Image reading device, control method thereof, and program

Abstract

To provide an image reading device which executes processing of image data in a coupling region by suppressing increase in a circuit scale, a control method of the same and a program.SOLUTION: A method comprises the steps of: storing and reading image data obtained by reading a prescribed line of a document in a plurality of line image sensors arranged so as to overlap each other in an image sensor adjacent to a portion of a reading region; generating the image data of an overlapping region by synthesizing the first image data of the overlapping region in the one image sensor and the second image data of the overlapping region in the other image sensor; generating the image data of a prescribed line of a document on the basis of the stored image data of a region other than the overlapping region; and generating the image data of the document by repeatedly executing the aforementioned steps in the sub-scanning direction of the document.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to an image reading apparatus, a control method thereof, and a program. [Background technology]

[0002] Conventionally, image reading devices have been known that have multiple image sensors arranged in a staggered pattern in two rows to read images recorded on media such as large-format paper. By using multiple image sensors, such as A4-sized ones, image reading devices capable of reading large-format paper can be manufactured inexpensively. In such a system using multiple image sensors, it is necessary to provide an image processing means for each of the installed image sensors, and ultimately to combine the image data from the multiple image sensors to form large image data for one line. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-022062 Summary of the Invention [Problem to be solved by the invention]

[0004] In Patent Document 1, one controller reads three image sensors (CIS1-3) so that adjacent sensors partially overlap in the main scanning direction, and performs a combining process to stitch together the image data. Sensor CIS2 is arranged upstream in the sub-scanning direction, and sensors CIS1 and CIS3 are arranged downstream in a staggered pattern with a certain interval between them. Here, when combining image data from two image sensors (CIS1, CIS3), a leading image sensor (CIS2) and a trailing image sensor, the image data acquired by the leading image sensor is stored in an interpolation buffer, and image data in the combined regions of the image data acquired by the trailing image sensors is combined and output.

[0005] As described above, in conventional devices, image data in the combined area had to be temporarily stored in a buffer after image data acquired by one of the CISs was read from memory, etc. This required a storage buffer with the maximum width of the combined area, which resulted in a problem of large circuit size. Also, image data from the next image sensor to be processed could not be read from memory or processed until image data from the entire area of ​​one image sensor had been read from memory. This resulted in a problem of slower processing speed.

[0006] An object of the present invention is to solve at least one of the problems of the prior art.

[0007] An object of the present invention is to provide a technique that can process image data in a combined region while suppressing an increase in circuit scale. [Means for solving the problem]

[0008] In order to achieve the above object, an image reading device according to one aspect of the present invention has the following configuration: a plurality of line image sensors arranged to have overlapping regions in which the reading regions of adjacent image sensors partially overlap in a main scanning direction in which the document is read; a storage means for storing image data obtained by reading predetermined lines of the document by the plurality of line image sensors; a first readout means for reading out image data obtained by reading with a first line image sensor among the plurality of line image sensors from the storage means; a second reading means for reading, from the storage means, image data obtained by reading with a second line image sensor adjacent to the first line image sensor in the main scanning direction; Read out before Recorded picture Image data against a discrimination means for discriminating image data corresponding to a plurality of overlapping areas; The preceding image corresponding to each of the plurality of overlapping areas determined by the determining means Record number 1-line image sensor The aforementioneda combining means for combining the first image data and the second image data obtained by each of the second line image sensors to generate image data for each of the plurality of overlapping regions; a generating means for generating image data of the predetermined line of the document based on image data obtained by excluding image data of the plurality of overlapping regions from the image data stored in the storing means and the image data of each of the plurality of overlapping regions generated by the combining means; and control means for controlling the storage means, the determination means, the synthesis means, and the generation means to repeatedly execute processing for a predetermined line of the document in the sub-scanning direction of the document. [Effects of the Invention]

[0009] According to the present invention, it is possible to suppress an increase in the circuit scale and to process image data in a combined region.

[0010] Other features and advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings, in which the same or similar elements are designated by the same reference numerals. [Brief explanation of the drawings]

[0011] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. [Figure 1] 1A and 1B are an external perspective view and a schematic cross-sectional view of a reading device (scanner) according to an embodiment. [Figure 2] FIG. 2 is a diagram illustrating the configuration of a line image sensor according to the embodiment. [Figure 3] FIG. 2 is a block diagram illustrating the hardware configuration of a control system in the scanner according to the embodiment. [Figure 4] FIG. 2 is a block diagram illustrating the internal configuration of an ASIC according to the embodiment. [Figure 5] FIG. 2 is a block diagram illustrating the configuration of a combination processing unit according to the embodiment. [Figure 6]10 is a flowchart illustrating one line of data processing performed by a first buffer reading unit according to the embodiment. [Figure 7] FIG. 10 is a diagram for explaining the outline of a flow in which an internal merge processing unit 514 according to the embodiment processes image data from a first buffer reading unit, a second buffer reading unit, and a mask data reading unit. [Figure 8] 10A and 10B are diagrams showing an example of the combination gravity ratio and mask data in the combined region of the first CIS and the second CIS in the image data combination process in the internal combination processor according to the embodiment. [Figure 9] 1 is an external perspective view of an image forming apparatus having a large-format image reading function according to an embodiment; [Figure 10] FIG. 10 is a diagram showing an example of an arrangement of CISs according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the invention according to the claims. Although the embodiments describe multiple features, not all of these multiple features are necessarily essential to the invention, and multiple features may be combined arbitrarily. Furthermore, in the accompanying drawings, the same reference numerals are used to designate identical or similar components, and redundant explanations will be omitted. Note that the following embodiments will be described using a sheet-fed image reading device (hereinafter referred to as a scanner) as an example, but the scope of application of the present invention is not limited to this, and it can also be applied to a flatbed image reading device.

