JP5910002B2 - Image reading apparatus, document size detection method, and document size detection program - Google Patents

Description

  The present invention relates to an image reading apparatus, a document size detection method, and a document size detection program. More specifically, the present invention relates to an image reading apparatus, a document size detection method, and a document size detection program that detect a document size at low cost and with high accuracy.

  In a book-type image reading device that reads an image of a document set on contact glass (document table) such as a scanner device, a copying device, a facsimile device, or a composite device, a light source, a mirror, etc. Based on read data obtained by moving a traveling body carrying optical components, irradiating a predetermined area of the contact glass with reading light, and photoelectrically converting the reflected light with a photoelectric conversion element such as a CCD (Charge Coupled Device). An original size is detected.

  Conventionally, an original size having means for arbitrarily changing the image data acquisition range in the main scanning direction and means for arbitrarily changing the image data acquisition interval in the sub-scanning direction and independently of the main scanning direction In the detection device, there is proposed a document size detection device in which the means for changing the image data acquisition range in the main scanning direction changes the acquisition range as the number of read lines increases (Patent Document 1). reference). In other words, this conventional technique uses a reading sensor for reading a document without using a dedicated photo sensor or the like to detect the document size, and increases the image data acquisition range as the number of reading lines increases. By changing, the accuracy is improved.

  However, in the above-described prior art, only the image data acquisition range is changed as the number of reading lines increases, and it is necessary to improve the document size with high accuracy and at low cost.

  That is, there are various images on the original, and if the original has a high density halftone dot image in a wide range, the image density is high. Therefore, it may be erroneously determined that there is no original and the original size may be erroneously determined.

  Accordingly, an object of the present invention is to detect a document size at low cost and with high accuracy.

In order to achieve the above object, an image reading apparatus according to claim 1 is an image reading unit that reads an image of a document on a platen and outputs analog read data; and an analog reading output by the image reading unit. digital conversion processing means for converting the digital read data to the data digitally converted, when the document size detection of the document placed on the document table, a predetermined number of said image reading means is the original table of predetermined size digitally converted digital read data, background and distinguishable image characteristics of the document in the main scanning direction end portion of the document includes at least image area separation processing by reading the document size detection region said digital conversion means Image processing means for performing image processing on the area digital read data, and the area digital image processed by the image processing means And a size detecting means for detecting the main scanning direction size of the document based on the read data, the image processing means, when the document reading, to the digital read data, an image including at least image area separation processing Image processing execution means for performing processing based on predetermined image processing parameters including image area separation processing parameters, and the image area separation processing parameters set in the image processing execution means at the time of document size detection and document reading When the document size is detected, the area digital read data is image-processed into area digital read data having image characteristics that can distinguish the end portion in the main scanning direction of the document from the background of the document. a parameter switching means for switching the image processing parameters, in that it comprises It is a symptom.

  According to the present invention, the document size can be detected inexpensively and with high accuracy.

1 is a schematic front view of an image reading unit of a color composite apparatus to which an embodiment of the present invention is applied. Front schematic enlarged view of the SDF unit. The front schematic enlarged view of the scanning optical system of an image reading part. The principal part block block diagram of a color compound apparatus. The block block diagram of a read signal processing part. FIG. 3 is a detailed block configuration diagram for reading signal processing. The block block diagram of an image process part. The block block diagram of a front | former stage image process part. The figure which shows an example of (gamma) table at the time of through and contrast emphasis. The block diagram of an image area separation processing unit. Explanatory drawing of a peak pixel. The figure which shows an example of (gamma) conversion curve and (gamma) look-up table. FIG. 6 is a block diagram of a pre-stage image processing unit showing only blocks that operate when reading a document. The block block diagram of a back | latter stage image process part. 6 is a flowchart showing document size detection processing. Explanatory drawing of a document size detection reading process. FIG. 4 is a diagram illustrating an example of a data storage state of a document size detection memory. 6 is a flowchart showing document detection processing. Explanatory drawing of the original detection process when a high density halftone dot exists in a detection area. An example of the main scanning size determination table is not shown. Explanatory drawing of a document size determination process. The figure which shows a document size determination table.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, since the Example described below is a suitable Example of this invention, various technically preferable restrictions are attached | subjected, However, The range of this invention is unduly limited by the following description. However, not all the configurations described in the present embodiment are essential constituent elements of the present invention.

  1 to 22 are diagrams showing an embodiment of an image reading apparatus, document size detection method, and document size detection program according to the present invention. FIG. 1 shows an image reading apparatus, document size detection method, and document according to the present invention. It is a front schematic block diagram of the image reading part 10 of the color composite apparatus 1 to which one Example of the size detection program is applied.

  In FIG. 1, an image reading unit (image reading apparatus) 10 is provided with a document reading table (document table) 12 at the top of a housing 11, and the document reading table 12 is usually provided with contact glass. ing. An openable / closable document pressing plate 13 is provided on the upper portion of the document reading table 12, and the document pressing plate 13 is configured to bring the document G set on the document reading table 12 into close contact with the contact glass of the document reading table 12. Press down on.

  A document transport unit 14 is disposed on the upper right side of the housing 11 of FIG. 1, and the document transport unit 14 includes an SDF (sheet through document feeder) unit 15 and a document tray 16. A document conveying stepping motor 17 is provided in the SDF unit 15, and a plurality of documents G are placed on the document tray 16 with the reading surface facing up.

  As shown in FIG. 2, the document conveying section 14 separates a plurality of documents G placed on the document tray 16 one by one by the SDF unit 15 and is rotated by a document conveying stepping motor 17. The separation roller 18 and the conveyance roller 19 pass through the document reading table 12 and are conveyed onto a paper discharge tray (not shown). The document transport unit 14 is provided with a white reference plate 20 for shading correction at the end of the document reading table 3 on the SDF unit 6 side. The document transport unit 14 is integrated with the document pressing plate 13, and when the document pressing plate 13 is opened, the document transport unit 14 is also opened and closed together.

  As shown in FIG. 2, an SDF window 12a is formed in the document conveyance path on the upper surface of the main body housing 2 where the document conveyance device 5 is disposed, and an upper portion of the position where the SDF window 12a is formed. In the SDF unit 15, a transmissive glass 12b and a white plate 15c are disposed. The white plate 15c is read when detecting whether or not dust or the like is attached to the optical path through the SDF window 12a and the transmission glass 12b, in particular, the SDF window 12a.

