extracted character area is calculated (step 7002). In the example of FIG. 18B, sumw = w1 + w2 + w3. Next, the length of the character rectangle per character (average character rectangle length) ave_d is calculated (step 7003). Assuming that the number of characters in the character area is n and the image resolution is m (dpi), ave_d (inch) is obtained by the following equation.
ave_d = {(sumh + sumw) / (n × 2)} / m)

  The inspection control unit 214 determines whether or not the average character rectangle length ave_d is smaller than a threshold value (lowercase threshold value) smoji_d (step 7004). If ave_d <smoji_d, the character area is determined to be a lowercase area (step 7005), and if ave_d ≧ smoji_d, it is determined that the character area is not a lowercase area.

  Returning to FIG. 16, the inspection control unit 214 ends the process when the character area is not the lower case area, and performs the processing after step 6005 only when the character area is the lower case area. If there are a plurality of character areas, and there is at least one lowercase area, the processing from step 6005 is performed.

  If the character area of the master image data is a lower case area, the inspection control unit 214 next extracts the character area (lower case area) from the inspection image data (step 6005). Specifically, using the character area (lowercase area) of the master image data, the area corresponding to the character area of the master image data is extracted from the inspection image data, and the character area (lowercase area) of the inspection image data is extracted. To do.

Next, the inspection control unit 214 generates difference data (difference image data) between the character area (lower case area) between the master image data and the inspection image data (step 6006). Specifically, for the character area (lower-case area) of the master image data and the inspection image data, the difference (difference value) between the two pixel values is calculated for each pixel at the same position as in the first embodiment. To generate difference data (difference image data). Here, the difference value is obtained by the following equation.
Difference value = pixel value of inspection image-pixel value of master image

  Next, the inspection control unit 214 inspects whether or not the printed material is thickened based on the difference data (difference image data) between the master image data and the character area (lowercase area) of the inspection image data (step 6007). Specifically, in the difference data, the number of pixels having a negative difference value equal to or less than a predetermined negative threshold (th5) is calculated, and the ratio of the number of pixels to the number of pixels in the entire difference data (character thickness) It is checked whether α is equal to or greater than a predetermined threshold value (th6). If α is greater than or equal to th6, it is determined that the character is fat. In this case, the inspection control unit 214 sends control information for making the exposure intensity of the character edge of the character part (lower case) lower than the exposure intensity in the character to the print image processing unit 203 (step 6008). As part of this control information, a character edge correction amount corresponding to the character thickness degree α is sent to the print image processing unit 203. The print image processing unit 203 changes the parameter value of the filter (digital filter) in accordance with the correction amount so that the sharpness of the character edge of the print image data is lowered. As a result, the exposure unit 402 controls the exposure intensity of lowercase character edges to be lower than the exposure intensity in characters.

  If the character weight is within the allowable value (α <th6), the inspection control unit 214 then prints the printed material based on the difference data (difference image data) between the character area (lower case area) between the master image data and the inspection image data. In step 6009, it is checked whether there is any character thinning. Specifically, in the difference data, the number of pixels having a positive difference value equal to or greater than a predetermined positive threshold (th7) is calculated, and the ratio of the number of pixels to the number of pixels in the entire difference data (character fineness) It is checked whether β is equal to or greater than a predetermined threshold (th8). If β is greater than or equal to th8, it is determined that the character is thin. In this case, the inspection control unit 214 sends control information for making the exposure intensity of the character edge of the character part (lower case) stronger than the exposure intensity in the character to the print image processing unit 203 (step 6010). As part of this control information, a character edge correction amount corresponding to the character fineness degree β is sent to the print image processing unit 203. The print image processing unit 203 changes the parameter value of the filter according to the correction amount so that the sharpness of the character edge of the print image data is increased. As a result, the exposure unit 402 is controlled so that the exposure intensity of lowercase character edges is higher than the exposure intensity in characters.

On the other hand, when the character thinness is within the allowable value (β <th8), the inspection control unit 214 determines that the character (lower case) of the printed matter is normal. Note that the presence or absence of character thinning may be inspected first, and if the character thinness is within an allowable value, the presence or absence of character thickening may be inspected next. When the characters (lower case) of the printed material are normal, the inspection control unit 214 does nothing.
Hereinafter, the inspection control unit 214 repeats the process of FIG. 16 for each printing paper (printed material).

  In the sixth embodiment, the inspection target is specified as the lower case area of the printed matter, and when the character thickness is abnormal, the exposure intensity of the entire character area (lower case area) is reduced, and when the character thin state is abnormal, the character area ( Lower case area) By increasing the overall exposure intensity, the upper and lower case letters are prevented from becoming thick and thin.

  Since the operation of the sixth embodiment is basically the same as that of the second embodiment except that the target character area is a lower-case area, a description thereof will be omitted.

  In the seventh embodiment, the inspection target is specified in the lower case area of the printed matter, and when the character is thick, the exposure time of the character edge is shorter than the exposure time in the character. When the character is thin, the character is By making the exposure time of the edge longer than the exposure time in the character, it is possible to suppress thickening and thinning of lowercase letters.

  Since the operation of the seventh embodiment is basically the same as that of the third embodiment except that the target character area is a lowercase area, a description thereof will be omitted.