[0013] FIG. 1A is a perspective view showing the appearance of a sheet-fed scanner 100 according to an embodiment.

[0014] As shown in FIG. 1(a), scanner 100 has document feed slot 101 and document feed tray 102 on the front side of the main body. A user places the leading edge of a document on document feed tray 102 so that the center of the document is positioned in the center of the document feed slot, and then slides the document over document feed tray 102 to insert it into document feed slot 101. Document feed slot 101 is designed to allow for a certain degree of misalignment and tilt during insertion relative to the width of the document in the main scanning direction that can be read by scanner 100. The configuration of the document feed path will be described in detail with reference to FIG. 1(b).

[0015] Scanner 100 has an operation unit 103 including physical keys and a liquid crystal panel on the top surface of the main body, and the user can set reading conditions and input document size via this operation unit 103. In addition, a top cover 104 is provided on the top surface of scanner 100, and opening top cover 104 upward allows access to the reading unit, etc., allowing maintenance of the main body to be performed.

[0016] FIG. 1B is a schematic cross-sectional view showing the internal configuration of the scanner 100 according to the embodiment.

[0017] In FIG. 1B, the left side is the upstream side of the document feed and the right side is the downstream side, and the document 110 is transported in the y-axis direction. The document 110 fed by the user along the document feed tray 102 passes through a flat transport path and is ejected from the rear of the main body. The document detection sensor 105 detects the insertion of the document 110. When the insertion of the document 110 is detected, the upstream document transport roller 108 is driven to rotate, and the document 110 is drawn into the transport path. The edge detection sensor 112 is used to detect the leading edge of the document 110 drawn into the transport path by the rotation of the upstream document transport roller 108. The detection result of the edge detection sensor 112 is used to determine the reading start position of the document 110, detect the position of the trailing edge of the document 110, etc. Inside the transport path, the document 110 passes between the glass plate 109 and the document pressing plate 111. The document pressing plate 111 serves to press the document 110 against the glass plate 109 with a predetermined pressure.

[0018] The CIS 106 is a line image sensor (hereinafter, CIS) whose reading surface is arranged in the main scanning direction. The reading surface of the CIS 106 faces the glass plate 109, and is designed so that the reading focal position is located at the contact surface between the original 110 and the glass plate 109. The downstream original transport roller 107 is configured to be driven by the upstream original transport roller 108 via a belt (not shown), and has the role of ejecting the original 110 downstream after it has passed through the area pressed against the glass plate 109 by the original presser plate 111. The scanner 100 further has motors (not shown) for rotating the detection sensors and the upstream original transport roller 108, a circuit board for controlling the CIS 106 and the operation unit 103, etc.

[0019] 2(a) is a diagram illustrating the configuration of a line image sensor (CIS) 106 according to an embodiment. The CIS 106 has five CISs arranged in two rows in a staggered pattern, and these CISs are arranged parallel to each other in the main scanning direction so that the reading areas of adjacent CISs in the main scanning direction partially overlap.

[0020] The reading portions of the right end of the first CIS 200 and the left end of the second CIS 201 overlap in the main scanning direction. This overlapping portion is referred to as a first overlapping region 205. Similarly, the reading portions of the right end of the second CIS 201 and the left end of the third CIS 202 overlap in the main scanning direction. This overlapping region is referred to as a second overlapping region 206. The overlapping region increases as the number of CISs increases. When a fourth CIS 203 and a fifth CIS 204 are added, bringing the total to five, a third overlapping region 207 and a fourth overlapping region 208 exist, as shown in FIG. 2(a).

[0021] FIG. 2( b ) is an enlarged view of the first overlapping region 205 .

[0022] The left and right ends of each CIS have invalid pixel regions where acquired image data is assumed to be discarded. These regions are designated as the left-end invalid pixel region 209 and the right-end invalid pixel region 210, respectively. The first overlapping region 205, excluding the left-end invalid pixel region 209 and the right-end invalid pixel region 210, is designated as the first combined region 211. This first combined region 211 is a region where the image data output from the first CIS 200 and the second CIS 201 are combined based on ratio data to create a single image data. Such invalid pixel regions and combined regions exist for each overlapping region. However, depending on the internal configuration of the CIS, pixels at both ends may also be treated as valid pixels. In such cases, either the left-end invalid pixel region 209, the right-end invalid pixel region 210, or both may not exist.

[0023] FIG. 3 is a block diagram illustrating the hardware configuration of a control system in the scanner 100 according to the embodiment.