  Inside the housing 11, a scanning optical system (image reading means) 26 comprising a first traveling body 21, a second traveling body 22, a lens 23, a CCD (Charge Coupled Device) 24, a traveling body stepping motor 25, and the like is arranged. The first traveling body 21 is equipped with a light source 21a and a mirror 21b, and the second traveling body 22 is equipped with mirrors 22a and 22b.

  In the scanning optical system 26, the first traveling body 21 and the second traveling body 22 are moved in the horizontal direction (sub-scanning direction) by the traveling body stepping motor 25, and a light source 21a on the first traveling body 21, for example, a fluorescent lamp or the like. Irradiates the original G placed on the original reading table 12 with light, and the reflected light of the light reflected by the original G is reflected in the direction of the second traveling body 22 by the mirror 21b on the first traveling body 21. Then, the light incident from the first traveling body 21 is sequentially reflected by the mirror 22a and the mirror 22b on the second traveling body 22, and emitted in the direction of the lens 23. The lens 23 collects and irradiates the light incident from the second traveling body 22 on the CCD 24. The CCD 24 has one line of CCD elements arranged in a line in the main scanning direction as a plurality of photoelectric conversion elements in one dimension, and photoelectrically converts incident light incident from the lens 23 to obtain analog image data ( Image signal). Further, the scanning optical system 26 irradiates the white reference plate 18 with light, and the reflected light from the white reference plate 18 is incident on the CCD 24 in the same manner as described above, and is output from the CCD 24 as reference data for shading correction.

  Then, as shown in FIG. 3, the image reading unit 10 opens the document pressing plate 13 and reads the image of the document G placed on the document reading table 12 as shown in FIG. As shown, a plurality of documents G placed on the document tray 16 are rotated by driving a plurality of rollers 18 and 19 by a document transport stepping motor 17 of the SDF unit 15 using the document transport unit 14. There is an SDF mode in which an image of the original G is read by irradiating light to the conveyed original G from the light source 21a of the first traveling body 21 which is conveyed one by one to a predetermined reading position of the SDF window 12a and stopped.

  In the book mode, as shown in FIG. 3, the image reading unit 10 opens the document pressing plate 13 and sets the document G on the document reading table 12, turns on the light source 21a, first, the white reference The reading of the plate 18 is performed to obtain reference data for shading correction, and then the traveling body stepping motor 25 is driven to move the first traveling body 21 and the second traveling body 22 from the original G to the CCD 24. After moving in the sub-scanning direction with the length being constant and detecting the document size, the image of the document G on the document reading table 12 is read.

  In the SDF mode, as shown in FIG. 2, when a plurality of documents G are set on the document tray 16, the image reading unit 10 first turns on the light source 21 a and turns on the white reference plate 18 a. After performing the reading, the stepping motor 14 is driven to move the first traveling body 21 to the reading position of the SDF window 12a and stop. Next, the image reading unit 10 drives the document conveyance stepping motor 17 to separate the document G set on the document tray 16 one by one by the separation roller 17 and conveys the document G by the conveyance rollers 18 and 19. Then, the first traveling body 21 is conveyed to a predetermined reading position. At this time, the original G is conveyed at a constant speed, and the first traveling body 21 and the second traveling body 22 are stopped, and the original G is conveyed from the light source 21a on the first traveling body 21 through the SDF window 12a. Light from the original G reflected by the original G is reflected again by the mirror 21b and the mirrors 22a and 22b on the second traveling body 22 through the SDF window 12a, and passed through the lens 23 to the CCD 24. Incident light is subjected to photoelectric conversion by the CCD 24 to read an image of the original G.

  The color composite apparatus 1 has a circuit block configuration as shown in FIG. 4, and includes a CPU (Central Processing Unit) 31, a memory 32, a memory controller 33, a read signal processor 34, an image processor 35, and a write signal processor 36. , LD (Laser Diode: semiconductor laser) 37, LD drive unit 38, CCD 24, CCD drive circuit 39, light source 21a, light source driver 40, document transport motor driver 41, document transport stepping motor 17 for document transport, travel A body motor driver 42 and the traveling body stepping motor 25 for driving the traveling body are provided.

  The memory 21 stores various programs such as a basic processing program as the image reading unit 10 and a light source size detection program to be described later, and various data necessary for executing these various programs. Used for storage of memory and image data.

  The CPU (parameter switching means) 31 controls each unit of the color composite apparatus 1 and executes processing as the color composite apparatus 1 while using the memory 32 as a work memory based on a program in the memory 32. Then, a document size detection method described later is executed.

  The light source 21 a is controlled to be turned on / off by the light source driver 40 under the control of the CPU 31, and the CCD 24 is driven by the CCD driving unit 39 under the control of the CPU 31 to read the photoelectrically converted image data and the signal processing unit 34. Output to.

  The document conveying stepping motor 17 is driven by the document conveying motor driver 41 under the control of the CPU 31, and the traveling body stepping motor 25 is driven by the traveling body motor driver 42 under the control of the CPU 31.

As shown in FIG. 5, the read signal processing unit ( digital conversion processing means) 34 includes an analog video processing unit 51 and a shading correction processing unit 52.

  The analog video processing unit 51 receives an analog color image signal (analog read data) Sa output from the CCD 24, and the analog video processing unit 51 converts the analog color image signal Sa into a digital color image. The data (digital read data) is output to the shading correction processing unit 52.

  The shading correction processing unit 52 stores the color image data when the white reference plate 18 is read as reference data for shading correction in the internal RAM, and is digitally converted by the analog video processing unit 51 when the original G is read. The digital color image data is subjected to shading correction based on the reference data, and the digital color image data Sb after the shading correction is output to the image processing unit 35.

  The analog video processing unit 51 and the shading correction processing unit 52 of the read signal processing unit 34 are configured in block as shown in detail in FIG.

  That is, as shown in FIG. 6, the analog video processing unit 51 includes a preamplifier circuit 51a, a variable amplification circuit 51b, an A / D converter 51c, and the like. The shading correction processing circuit 52 includes a black arithmetic circuit 52a, a shading correction, and the like. An arithmetic circuit 52b and a line buffer 52c are provided.