  In the eighth embodiment, the inspection target is specified in the lower case area of the printed matter, and when the character thickness is abnormal, the exposure time of the entire character area (lower case area) is shortened. (Area) By increasing the exposure time of the entire area, it is possible to prevent the lowercase letters from becoming thicker or thinner.

  Since the operation of the eighth embodiment is basically the same as that of the fourth embodiment except that the target character area is a lower-case area, a description thereof will be omitted.

  Although several embodiments have been described in detail above, the present invention is not limited to these embodiments. In the first to eighth embodiments, the inspection control unit 214 of the inspection apparatus 103 sends control information (such as a correction amount) to the print image processing unit 203 of the printing apparatus 101, and the print image processing unit 203 performs predetermined image processing. The exposure unit 402 automatically controls the exposure intensity and exposure time, but sends control information from the inspection control unit 214 to the exposure unit 402, and controls the exposure intensity and exposure time on the exposure unit 402 side. You may do it.

  Also, the inspection control unit 214 of the inspection apparatus 103 sends control information to the print control unit 202 of the printing apparatus 101, and the print control unit 202 controls the operation of the developing unit 403, thereby adjusting character weight and thinness. It may be. For example, the background potential in the developing unit 403 is controlled (when the character is thick, the background potential is increased, and when the character is thin, the background potential is decreased), or the linear velocity ratio in the developing unit 403 is controlled (the character is If it is thick, the line speed ratio is increased, and if the character is thin, the line speed ratio is decreased.) The toner pumping amount in the developing unit 403 is controlled (if the character is thick, the pumping amount is decreased, and the character is thin. Increase the pumping amount).

  In addition, in the generation of the difference data of the character area of the master image data and the inspection image data, the color image is not particularly considered. However, when the color image is considered, for example, if the difference data is generated as follows, Good. In the first method, difference data is generated by calculating a difference between the G component of the inspection image data and the G component of the master image data. In the second method, the GRB images of the inspection image data and the master image data are L * a * b converted, and the difference data is generated by calculating the difference for the L * component (luminance component).

101 Printing Device 103 Inspection Device (Printed Material Inspection Device)
201 RIP
202 Print Control Unit 203 Print Image Processing Unit 204 Image Forming Unit (Print Engine)
211 Master Image Generation Unit 212 Buffer Memory 213 Inspection Image Acquisition Unit 214 Inspection Control Unit 401 Charging Unit 402 Exposure Unit 403 Development Unit 404 Transfer Unit 405 Fixing Unit

JP 2012-108854 A

Claims (8)

A printed matter inspection device for inspecting a printed matter printed by a printing device,
Inspection image acquisition means for reading the printed matter and acquiring it as inspection image data;
Master image generation means for generating master image data from the original data of the printed matter;
A character area extracting means for extracting a character area of the master image data and the inspection image data;
Generating the difference data of the character area of the master image data and the inspection image data, and inspecting the abnormal state of the characters of the printed matter based on the difference data;
Adjusting means for adjusting parameters of a printing process of the printing apparatus according to an abnormal state of characters of the printed matter;
A printed matter inspection apparatus comprising: The character area extraction unit extracts a character area of the master image data, extracts an area corresponding to the character area of the master image data from the inspection image data, and sets it as a character area of the inspection image data.
The printed matter inspection apparatus according to claim 1. The inspection means inspects character thickening and character thinning of the printed matter based on the difference data,
In the case where the character is thick, the adjustment means weakens the exposure intensity of the character area compared to other areas, and in the case of the thin character, the adjustment means increases the exposure intensity of the character area compared to other areas. ,
The printed matter inspection apparatus according to claim 1, wherein: The inspection means inspects character thickening and character thinning of the printed matter based on the difference data,
The adjusting means reduces the exposure intensity of the character edge in the character area compared to the exposure intensity in the character when the character is thick, and reduces the exposure intensity of the character edge of the character area when the character is thin. Make it stronger than the exposure intensity in the text,
The printed matter inspection apparatus according to claim 1, wherein: The inspection means inspects character thickening and character thinning of the printed matter based on the difference data,
The adjusting means shortens the exposure time of the character area in comparison with the other areas when the character is thick, and increases the exposure time of the character area as compared with the other areas in the case of thinning the character. ,
The printed matter inspection apparatus according to claim 1, wherein: The inspection means inspects character thickening and character thinning of the printed matter based on the difference data,
The adjusting means shortens the exposure time of the character edge in the character area compared to the exposure time in the character when the character is thick, and reduces the exposure time of the character edge of the character area when the character is thin. Make it longer than the exposure time in the text,
The printed matter inspection apparatus according to claim 1, wherein: Means for determining whether the character area is a lowercase area;
When the character area is a lower case area, the inspection unit generates difference data between the master image data and the character area (lower case area) of the inspection image data, and based on the difference data, Check for abnormal conditions,
The printed matter inspection apparatus according to any one of claims 1 to 6, A printed matter inspection method for inspecting a printed matter printed by a printing apparatus,
An inspection image acquisition step of acquiring the inspection image data by reading the printed matter;
A master image generation step of generating master image data from the original data of the printed matter;
A character region extraction step of extracting a character region of the master image data and the inspection image data;
Generating the difference data of the character area of the master image data and the inspection image data, and inspecting the abnormal state of the characters of the printed matter based on the difference data;
An adjustment step of adjusting parameters of a printing process of the printing apparatus according to an abnormal state of characters of the printed matter;
A printed matter inspection method characterized by comprising:

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