[0024] The conveyance motor 300 is controlled by a system ASIC (hereinafter simply referred to as ASIC) 301 via a motor driver 302, and rotates the upstream conveyance rollers 108 and downstream conveyance rollers 107 to control the conveyance of the original. The outputs of the original detection sensor 105 and the edge detection sensor 112 are input to the ASIC 301. The ASIC 301 determines the drive timing of the multiple CISs 200-204 based on changes in the output signals of these sensors and the state of the conveyance motor 300, and controls the multiple CISs 200-204. Analog signals representing image data obtained by scanning the original document using the multiple CISs 200-204 are converted into digital signals by each A / D converter 306 and input to the ASIC 301. The ASIC 301 processes the digital data converted by the A / D converter 306 and can transmit the digital data as image data to an external device connected via an IF unit 303 via a USB or LAN. The power supply unit 305 generates the voltage required for each unit and supplies power.

[0025] FIG. 4 is a block diagram illustrating the internal configuration of the ASIC 301 according to the embodiment.

[0026] Image data from each CIS is converted from an analog signal to a digital signal by the A / D converter 306 and input. The ASIC 301 receives the image data input from the A / D converter 306 line by line and outputs it to a read image buffer 410 in the external memory 409 via the read image control unit 401. The first DMAC 402 in the ASIC 301 then reads the received image data line by line from the read image buffer 410. Because the CISs arranged in a staggered pattern are offset in the sub-scanning direction as shown in FIG. 2, the even-numbered CIS that reads first and the odd-numbered CIS that reads next have different read timings for the same line. Taking this offset in read timing into account, the first DMAC 402 reads image data from the read image buffer 410 in the external memory 409 when one line of image data from each CIS is collected.

[0027] The image data thus read by the first DMAC 402 is filtered by a filter processing unit 403, which is a processing circuit for reducing noise contained in the image data from the CIS and changing the spatial frequency. After filtering the image data, the filter processing unit 403 stores the processed image data in a tilt processing buffer 411 in the external memory 409. The image data stored in the tilt processing buffer 411 is then processed by a tilt correction processing unit 404, which corrects the tilt of the image data caused by the tilt of each CIS due to installation tolerances. The image data that has been filtered and tilt corrected in this way is stored in an internal memory 405 of the ASIC 301. In the following description, the image data obtained by the CIS reading an image and then processed and stored in the internal memory 405 may be referred to as "CIS image data."

[0028] The image data for one line (predetermined line) of the CIS stored in the internal memory 405 in this way is read out by the combining processing unit 406. The read image data is combined to form image data for one line of the original. The digital image data for one line of the original generated by the combining processing is written into the interface buffer 412 of the external memory 409 by the second DMAC 407. The image data for one line written into the interface buffer 412 is read out by the interface control unit 408 and output from the external interface 413.

[0029] In this way, image data for each line is generated and output as the document is transported, and finally, image data representing the image of the document is output.

[0030] The ASIC 301 also has an operation instruction unit 414, which has a processing start instruction function that instructs a specific block to start processing, and a processing end reception function that receives a processing end notification from a specific block. The operation instruction unit 414 also uses these functions to operate each block sequentially. The ASIC 301 also has a CPU 400, which is responsible for setting the setting values ​​of each processing block and issuing instructions to start overall processing.

[0031] FIG. 5 is a block diagram illustrating the configuration of the combination processing unit 406 according to the embodiment.

[0032] The first memory read control unit 503 reads image data of odd-numbered CISs from the internal memory 405, and the second memory read control unit 504 reads image data of even-numbered CISs from the internal memory 405. Therefore, in the case of a scanner consisting of five CISs, the image data of the first CIS 200, the third CIS 202, and the fifth CIS 204 are read from the internal memory 405 by the first memory read control unit 503, and the image data of the second CIS 201 and the fourth CIS 203 are read from the internal memory 405 by the second memory read control unit 504.

[0033] Upon receiving a processing start instruction notification from the operation instruction unit 414, the first memory read control unit 503 and the second memory read control unit 504 request the memory access arbitration unit 501 to read image data from the internal memory 405. The memory access arbitration unit 501 performs read processing in order for the read requests from each read control unit to prevent access conflicts, and passes the read image data to the corresponding memory read control unit. In this embodiment, the configuration is such that image data for four pixels is read in one read from the internal memory 405.

[0034] The first memory read control unit 503 organizes the read image data into pixel data for each pixel, and processes it in the order of the first CIS 200, the third CIS 202, and the fifth CIS 204. It continues to pass the pixel data to the first buffer 506 until processing of one line of image data is complete. The second memory read control unit 504 similarly organizes the read image data into pixel data for each pixel, and processes it in the order of the second CIS 201 and the fourth CIS 203, and continues to pass the pixel data to the second buffer 507 until processing of one line of image data is complete. When the pixel data stored in the first buffer 506 becomes full, the first memory read control unit 503 stops passing pixel data to the first buffer 506. At the same time, it temporarily stops reading pixel data from the internal memory 405. Similarly, when the pixel data stored in second buffer 507 becomes full, second memory read control unit 504 stops passing pixel data to second buffer 507 and simultaneously temporarily stops reading pixel data from internal memory 405. Then, when a free area of ​​four or more pixels occurs in first buffer 506, first memory read control unit 503 resumes the pixel data read process. Similarly, when a free area of ​​four or more pixels occurs in second buffer 507, second memory read control unit 504 resumes the pixel data read process.