  The image reading unit 10 focuses the reflected light irradiated on the original G on the original reading table 12 by the light source 21 a through the shading adjustment plate 27 and is focused on the CCD 24 by the lens 23 to form an image. In FIG. 6, a mirror for folding the reflected light is omitted for the sake of simplicity. Further, the shading adjustment plate 27 plays a role of adjusting the amount of light for eliminating the difference in the amount of reflected light between the central portion and the end portion of the CCD 24. That is, in the shading calculation process, if there is too much difference in the amount of reflected light between the central portion and the end portion of the CCD 24, only a calculation result including a lot of distortion can be obtained. After that, shading calculation processing is performed.

  The analog video processing unit 51 amplifies the analog color image signal Sa input from the CCD 24 by the preamplifier circuit 51a and the variable amplifier circuit 51b, and digitally converts it by the A / D converter 51c to correct the shading as digital color image data. The result is output to the black arithmetic circuit 52a of the processing unit 52.

  The shading correction processing unit 52 uses the black arithmetic circuit 52a for the digital color image data from the analog video processing unit 51 to vary the black level (electric signal when the amount of light is small) between the chips of the CCD 24 and between the pixels. This reduces the occurrence of streaks and unevenness in the black portion of the image and outputs the result to the shading correction arithmetic circuit 52b. The shading correction arithmetic circuit 52b performs irradiation based on the reference data held in the line buffer 52c. The digital color image data Sb is output to the image processing unit 35 by performing shading correction for correcting sensitivity variations of the system, the optical system, and the CCD 24.

  As shown in FIG. 7, the image processing unit (image processing means) 35 includes a pre-stage image processing unit 35a, a post-stage image processing unit 35b, and the like, and is configured by an ASIC (Application Specific Integrated Circuit).

  As shown in FIG. 8, the pre-stage image processing unit (image processing execution unit) 35a includes an interline correction processing unit 61, a document detection correction processing γ conversion processing unit 62, a document detection correction processing filter processing unit 63, and an image area. A separation processing unit 64, a γ conversion processing unit 65, a filter processing unit 66, a color conversion processing unit 67, and a scaling processing unit 68, and RGB (Red (Red), Green (Green), Blue color digital image data is input to the inter-line correction processing unit 61.

  The inter-line correction processing unit 61 corrects a line shift between RGB caused by a difference in RGB mounting positions of the CCD 24 that reads a color image. For example, the inter-line correction processing unit 61 corrects the amount of line deviation (line delay) between R and B and G and B when the B line is used as a reference.

  A document detection correction γ conversion processing unit (γ conversion processing means) 62 performs γ correction only when a document size is detected, and sets a through γ table as shown in FIG. The data is passed through and output to the document detection correction processing filter processing unit 63. That is, the original detection correction γ conversion processing unit 62 sets a through γ table (parameter) as shown in FIG. 9A by the CPU 31 when reading an original, and the image data from the interline correction processing unit 61 is set. The digital color image data is output to the document detection correction processing filter processing unit 63 as it is. Then, when detecting the document size, the document detection correction γ conversion processing unit 62 sets a γ table (parameter) for clarifying the contrast difference in image density as shown in FIG. The digital color image data from the correction processing unit 61 is subjected to γ correction to make it easier to detect halftone peaks, and the digital image data after γ correction is subjected to a document detection correction processing filter processing unit 63. Output to.

  A document detection correction processing filter processing section (filter processing means) 63 performs filter correction on the digital color image data only at the time of document size detection, and passes through the image data when reading the document, so that an image area separation processing section. 64. That is, in the document detection correction processing filter processing unit 63, the through filter coefficient (parameter) is set by the CPU 31, and the image data from the document detection correction γ conversion processing unit 62 is subjected to image area separation as it is. The data is output to the processing unit 64. Then, when detecting the document size, the document detection correction processing filter processing unit 63 sets a filter coefficient for increasing the sharpness by the CPU 31 in order to accurately detect the peak of the high density halftone dot. The digital color image data from the conversion processing unit 62 is subjected to filter processing that emphasizes the density level difference between the halftone dot peak image and surrounding pixels, and the image data is separated from the digital image after the filter processing. The data is output to the processing unit 64.

  In the image area separation processing unit 64, the CPU 31 switches the threshold value (image area separation processing parameter) between when the document size is detected and when the document is read, so that the digital color image data from the document detection correction processing filter processing unit 63 is converted. The image area separation process is performed on the digital color image data after the image area separation process is stored in the memory 71 when the document size is detected, and is output to the γ conversion processing unit 65 when the document is read. The image area separation unit 64 extracts a character area, a photographic area, a halftone dot area, and the like of the original G when reading the original, and an image area separation result for performing processing with parameters suitable for each area in the subsequent image processing unit 35b. And the s data in addition to the RGB image data is output to the γ conversion processing unit 65.

  Specifically, as shown in FIG. 10, the image area separation processing unit 64 includes a peak pixel detection unit 64a, a halftone dot region detection unit 64b, and a halftone dot region correction unit 64c. Is detected to determine whether it is a halftone dot (see Japanese Patent No. 3336046 and Japanese Patent No. 3518258). That is, the peak pixel detection unit 64a detects the peak pixel as shown in FIG. As shown in FIG. 11, the peak pixel means that the density level L of the central pixel is higher or lower than the density level of all the surrounding pixels, and the density level L of the central pixel is different from that of the central pixel. When the density levels a and b of the four pairs of pixels existing on the diagonal line are both | 2 × L−a−b |> TH (fixed threshold value), the center pixel has a peak. Let it be a pixel.

  The halftone dot area detection unit 64b determines that the block of interest is a halftone dot candidate area when 4 × 4 pixels are one block and there are two or more blocks including the peak pixel detected by the peak pixel detection unit 64a in the four blocks. The determination result and the digital color image data are output to the halftone dot region correction unit 64c.

  The halftone dot region correction unit 64c determines that four or more blocks are the halftone dot candidates detected by the halftone dot region detection unit 64b among the nine blocks centered on the target block, that is, the halftone dot region correction unit 64c has a certain size. If a dot area exists, the target block is set as a halftone dot area, and if not, correction processing is performed with the target block as a non-halftone dot area.

The image area separation processing unit 64 sets an image area separation processing parameter optimal for reading the original G by the CPU 31 during document reading, and performs image area separation processing using the image area separation processing parameter. If image area separation is performed using the image area separation processing parameters at the time of document reading, there may be cases where image area separation processing for appropriately detecting the document size cannot be performed.