[0035] The pixel data stored in the first buffer 506 is read by a first buffer reading unit 511, and the pixel data in the second buffer 507 is read by a second buffer reading unit 512. The first buffer reading unit 511 and the second buffer reading unit 512 determine whether the read pixel data is a pixel in an invalid pixel area (invalid pixel), and if determined to be an invalid pixel, discard the pixel data without passing it to the internal merge processing unit 514. To determine whether a pixel is an invalid pixel or a valid pixel, the count values ​​(counting values) of a first counter 509 and a second counter 510 are referenced. The first counter 509 counts the number of pixels read from the first buffer 506, and the second counter 510 counts the number of pixels read from the second buffer 507. The count values ​​of these counters are compared with values ​​indicating the invalid pixel area of ​​each CIS specified by the CPU 400 to determine whether the read pixel data is an invalid pixel. Details of the processing of the buffer reading units 511 to 513 will be described later.

[0036] The process of combining the image data from each CIS uses mask data. The mask data is stored in advance in a mask memory 500 and read out by a mask memory read control unit 505. In this embodiment, four pixels of mask data are read out at a time from the mask memory 500. Upon receiving a processing start instruction notification from the operation instruction unit 414, the mask memory read control unit 505 requests the mask memory access arbitration unit 502 to read the mask data from the mask memory 500. The mask memory access arbitration unit 502 processes write and read requests in order to prevent access conflicts, including access from the CPU 400, and the read mask data is passed to the mask memory read control unit 505. The mask memory read control unit 505 organizes the mask data into pixel-by-pixel mask data and stores it in a mask buffer 508.

[0037] The mask data reading unit 513 performs processing based on the count value of the first counter 509 and the count value of the second counter 510. That is, when the count values ​​of the first counter 509 and the second counter 510 both indicate a combined region, the mask data reading unit 513 passes the mask data to the internal combine processing unit 514 at the same time that the first buffer reading unit 511 and the second buffer reading unit 512 pass the image data to the internal combine processing unit 514, respectively. The internal combine processing unit 514 forms one image data from two pieces of image data in the combined region based on the mask data and sends the image data to the DMAC output unit 515.

[0038] Furthermore, if either the pixel data read by the first buffer reading unit 511 or the second buffer reading unit 512 is valid, the pixel data is passed as is to the DMAC output unit 515. The DMAC output unit 515 organizes the pixel data processed by the internal join processing unit 514, and passes the pixel data to the second DMAC 407 so as to comply with the interface protocol of the second DMAC 407.

[0039] In this embodiment, image data for four pixels is acquired in one read from the internal memory 405. For this reason, the first buffer 506 and the second buffer 507 are desirably sized to be able to store image data for at least eight pixels, taking into account the four pixels of image data received and the image data to be output. The sizes of the first buffer 506 and the second buffer 507 should be determined appropriately depending on the number of pixels read in one read from the internal memory 405 and the processing speed of the image processing blocks subsequent to the internal join processor 514. The same applies to the mask buffer 508 that stores mask data.

[0040] FIG. 6 is a flowchart illustrating one line of data processing performed by the first buffer reading unit 511 according to the embodiment.

[0041] When the first buffer reading unit 511 starts processing, it determines in S600 whether pixel data is stored in the first buffer 506. If pixel data is not stored, it waits in S600 until pixel data is stored in the first buffer 506. Once pixel data is stored in the first buffer 506, the process proceeds to S601. In S601, pixel data for one pixel is read from the first buffer 506. In response to this pixel data being read, the first counter 509 counts up once (increases the count value by 1) in S602. Next, the process proceeds to S603, where the count value of the first counter 509 is referenced to determine whether the count value indicates a valid pixel or a pixel in an invalid pixel area. As described above, the value indicating whether the pixel is valid or invalid is referenced to a value previously specified by the CPU 400. If the pixel is determined to be an invalid pixel, the process proceeds to S610, where the pixel data is discarded. In other words, the pixel data is discarded without being passed to the internal merge processing unit 514, which is a subsequent processing block, and the process proceeds to S607.

[0042] If the pixel is determined to be a valid pixel in S603, the process proceeds to S604. In S604, it is determined whether the pixel data read out in S601 is a pixel of a combined region by referring to the count value of the first counter 509. As described above, the value indicating whether the pixel is a pixel of a combined region is determined by referring to a value designated in advance by the CPU 400. If it is determined in S604 that the pixel is a pixel of a combined region, the process proceeds to S605, and if it is determined that the pixel is not a pixel of a combined region, the process proceeds to S606. In S605, it is determined whether preparation of pixel data in the second buffer reading unit 512 is complete. In determining whether pixel data preparation is complete, it is determined whether pixel data processing up to the pixel of the combined region is complete by referring to the count value of the second counter 510.

[0043] Since the processing of pixel data by the second buffer read unit 512 is also executed in parallel in the same manner as the processing flow described for the first buffer read unit 511, the count value of the second counter 510 is incremented as image processing progresses. The first buffer read unit 511 waits in the processing of S605 until the second buffer read unit 512 completes processing of the pixel data up to the combined region. Then, when the second buffer read unit 512 completes processing of the pixel data up to the pixels of the combined region, the processing of the first buffer read unit 511 advances from S605 to S606. In S606, the first buffer read unit 511 passes the pixel data read by it to the internal merge processor 514. If the pixel is determined to be a pixel in the combined region in S604, the timing of passing this pixel data is the same as the timing of passing the pixel data from the second buffer read unit 512 to the internal merge processor 514. The timing at which the mask data is passed from the mask data reading unit 513 to the internal join processing unit 514 is also the same. Therefore, the two pixel data and the mask data are passed to the internal join processing unit 514 at the same time.

[0044] On the other hand, if the pixel is not determined to be a pixel in a combined region in S604, the process proceeds to S606, where only the pixel data is passed from the first buffer reading unit 511 to the internal combine processing unit 514. When the process of S606 is completed, the process proceeds to S607. In S607, it is determined whether processing of the image data of all pixels comprising one CIS has been completed. Here, the count value of the first counter 509 is referenced, and if that count value matches the total number of pixels per CIS, it is determined that processing of the image data of all pixels comprising one CIS has been completed. If it is determined that processing of the image data of all pixels per CIS has been completed, the process proceeds to S608, where the count value of the first counter 509 is reset, and the process proceeds to S609. On the other hand, if the processing is not completed, the process proceeds to S600, where the same processing as before is performed to process the data of the next pixel.

[0045] In S609, it is determined whether the processing of image data for all CISs has been completed. In other words, it is determined whether the processing of image data for one line has been completed. If the processing of image data for one line is not yet completed, the process proceeds to S611, where the processing of image data for the next CIS proceeds. In other words, when the processing of image data for the first CIS 200 is completed, the process proceeds to the processing of image data for the third CIS 202. Then, when the processing of image data for the third CIS 202 is completed, the process proceeds to the processing of image data for the fifth CIS 204. In S611, the values ​​referenced in the processes of S603 and S604 for determining whether a pixel is valid or invalid and the value for determining whether a pixel is in a combined region are updated to values ​​for the next CIS specified by the CPU 400, and the processing of image data for the next CIS is resumed from S600. When it is determined in S609 that the processing of image data for one line has been completed, the first buffer reading unit 511 terminates the series of processes. The processing by the second buffer reading unit 512 is also the same as that performed by the first buffer reading unit 511. Therefore, if the first buffer 506 in the description of FIG. 6 is replaced with the second buffer 507, the first counter 509 with the second counter 510, and the second counter 510 with the first counter 509, then the processing can be interpreted as being performed by the second buffer reader 512.

[0046] 7 is a diagram illustrating the flow of processing image data from the first buffer reading unit 511, the second buffer reading unit 512, and the mask data reading unit 513 by the internal merge processing unit 514 according to the embodiment. In FIG. 7, the horizontal axis represents the time axis, with time progressing from left to right. In parallel with this, the image processing by each reading unit is shown progressing one pixel at a time. Each square represents image data (pixel data) for one pixel.

[0047] First, the first buffer reading unit 511 starts processing from the image data of the first CIS 200, and the second buffer reading unit 512 starts processing from the image data of the second CIS 201. Since only the image data of the first CIS 200 is valid up to the first combined region, only the pixel data read by the first buffer reading unit 511 is passed as valid image data to the internal combined processing unit 514. At this time, the internal combined processing unit 514 passes the image data of the first CIS 200 as is to the downstream DMAC output unit 515.

[0048] In parallel with this processing, the second buffer reading unit 512 processes the image data of the second CIS 201. Because the leftmost invalid pixel of the second CIS 201 is image data of an invalid pixel that does not pass image data to the internal merge processing unit 514, the second buffer reading unit 512 discards the pixel data read from the second buffer 507. After discarding the image data of all pixels in the leftmost invalid pixel region, the second buffer reading unit 512 thus enters a standby state until the image data processing by the first buffer reading unit 511 reaches the merged region.

[0049] In this way, the first buffer reading unit 511 completes processing of the image data of the first CIS 200 up to the first combined region, and then moves on to processing the image data corresponding to the first combined region. Here, the first buffer reading unit 511, the second buffer reading unit 512, and the mask data reading unit 513 simultaneously pass the image data of the first CIS 200, the image data of the second CIS 201, and the mask data to the internal combining processing unit 514. The internal combining processing unit 514 generates a single image data by combining the image data of the first CIS 200 and the second CIS 201 based on the value of the mask data. Similar processing is performed on the other pixels in the first combined region.

[0050] When the processing of the first combined region is completed in this manner, only the image data read by the second buffer reading unit 512 is passed as valid data to the internal combined processing unit 514. The internal combined processing unit 514 passes the image data of the second CIS 201 as is to the downstream DMAC output unit 515.

[0051] In parallel with the image processing performed by the second buffer reader 512, the first buffer reader 511 processes pixel data corresponding to the right-end invalid pixel region of the first CIS 200. The right-end invalid pixel region of the first CIS 200 contains pixel data of invalid pixels that are not passed to the internal merge processor 514. Therefore, after reading the pixel data from the first buffer 506, the first buffer reader 511 discards the read pixel data. When the processing of the right-end invalid pixel region of the first CIS 200 is completed in this manner, the processing of image data for all pixels of the first CIS 200 is completed. After this, the first buffer reader 511 proceeds to processing the image data of the third CIS 202.