  Therefore, in the color composite apparatus 1 according to the present embodiment, the CPU 31 causes the image area separation processing unit 64 to perform the image area separation processing by switching the image area separation processing parameter between when reading the original and when detecting the original size. . Specifically, when the CPU 31 sets a peak detection threshold (image area separation processing pattern) for detecting a peak of a high density halftone dot in the image area separation processing unit 64 at the time of document size detection, a character or the like is set as a halftone dot. Since there is a risk of erroneous detection, a threshold smaller than that at the time of reading the document is set in the image area separation processing unit 64 when the document size is detected.

  Then, the pre-stage image processing unit 35a performs γ conversion for document detection correction processing on the digital color image data so that the halftone dot detection by the image area separation processing unit 64 at the time of document size detection can be performed with higher accuracy. The processing unit 62 and the document detection correction processing filter processing unit 63 perform correction processing for contrast adjustment and filter processing.

  The pre-stage image processing unit 35a operates in the γ conversion processing unit 65, the filter processing unit 66, the color conversion processing unit 67, and the scaling processing unit 68 below the image area separation processing unit 63 only when reading a document.

  The γ conversion processing unit (γ conversion processing means) 65 sets the γ table according to the image area separation result in the image area separation processing unit 64 by the CPU 31, mainly adjusts the density, and performs digital processing. Color image data and s data are output to the filter processing unit 66. In this case, the γ conversion processing unit 65 is, for example, a γ table of a γ conversion curve as shown in FIG. 12A, and a γ lookup table as shown in FIG. Referring to, density adjustment is performed. In the case of FIG. 12B, when the input is “3”, the γ conversion processing unit 65 refers to the γ lookup table and outputs “D003”.

  A filter processing unit (filter processing means) 66 performs filter processing operations for the purpose of MTF correction, sharpening, and smoothing on the digital color image data that has been subjected to the γ conversion processing based on the s data. The data is output to the conversion processing unit 67.

  The color conversion processing unit 67 converts the color digital image data into a color space such as the output device LD37, for example, a CMYK color space, and outputs CMYK drawing data to the scaling processing unit 68. The processing unit 68 performs a scaling process for converting the read resolution to a desired resolution set by the operation display unit of the color multifunction apparatus 1, and outputs CMYK drawing data to the subsequent image processing unit 35b.

  That is, when reading a document, the pre-stage image processing unit 35a, under the control of the CPU 31, as shown in FIG. 13, the document detection correction processing γ conversion processing unit 62 and the document detection correction processing filter processing unit 63 Thus, the image data processing is performed only by the interline correction processing unit 61, the image area separation processing unit 64, the γ conversion processing unit 65, the filter processing unit 66, the color conversion processing unit 67, and the scaling processing unit 68. . In addition, when the image data is color image data, the pre-stage image processing unit 35a performs the above processing on each of the RGB components, and when the image data is monochrome image data, it uses the RGB G data path. The above process is performed for only one component.

  As shown in FIG. 8, the color multifunction apparatus 1 includes a document detection processing unit 72 that accesses the memory 71. The document detection processing unit (size detection unit) 72 is stored in the memory 71. The size of the original G in the main scanning direction is detected based on the existing digital color image data. The document detection processing unit 72 will be described in detail later.

  As shown in FIG. 14, the latter-stage image processing unit 35b includes a gradation conversion processing unit 81. The gradation conversion processing unit 81 receives CMYK image data from the scaling processing unit 68 of the previous-stage image processing unit 35a. Entered. The gradation conversion processing unit 81 converts CMYK, 8-bit, and 256 gradation CMYK image data into gradation data suitable for the write signal processing unit 36 according to the gradation capability of the write signal processing unit 36 in the subsequent stage. Once stored in the memory 32 via the memory controller 33.

  For example, the gradation conversion processing unit 81 performs gradation conversion processing by fixed threshold binarization when the image writing system after the write signal processing unit 36 in the subsequent stage can output up to 1 bit and 2 gradations. In this case, for example, when the binarization fixed threshold is “128”, the binarization process is performed on the CMYK image data input from the pre-stage image processing unit 35a under the following conditions.

“0” if 0 ≦ pixel data <128 is true
If 128 ≦ pixel data ≦ 255 is true, “1”.
Further, the gradation conversion processing unit 81 performs gradation conversion processing by quaternization of a fixed threshold value when the image writing system after the writing signal processing unit 36 in the subsequent stage can output up to 2 bits and 4 gradations. In this case, for example, when the quaternization fixed threshold is “128”, the quaternization process is performed on the CMYK image data input from the preceding image processing unit 35a under the following conditions.

“0” if 0 ≦ pixel data <64 is true
If 64 ≦ pixel data <128 is true, “1”.
If 128 ≦ pixel data <192 is true, “2”.
If 192 ≦ pixel data ≦ 255 is true, “3”.
The post-stage image processing unit 35 b stores the processed CMYK image data in the memory 32 via the memory controller 33.

  Returning to FIG. 4, the write signal processing unit 36 performs PWM modulation on the CMYK image data after gradation processing stored in the memory 32 and outputs it to the LD drive unit 38 in order to cause the LD 37 to emit light. . The LD drive unit 38 drives the LD 37 to blink on the basis of a signal from the write signal processing unit 36 to form an electrostatic latent image on a photoconductor (not shown).

  The color composite apparatus 1, in particular, the image reading unit 10 includes a ROM, an EEPROM (Electrically Erasable and Programmable Read Only Memory), an EPROM, a flash memory, a flexible disk, a CD-ROM (Compact Disc Read Only Memory), and a CD-RW. Execute the document size detection method of the present invention recorded on a computer-readable recording medium such as (Compact Disc Rewritable), DVD (Digital Versatile Disk), SD (Secure Digital) card, MO (Magneto-Optical Disc), etc. By reading a document size detection program to be read and introducing it into the memory 32 or the like, a document size detection method for detecting the document size in the main scanning direction at a low cost and with high accuracy using the CCD 24 of the scanning optical system 26 described later is executed. It is constructed as an image reading device. This document size detection program is a computer-executable program written in a legacy programming language such as assembler, C, C ++, C #, Java (registered trademark) or an object-oriented programming language, and is stored in the recording medium. And can be distributed.