[0052] The first buffer reading unit 511 processes pixel data corresponding to the leftmost invalid pixel region of the third CIS 202 in parallel with the processing of image data by the second buffer reading unit 512. The processing of pixel data of invalid pixels is similar to the pixel data processing of invalid pixels in the first CIS 200. When the processing of pixel data corresponding to the leftmost invalid pixel region of the third CIS 202 is completed, the first buffer reading unit 511 enters a standby state until the second buffer reading unit 512 completes processing up to the next combined region. The processing thereafter is similar to the processing from the first combined region onwards, and will not be described further.

[0053] The series of processes up to this point is performed for each of the constituent CISs to complete the merging process for one line of image data. While Fig. 7 shows the processing time per pixel in the first merged region as being extended, this is merely to make it easier to understand visually. Therefore, the internal merger 514 can perform the merging process for the image data in the first merged region in the same processing time as when the image data of the first CIS 200 and the image data of the second CIS 201 are output as is.

[0054] FIG. 8 is a diagram showing an example of the combination gravity ratio in the combined region of the first CIS 200 and the second CIS 201 in the image data combination process in the internal combination processor 514 according to the embodiment.

[0055] The mask data represents the combination weight ratio of the two image data to be combined. In this embodiment, the mask data is represented by 4 bits (maximum value 15). In relation to the combination weight ratio shown in FIG. 8, since the maximum value of the mask data is "15", a value of "15" represents a combination weight ratio of 100%. If the image data of the first CIS 200 to be combined is D1, the image data of the second CIS 201 is D2, the mask data is Md, and the maximum value of the mask data is Md.max, the image data S after the combining process is expressed by the following formula (1).

[0056] S=(D1×(Md.max-Md))+D2×Md) / Md.max…Formula (1) 8(a), when the image data of the first CIS 200 is output as is as the output result of the internal join processor 514, the join processing is performed in the internal join processor 514 with the join weight ratio of the first CIS 200 set to 100%. In this case, since the output data is the image data of the first CIS 200 itself, it is possible to use a method of outputting the image data of the first CIS 200 as is without applying formula (1) for calculation.

[0057] The process in the merging region that merges the image data of the first CIS 200 and the second CIS 201 is performed by gradually decreasing the merge weight of the first CIS 200 and gradually increasing the merge weight of the second CIS 201 as the merging process in the merging region progresses. That is, the proportion of image data from the first CIS 200 increases the closer to the first CIS 200, and decreases the farther away from the first CIS 200. Conversely, the proportion of image data from the second CIS 201 increases the closer to the second CIS 201. Finally, the image data from the second CIS 201 is output as is as the output result of the internal merging processor 514. In this case, the merging process in the internal merging processor 514 is performed with the merge weight of the second CIS 201 set to 100%. Expressing this in equation (1), the value of the mask data Md starts at 0, and as the combining process in the combined area section progresses, the value of the mask data Md gradually increases, and when the image data of the second CIS 201 is finally output as the output result of the internal combining processing section 514 as is, the value of the mask data Md becomes "15".

[0058] In this example, the binding gravity is changed linearly as a general concept, but mask data obtained by other methods such as random generation or polynomial functions may also be used. Also, the bit width of the mask data is not limited to 4 bits as described in this example.

[0059] FIG. 8B is a diagram showing an example of the arrangement of mask data stored in the mask memory 500 according to the embodiment.

[0060] 8(b) shows an example of a mask memory area where the combined area width is a maximum of 64 pixels, and where each combined area can store up to 64 lines of mask data. In this embodiment, since there are five CISs, four combined areas are assumed.

[0061] The mask memory 500 stores 4-bit mask data per pixel as described with reference to Fig. 8(a). The mask memory read control unit 505 reads out mask data for the first combined region, starting with the first pixel on the first line of the first combined region mask data 800, in order to read out the second pixel, third pixel, and so on. In this example, a combined region with a maximum width of 64 pixels is assumed, but if the combined region is composed of only 32 pixels, for example, it is possible to stop reading the mask data for the 32nd pixel without reading up to the 64th pixel shown in Fig. 8(b).

[0062] When the combining process for the first combined region is completed, the mask memory read control unit 505 reads mask data from the first pixel of the first line of the second combined region mask data 801. When the combining process for the first line of the second combined region is completed, the combining process is continued in sequence, with the combining process for the first line of the third combined region mask data 802. Finally, the combining process for the first line of the fourth combined region mask data 803 is completed.

[0063] In the embodiment, a scanner having five CISs is used as an example, so processing is performed up to the fourth combined area mask data, but in the case of a scanner consisting of, for example, three CISs, it is sufficient to perform combining processing up to the second combined area mask data.

[0064] When the merging process for the first line is completed and a processing start signal is sent from the operation instruction unit 414 to the internal merging process unit 514, the merging process for the second line begins. In the merging process for the second line, the merged area mask data for the second line is applied to each merged area. Except for using the mask data for the second line, the merging process for the second line is the same as the merging process for the first line.