  Next, the operation of this embodiment will be described. The image forming apparatus 1 according to the present embodiment uses the CCD 24 of the scanning optical system 26 that reads an image of the original G, and detects the original size at low cost and with high accuracy.

  When reading the image of the original G in the book mode, the color composite apparatus 1 detects the size of the original G in the main scanning direction using the CCD 24 of the scanning optical system 26 used for reading the original G.

  That is, in the color composite apparatus 1, when the document G is set on the document reading table 12 and the document size detection timing comes, that is, the open / close sensor (not shown) closes the document pressing plate 13 to a predetermined angle, for example, 30 °. When this is detected, as shown in FIG. 15, initialization is performed to perform initial settings for performing the document size detection operation (step S101), the first traveling body 21 and the second traveling body 22 are moved, and the document is moved. A size detection reading operation is performed (step S102).

  That is, as shown in FIG. 16 in which the original reading table 12 is seen from the original G, the color composite apparatus 1 is located at the home position HP on the starting side of the original reading table 12 when the original size is detected. After the traveling body 21 is moved to a preset detection start position KP, when the document size is detected, the moving direction of the traveling bodies 21 and 22 at the time of document reading (the right direction in FIG. 16) is opposite. The detection areas (document size detection areas) Ar1, Ar2, and Ar3 that are set in advance are read while moving in the movement direction (left direction in FIG. 16). The detection areas Ar1 to Ar3 are areas set in advance as areas where it is necessary to detect the presence or absence of the document G in order to determine the standard document size. FIG. 16 shows a case where three detection areas Ar1, Ar2, and Ar3 are provided, but the number of detection areas is not limited to three.

  The color composite apparatus 1 performs an original size detection reading operation, reads the detection areas Ar1 to Ar3 by the CCD 24, outputs analog image data to the read signal processing unit 34, and outputs an image to the digital color image by the analog video processing unit 51. In addition to conversion to data, signal processing is performed as necessary, and the result is output to the image processing unit 35.

  Then, the pre-stage image processing unit 35a of the image processing unit 35 corrects the line shift between the RGB caused by the difference between the RGB mounting positions of the CCD 24 where the interline correction processing unit 61 reads the digital color image, and then the original. When the detection correction γ conversion processing unit 62 detects the document size, it sets a γ table (parameter) for clarifying the contrast difference of the image density as shown in FIG. Γ correction is performed on the digital color image data from the image data to make it easier to detect halftone dot peaks, and the digital image data after γ correction is output to the document detection correction processing filter processing unit 63. The document detection correction processing filter processing unit 63 sets a filter coefficient for increasing the sharpness in order to accurately detect the peak of high density halftone dots when detecting the document size, and the document detection correction γ conversion processing unit 62. Is applied to the digital color image data from the digital image data from the digital image data to the image area separation processing unit 64 by applying a filter process for enhancing the density level difference between the halftone dot peak image and the surrounding pixels. Output. The image area separation processing unit 64 sets the threshold value at the time of document size detection (image area separation processing parameter), that is, a threshold value smaller than that at the time of document reading, and outputs from the document detection correction processing filter processing unit 63. Digital color image data is subjected to image area separation processing while preventing erroneous detection of characters and the like as halftone dots, and digital color image data after image area separation processing (region digital read data) Store in the memory 71.

  Therefore, in the memory 71, for example, as shown in FIG. 17, the read digital color image data Pat1 [1] to Pat1 [n + m], Pat2 [1] to Pat2 [n + m of each detection area Ar1 to Ar3. ], Pat3 [1] to Pat3 [n + m] are stored.

  In the color composite apparatus 1, under the control of the CPU 31, the document detection processing unit 72 causes the read digital color image data Pat1 [1] to Pat1 [n + m] and Pat2 [1] to Pat2 [n +] read from the memory 71. m], Pat3 [1] to Pat3 [n + m], document detection processing (step S103), main scanning document size determination processing (step S104), and document size determination processing (step S105) are sequentially performed.

  The color multifunction apparatus 1 performs the document detection process as shown in FIG. 18. The document detection process is roughly divided into a maximum line number setting process (step S201), an average value calculation process (step S210), and 2. It consists of a value determination process (step S220), an RGB determination process (step S230), and a halftone dot exclusion determination process (step S240).

  That is, when the color multifunction apparatus 1 enters the document detection process, as shown in FIG. 18, the document detection processing unit 72 first performs a maximum line number setting process for setting the maximum number of lines in the detection areas Ar1 to Ar3 to be read. (Step S201), and then an average value calculation process for calculating the average value of the RGB pixel values of the detection areas Ar1 to Ar3 is performed (Step S210). In this average value calculation process, first, the document detection processing unit 72 adds all the R pixels in the detection areas Ar1, Ar2, Ar3, and then divides the addition result by the number of pixels to calculate the average value of R (step Next, after adding all the G pixels in each of the detection areas Ar1, Ar2, and Ar3, the addition result is divided by the number of pixels to calculate an average value of R (step S212). Further, the document detection processing unit 72 adds all the B pixels of the right areas Ar1, Ar2, and Ar3, and then divides the addition result by the number of pixels to calculate an average value of B (step S213). For example, the document detection processing unit 72 calculates Pat1AveR ← (total of Pat1 [0] to Pat1 [m × n]) ÷ (m × n) for the R pixel in the detection area Ar1. The average value Pat1AveR is calculated. Similarly, the B and G components are calculated in the same manner as the average values Pat1AveG and Pat1AveB. Here, the RGB image data is 8-bit data, 0: bright, 255: dark.

  Next, the document detection processing unit 72 binarizes the average values Pat1AveR, Pat1AveG, Pat1AveB to Pat3AveR, Pat3AveG, Pat3AveB of each of the detection areas Ar1 to Ar3 calculated in the average value calculation process with respect to each RGB component. A binarization determination process for binarization is performed using PatTh (step S220). In the binarization determination process, the document detection processing unit 72 may set a binarization threshold value for each RGB when it is necessary to change the detection level for each of RGB. In the color composite apparatus 1, the average values Pat1AveR, Pat1AveG, Pat1AveB to Pat3AveR, Pat3AveG, and Pat3AveB of each detection area Ar1 to Ar3 are binarized with respect to each RGB component by using a common binarization threshold PatTh for RGB. To do. For example, PatTh = 32 is used as the binarization threshold PatTh. The document detection processing unit 72 uses the binarization threshold PatTh to binarize the RGB of the detection area Ar1 as Result1R, Result1G, and Result1B. If PatTh ≦ Pat1AveR, then Result1R ← 1: No document (Primary determination), if PatTh> Pat1AveR, Result1R ← 0: Document is present (primary determination) and binarized (step S221). Similarly, the detection areas Ar2 and Ar3 are binarized as Result2R, Result2G, Result2B and Result3R, Result3G, and Result3B (steps S222 and S223).

  When the binarization determination process is performed, the document detection processing unit 72 may have different binarization results for R, G, and B. If the determination is made using one component of RGB, an erroneous determination may be made depending on the document G. Therefore, the RGB determination process described below is performed on the binarized result of the RGB three components to determine the document size in the main scanning direction (step S230). In other words, the document detection processing unit 72 has dark data for all of R, G, and B when the logical product of the binarization results of R, G, and B in the detection areas Ar1 to Ar3 is true (1). Therefore, when it is determined that there is no document, and there is bright data in at least one of R, G, and B, the result of the logical product is false (0). Is determined.

  That is, the document detection processing unit 72 performs binarization determination on the detection area Ar1, for example, as follows.

If (Result1R & Result1G & Result1B) is Result1RGB: True (1), there is no document (secondary determination)
If (Result1R & Result1G & Result1B) is Result1RGB: False (0), there is a manuscript (secondary judgment)
Here, & indicates a logical product.

  The document detection processing unit 72 similarly performs the above processing on the detection area Ar2 and the detection area Ar3.

  Next, when there is high-density image information on the detection areas Ar1 to Ar3, the document detection processing unit 72, for example, in the area corresponding to the detection area Ar1 of the document G as shown in FIG. If there is high image information, the determination process up to the RGB determination process may make an erroneous determination. FIG. 19 shows a case where the document G is A4 size and there is a high image area indicated by hatching in the area corresponding to the detection area Ar1 of the document G in a state of covering the detection area Ar1. Therefore, the document detection processing unit 72 performs a halftone dot exclusion determination process (step S240) as follows.

  Specifically, the document detection processing unit 72 first determines the number of pixels determined as non-halftone dots (NumNotAmiTh) in the image area separation result of each pixel data of the detection areas Ar1 to Ar3 stored in the memory 71. Are counted as follows (step S241).

NumNotAmi ← (Number of pixels determined as non-halftone dots from PatNotAmi [0] to PatNotAmi [m × n])
Next, when a predetermined number of pixels, for example, 30% or more pixels are determined to be non-halftone areas, the document detection processing unit 72 sets the entire detection areas Ar1 to Ar3 as non-halftone dots. A threshold value NumNotAmiTh (for example, truncation of m × n × 0.3) is set, and non-halftone dot determination processing for determining whether or not the detection areas Ar1 to Ar3 are non-halftone dot areas as follows ( (Tertiary determination) is performed (steps S242 and S243).

  That is, the document detection processing unit 72 performs the following process on each of the detection areas Ar1 to Ar3 as the process of step S242.

If NumNotAmiTh ≦ NumNotAmi, Result1NotAmi ← 1 (non-halftone area)
If NumNotAmiTh> NumNotAmi, Result1NotAmi ← 0 (halftone dot area)
Next, as a process in step S243, the document detection processing unit 72 performs the following halftone dot exclusion determination process in the detection area Ar1, and ends the document detection process.

If (Result1RGB & Result1NotAmi) is true (1), Ar1 ← × No original (tertiary judgment)
If (Result1RGB & Result1NotAmi) is false (0), Ar1 ← ○ original exists (tertiary judgment)
The document detection processing unit 72 performs the above processing on the other detection areas Ar2 and Ar3, thereby referring to a main scanning size determination table as shown in FIG. Thus, the document size in the main scanning direction is determined as “182 mm or less”, “210 mm or less”, “257 mm or less”, “297 mm or less”.

  Returning to FIG. 15, the document detection processing unit 72 performs sub-scanning to detect the determination result of the main-scanning document size determination process (step S <b> 104) and the length of the document G in the sub-scanning direction as shown in FIG. 21. Based on the detection result of the size detection sensor 90, document size determination processing for determining the size of the document G is performed (step S105).

  As the sub-scanning size detection sensor (sub-scanning size detecting means) 90, for example, a reflection type photo sensor is used, and as shown in FIG. It is located at a position away from the document reference side with respect to the B5 size. In the case of a reflective photosensor, the sub-scanning size detection sensor 90 emits detection light from a light source (not shown) in the direction of the original G, and receives the intensity of reflected light depending on the presence or absence of the original G with a light receiving element. The presence or absence of the document G is detected. That is, the document detection processing unit 72 stores, for example, a document size determination table as shown in FIG. 22 in an internal memory or the like, and information on the reading results of the detection areas Ar1 to Ar3 of the CCD 24 (in FIG. Is the original and-is the original, and the detection result information of the sub-scanning size detection sensor 90 (in FIG. 22, ◯ is the original,-is no original, and a is the detection result of the sub-scanning size detection sensor 90. A document size determination process for determining a document size is performed with reference to a document size determination table based on whether a circle is a document and-is a document. For example, in FIG. 22, when the original detection processing unit 72 has all the detection areas Ar1 to Ar3 with a document and the detection result of the sub-scanning size detection sensor 90 is a document, the size of the document G is “A3”. If it is determined that there is a document only in the detection area Ar1 and the detection area Ar2, and the detection result of the sub-scanning size detection sensor 90 is that there is a document, it is determined that the size of the document G is “B4”.

  As described above, in the color composite apparatus 1 of this embodiment, the image reading unit 10 reads the image of the document G on the document reading table (document table) 12 and outputs analog read data (image). Reading means) 26, a reading signal processing unit (binarization processing means) 34 that binarizes analog reading data output from the CCD 24 of the scanning optical system 26 and converts it into digital reading data, and a document reading table 12. When detecting the document size of the placed document G, the CCD 24 of the scanning optical system 26 reads and reads a predetermined number of detection areas (document size detection areas) Ar1, Ar2, and Ar3 of a predetermined size on the document reading table 12. The area digital read data binarized by the signal processing unit 34 includes at least an image area separation process, and the main scanning direction end of the document is placed on the back of the document. An image processing unit (image processing means) 35 that performs image processing on area digital read data having image characteristics that can be distinguished from the image, and a size of the original G in the main scanning direction based on the area digital read data image-processed by the image processing unit 35 A document detection processing unit (size detection means) 72 for detecting the above.