[0065] Processing the lines to be joined in this manner in order will require processing of 64 lines and more stored in mask memory 500. When joining processing of the 64th line is completed and processing of the 65th line is to be performed, the mask data of the first line is read from mask memory 500 as the mask data to be applied to the 65th line. When processing the 66th line, the mask data of the next line, the second line, is read from mask memory 500 as the mask data to be applied to the 66th line. Therefore, when processing the line following the last line number in mask memory 500, which in this embodiment is the 64th line, the mask data is read from the position of the first line in mask memory 500.

[0066] In the embodiment, the data size of the mask memory 500 is set to a maximum width of 64 pixels and a maximum number of lines of 64 for one combined area. However, this is not limited to these values, and the mask memory may be allocated with values ​​that match the specifications of the image reading device at that time. For example, if the combined area is at most 32 pixels wide, a mask memory with a maximum width of 32 pixels can reduce the circuit size required for the mask memory 500 compared to the maximum width of 64 pixels described in the embodiment. Alternatively, if image unevenness in the combined area caused by a small number of lines of mask data can be tolerated to a certain extent, the maximum number of lines of the mask memory 500 can be reduced. For example, by setting the maximum number of lines to 32, the circuit size required for the mask memory 500 can be reduced compared to the maximum number of lines of 64 lines in the embodiment. On the other hand, if image unevenness cannot be tolerated with a maximum number of lines of 64, increasing the maximum number of lines increases the circuit size, but is expected to reduce image unevenness.

[0067] FIG. 9 is a perspective view showing the appearance of an image forming apparatus according to an embodiment, which has a function of reading images of, for example, A0 size or B0 size.

[0068] An example of an image forming apparatus having an image reading function will be described with reference to FIG. 9. A reading device stand 901 is provided on a recording device 900, and an image reading device 902 is held by the reading device stand 901. The recording device 900 and the image reading device 902 are connected by an inter-device connection cable 903, which is used for transmitting image data read by the image reading device 902 to the recording device 900, transmitting and receiving sensor signals, and transmitting and receiving operation instruction signals from the recording device 900 to the image reading device 902. The image reading device 902 is a large-format scanner having multiple CISs. The image reading device 902 has a configuration similar to that shown in FIG. 2. Even in such an image forming apparatus having an image reading function, the configuration and image processing method for performing the combining process described above may be adopted.

[0069] In this embodiment, an image reading device configured with CISs arranged in a staggered pattern has been described as an example.

[0070] FIG. 10 is a diagram showing an example of an arrangement of CISs according to another embodiment.

[0071] For example, the present invention can be applied to cases where the CISs 200-204 are arranged in a stepped pattern as shown in Figure 10(a) or in a convex pattern as shown in Figure 10(b). Therefore, the arrangement is not limited to the staggered arrangement shown in the embodiment, as long as the ends of the multiple CISs in the main scanning direction overlap when viewed from the sub-scanning direction. Furthermore, the number of CISs is not limited to the number described in this embodiment.

[0072] As described above, according to the embodiment, when image processing in a combined area involves reading image data that has been read by multiple image sensors and stored in memory, it is possible to read the image data from the multiple image sensors simultaneously from the memory.

[0073] Furthermore, since the image data of the combined area of ​​the image data of the multiple image sensors read from the memory can be stored in parallel in a buffer, the buffer can be smaller in size. Therefore, unlike conventional technology, there is no need to prepare a large buffer that temporarily stores image data of the entire combined area. This allows for a reduction in circuit size.

[0074] Furthermore, in the combined area, image data from two image sensors can be processed simultaneously, increasing processing speed.

[0075] (Other embodiments) The present invention can also be realized by supplying a program that realizes one or more functions of the above-described embodiments to a system or device via a network or a storage medium, and having one or more processors in the computer of the system or device read and execute the program. It can also be realized by a circuit (e.g., ASIC) that realizes one or more functions.

[0076] The present invention is not limited to the above-described embodiments, and various modifications and variations can be made without departing from the spirit and scope of the present invention. Therefore, the following claims are appended to apprise the public of the scope of the present invention. [Explanation of symbols]

[0077] 100...scanner, 105...original detection sensor, 106...line image sensor (CIS), 112...edge detection sensor, 301...system ASIC, 306...A / D conversion unit, 400...CPU, 406...integration processing unit, 409...external memory, 410...scanned image buffer, 414...operation instruction unit, 500...mask memory, 509...first counter, 510...second counter, 514...internal connection processing unit

Claims

1. a plurality of line image sensors arranged to have overlapping regions in which the reading regions of adjacent image sensors partially overlap in a main scanning direction in which the document is read; a storage means for storing image data obtained by reading predetermined lines of the document by the plurality of line image sensors; a first readout means for reading out image data obtained by reading with a first line image sensor among the plurality of line image sensors from the storage means; a second reading means for reading, from the storage means, image data obtained by reading with a second line image sensor adjacent to the first line image sensor in the main scanning direction; a discrimination means for discriminating image data corresponding to a plurality of overlapping areas from the read image data; a combining means for combining first image data and second image data obtained by the first line image sensor and the second line image sensor, respectively, corresponding to each of the plurality of overlapping regions determined by the determining means, to generate image data for each of the plurality of overlapping regions; a generating means for generating image data of the predetermined line of the document based on image data obtained by excluding image data of the plurality of overlapping regions from the image data stored in the storing means and the image data of each of the plurality of overlapping regions generated by the combining means; a control means for controlling the storage means, the determination means, the synthesis means, and the generation means to repeatedly execute processes for a predetermined line of the document in a sub-scanning direction of the document; An image reading device comprising:

2. 2. The image reading device according to claim 1, further comprising a counting means for counting the number of pixels of the image data read from the storage means, and the discrimination means for discriminating each of the plurality of overlapping areas based on the count value counted by the counting means.