  Accordingly, only the detection areas Ar1 to Ar3 necessary for detecting the document edge in the main scanning direction are read using the scanning optical system 26 for reading the image of the document G, and the document image is distinguished from the document edge and the background. Therefore, the image size can be detected at low cost and with high accuracy.

  Further, in the color composite apparatus 1 of this embodiment, the image reading unit 10 reads an image of the document G on the document reading table 12 and outputs analog read data, and the image reading processing step. A binarization processing step for binarizing the analog read data output in step S4 and converting it into digital read data, and when detecting the document size of the document placed on the document reading table 12, the image reading processing step Main scanning of the original including at least an image area separation process is performed on the area digital read data binarized in the binarization process step by reading a predetermined number of detection areas Ar1 to Ar3 having a predetermined size on the reading table 12. Image processing step for image processing of area end portion of image direction to region digital read data having image characteristics distinguishable from background of document , Running document size detection method with the size detection processing step of detecting the main scanning direction size of the original G on the basis of the region digital read data subjected to image processing in the image processing step.

  Accordingly, only the detection areas Ar1 to Ar3 necessary for detecting the document edge in the main scanning direction are read using the scanning optical system 26 for reading the image of the document G, and the document image is distinguished from the document edge and the background. Therefore, the image size can be detected at low cost and with high accuracy.

  Further, in the color composite apparatus 1 of the present embodiment, the image reading unit 10 reads an image of the document G on the document reading table 12 and outputs analog read data to the computer, and the image reading process. The binarization process for binarizing the analog read data output in the process and converting it into digital read data, and the original reading by the image reading process when detecting the original size of the original placed on the original reading table 12 An area digital read data binarized by the binarization process by reading a predetermined number of detection areas Ar1 to Ar3 of a predetermined size on the table 12 includes at least an image area separation process, and ends in the main scanning direction of the document Image processing is performed on the digital read data of a region having image characteristics that can be distinguished from the background of the original, and the image processing is performed by the image processing It is equipped with a document size detection program for executing the size detection process of detecting the main scanning direction size of the original G on the basis of the area digital read data.

  Accordingly, only the detection areas Ar1 to Ar3 necessary for detecting the document edge in the main scanning direction are read using the scanning optical system 26 for reading the image of the document G, and the document image is distinguished from the document edge and the background. Therefore, the image size can be detected at low cost and with high accuracy.

In the color composite apparatus 1 of the present embodiment, the image processing unit 35 performs predetermined image processing including image region separation processing parameters on image processing including at least image region separation processing on digitally read data when the document is read. An image processing parameter including an image area separation processing parameter set in the preceding image processing unit 35a is switched between a preceding image processing unit (image processing executing unit) 35a to be applied based on the image processing parameter and a document size detection time and a document reading time. At the same time, when the document size is detected, the CPU switches the area digital read data to an image processing parameter for image processing to the area digital read data having an image characteristic that can distinguish the end of the original G in the main scanning direction from the background of the original G. Parameter switching means) 31.

  Therefore, by simply switching the image processing parameters, the image processing for the original read image and the image processing for the area digital read data at the time of original size detection can be performed by the image processing unit 35, and the original size can be further reduced. It can be detected with high accuracy.

  Furthermore, in the color composite apparatus 1 of the present embodiment, the image processing unit 35 performs a filter process for sharpening and smoothing an image based on a filter parameter as the image processing parameter. A filter processing unit comprising a filter processing unit 63 and a filter processing unit 66, and a filter for increasing the image sharpness by the document detection correction processing filter processing unit 63 of the filter unit for the area digital read data at the time of document size detection. Processing is in progress.

  Therefore, by simply switching the image processing parameters, the image processing for the original read image and the image processing for the area digital read data at the time of original size detection can be performed by the image processing unit 35, and the original size can be further reduced. It can be detected with higher accuracy.

  Further, in the color composite apparatus 1 of this embodiment, the image processing unit 35 performs a γ conversion process for adjusting the density of an image based on a γ parameter as an image processing parameter. And a γ conversion processing unit 65, and at the time of document size detection, a contrast difference in image density is clarified by the document detection correction processing γ conversion processing unit 62 for the area digital read data. γ conversion processing is performed.

  Therefore, by simply switching the image processing parameters, the image processing for the original read image and the image processing for the area digital read data at the time of original size detection can be performed by the image processing unit 35, and the original size can be further reduced. It can be detected with higher accuracy.

  Further, in the color composite apparatus 1 of the present embodiment, the document detection processing unit 72 determines whether or not the detection areas Ar1 to Ar3 are halftone dot areas based on the area digital read data, and the determination result is obtained. Based on this, the size of the original G in the main scanning direction is detected.

  Therefore, even when there is a halftone dot, the edge of the original G can be detected appropriately, and the original size can be detected at a lower cost and with a higher degree of composition.

Further, in the color composite apparatus 1 of the present embodiment, the image processing unit 45 is the image region separation processing unit 64 and uses the threshold value for halftone dot separation peak detection as the image region separation processing parameter. The document detection processing unit 72 determines whether or not the detection regions Ar1 to Ar3 of the document G are halftone dot regions based on the digital read data obtained by the image region separation processing unit 64. Thus, the size of the original G in the main scanning direction is detected based on the determination result.

  Therefore, even when there is a halftone dot, the edge of the original G can be detected appropriately, and the original size can be detected at a lower cost and with a higher degree of composition.

  Further, in the color composite apparatus 1 of the present embodiment, the image reading unit 10 detects a position of the end portion of the document G on the document reading table 12 in the sub-scanning direction (sub-scanning size detecting means). The document detection processing unit 72 detects the size and orientation of the document G based on the size in the main scanning direction and the end position in the sub scanning direction detected by the sub scanning size detection sensor 90. ing.

  Accordingly, the document size and orientation can be detected inexpensively and accurately.

  The invention made by the present inventor has been specifically described based on the preferred embodiments. However, the present invention is not limited to that described in the above embodiments, and various modifications can be made without departing from the scope of the invention. It goes without saying that it is possible.

DESCRIPTION OF SYMBOLS 1 Color compound apparatus 10 Image reading part 11 Case 12 Original reading stand 12a SDF window 12b Transmission glass 13 Original holding plate 14 Original conveyance part 15 SDF unit 15c White plate 16 Original tray 17 Original conveyance stepping motor 18 Separation roller 19 Conveyance roller 20 White Reference plate 21 First traveling body 21a Light source 21b Mirror 22 Second traveling body 22a, 22b Mirror 23 Lens 24 CCD
25 traveling body stepping motor 26 scanning optical system 31 CPU
32 memory 33 memory controller 34 read signal processing unit 35 image processing unit 35a front image processing unit 35b rear image processing unit 36 write signal processing unit 37 LD
38 LD drive unit 39 CCD drive circuit 40 Light source driver 41 Document transport motor driver 42 Traveling body motor driver 51 Analog video processing unit 52 Shading correction processing unit 61 Interline correction processing unit 62 Document detection correction processing gamma conversion processing unit 63 Document detection Correction processing filter processing unit 64 Image area separation processing unit 65 γ conversion processing unit 66 Filter processing unit 67 Color conversion processing unit 68 Scaling processing unit 71 Memory 72 Document detection processing unit 81 Gradation conversion processing unit 90 Sub-scanning size detection sensor G manuscript

JP 2007-60004 A

Claims (8)

Image reading means for reading an image of a document on a platen and outputting analog read data;
Digital conversion processing means for digitally converting analog read data output from the image reading means into digital read data;
When detecting the document size of the document placed on the document table, the image reading unit reads a predetermined number of document size detection areas of a predetermined size on the document table, and is digitally converted by the digital conversion processing unit . the digital read data, image processing means for image processing in the main scanning direction end portion of the document includes at least image area separation processing region digital data read distinguishable image characteristics and background of the document,
Size detecting means for detecting the size of the original in the main scanning direction based on the area digital read data image-processed by the image processing means;
Equipped with a,
The image processing means includes
Image processing execution means for performing image processing including at least image area separation processing on the digital read data based on predetermined image processing parameters including image area separation processing parameters when reading a document;
The image processing parameters including the image area separation processing parameters set in the image processing execution unit are switched between when the document size is detected and when reading the document. A parameter switching means for switching an image processing parameter for image processing to an area digital read data having an image characteristic distinguishable from the background of the document in the main scanning direction end;
Image reading apparatus characterized in that it comprises a. The image processing means includes
Filter processing means for performing filter processing for sharpening and smoothing an image based on a filter parameter as the image processing parameter ,
2. The image reading apparatus according to claim 1 , wherein when the document size is detected , the area digital read data is subjected to a filter process for increasing a sharpness of the image by the filter processing unit. The image processing means includes
Γ conversion processing means for performing γ conversion processing for adjusting image density based on the γ parameter as the image processing parameter,
3. The gamma conversion processing for clarifying a contrast difference in image density by the gamma conversion processing means on the area digital read data when the document size is detected. Image reading device. The size detecting means includes
It is determined whether or not the document size detection area is a halftone dot area based on the area digital read data, and based on the determination result whether or not the document size detection area is a halftone dot area, The image reading apparatus according to claim 1, wherein a size in a main scanning direction is detected . The image processing means includes
As the image area separation processing parameter, image processing is performed on the area digital read data using a threshold value for peak detection of halftone dot separation,
The size detecting means includes
It is determined whether or not the document size detection region is a halftone dot region based on the region digital read data subjected to image processing by the image processing means, and whether or not the document size detection region is a halftone dot region. 5. The image reading apparatus according to claim 1, wherein a size of the original in the main scanning direction is detected based on a determination result. The image reading device includes:
A sub-scanning size detecting means for detecting an end position of the original on the original table in the sub-scanning direction;
2. The size detection unit detects the size and orientation of the document based on a size in the main scanning direction and an end position in the sub scanning direction detected by the sub scanning size detection unit. The image reading apparatus according to claim 5.   An image reading processing step for reading an image of a document on a platen and outputting analog read data;
  A digital conversion processing step for digitally converting the analog read data output in the image reading step into digital read data;
  When the document size of the document placed on the document table is detected, a predetermined number of document size detection areas of a predetermined size on the document table are read in the image reading step and digitally converted in the digital conversion processing step. An image processing step for image-processing digital read data into area digital read data having an image characteristic that includes at least an image area separation process and distinguishable from a background of the original at an end in the main scanning direction of the original;
  A size detection processing step for detecting a size of the document in the main scanning direction based on the area digital read data image-processed in the image processing step;
  Have
  The image processing step includes
  An image processing execution step of performing image processing including at least image area separation processing on the digital read data based on predetermined image processing parameters including image area separation processing parameters when reading a document;
  The image processing parameters including the image area separation processing parameters set in the image processing execution step are switched between when the document size is detected and when the document is read, and when the document size is detected, the area digital read data is converted into the document. A parameter switching step for switching an image processing parameter for image processing to an area digital read data having an image characteristic in which the main scanning direction end can be distinguished from the background of the document;
  A method for detecting a document size. On the computer,
An image reading processing step for reading an image of a document on a platen and outputting analog read data;
A digital conversion processing step for digitally converting the analog read data output in the image reading step into digital read data;
When the document size of the document placed on the document table is detected, a predetermined number of document size detection areas of a predetermined size on the document table are read in the image reading step and digitally converted in the digital conversion processing step . the digital read data, and an image processing step of the image processing in the main scanning direction end portion of the document includes at least image area separation processing region digital data read distinguishable image characteristics and background of the document,
A size detection processing step for detecting a size of the document in the main scanning direction based on the area digital read data image-processed in the image processing step;
And execute
The image processing step includes
An image processing execution step of performing image processing including at least image area separation processing on the digital read data based on predetermined image processing parameters including image area separation processing parameters when reading a document;
The image processing parameters including the image area separation processing parameters set in the image processing execution step are switched between when the document size is detected and when the document is read, and when the document size is detected, the area digital read data is converted into the document. A parameter switching step for switching an image processing parameter for image processing to an area digital read data having an image characteristic in which the main scanning direction end can be distinguished from the background of the document;
Allowed to execute document size detection program characterized Rukoto.

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