3. When the plurality of line image sensors include an invalid pixel area on the assumption that the acquired image data is to be discarded, the combining means combines the first image data and the second image data excluding the image data corresponding to the invalid pixel area, 3. The image reading device according to claim 1, wherein the generating means further generates image data of the predetermined line of the document by excluding image data corresponding to the invalid pixel area from the image data stored in the storage means.

4. The image processing device further includes a storage unit for storing ratio data for combining the first image data corresponding to the overlapping region and the second image data corresponding to the overlapping region, 4. The image reading apparatus according to claim 1, wherein the combining means combines the first image data and the second image data based on the ratio data supplied from the storage means.

5. An image reading device as described in claim 4, characterized in that the ratio data increases the proportion of the first image data in the overlapping area closer to the first line image sensor and increases the proportion of the second image data closer to the second line image sensor.

6. a plurality of line image sensors arranged to have overlapping regions in which the reading regions of adjacent image sensors partially overlap in a main scanning direction in which the document is read; a first storage means for storing image data obtained by a first line image sensor, which reads the document first among the plurality of line image sensors, reading an image of a predetermined line of the document; a second storage means for storing image data obtained by a second line image sensor, which is one of the plurality of line image sensors and follows the first line image sensor, reading an image of the predetermined line of the document; a combining means for combining first image data corresponding to the overlapping region among the image data stored in the first storage means and second image data corresponding to the overlapping region among the image data stored in the second storage means to generate image data of the overlapping region; a generating means for generating image data of the predetermined line corresponding to the first line image sensor and the second line image sensor based on image data stored in the first storage means excluding image data of the overlapping region, image data stored in the second storage means excluding image data of the overlapping region, and image data generated by the combining means; a control unit that controls the first storage unit, the second storage unit, the combining unit, and the generating unit so that the processes are executed across the sub-scanning direction of the document; The image reading device according to claim 1, wherein the first storage means and the second storage means are buffers configured to store a number of pixels that is less than the number of pixels corresponding to the maximum width of the overlapping area.

7. 7. The image reading device according to claim 6, wherein the plurality of line image sensors are arranged in a staggered pattern in two rows in the main scanning direction.

8. further comprising counting means for counting the number of pixels of the image data read out from each of the first storage means and the second storage means; The image reading device according to claim 6 or 7, characterized in that the combining means determines whether the image data corresponds to the first image data or the second image data corresponding to the overlapping area based on the count value counted by the counting means.

9. An image reading device according to any one of claims 6 to 8, characterized in that when at least one of the first line image sensor and the second line image sensor includes an invalid pixel area for which the acquired image data is to be discarded, the image data corresponding to the invalid pixel area is not supplied to the combining means.

10. The image processing device further includes a storage unit for storing ratio data for combining the first image data corresponding to the overlapping region and the second image data corresponding to the overlapping region, 10. The image reading apparatus according to claim 6, wherein the combining means combines the first image data and the second image data based on the ratio data supplied from the storage means.

11. The image reading device according to claim 10, characterized in that the ratio data increases the proportion of the first image data in the overlapping area closer to the first line image sensor, and increases the proportion of the second image data in the overlapping area closer to the second line image sensor.

12. A method for controlling an image reading device having a plurality of line image sensors arranged to have overlapping areas in which the reading areas of adjacent image sensors partially overlap in a main scanning direction in which a document is read, comprising: a storing step of storing image data obtained by reading predetermined lines of the document by the plurality of line image sensors in a memory; a first reading step of reading image data obtained by reading with a first line image sensor among the plurality of line image sensors from the memory; a second reading step of reading from the memory image data obtained by reading with a second line image sensor adjacent to the first line image sensor in the main scanning direction; a determining step of determining image data corresponding to a plurality of overlapping regions from the read image data; a combining step of combining first image data and second image data obtained by the first line image sensor and the second line image sensor, respectively, corresponding to each of the plurality of overlapping regions determined in the determining step to generate image data for each of the plurality of overlapping regions; a generating step of generating image data of the predetermined line of the document based on image data obtained by excluding image data of the plurality of overlapping regions from the image data stored in the storing step and the image data of each of the plurality of overlapping regions generated in the combining step; a control step of controlling the storing step, the determining step, the combining step, and the generating step to be repeatedly executed for a predetermined line of the document in a sub-scanning direction of the document; A control method comprising:

13. A method for controlling an image reading device having a plurality of line image sensors arranged to have overlapping areas in which the reading areas of adjacent image sensors partially overlap in a main scanning direction in which a document is read, comprising: a first storing step of storing image data obtained by a first line image sensor, which reads the document first among the plurality of line image sensors, reading an image of a predetermined line of the document; a second storage step of storing image data obtained by a second line image sensor, which is one of the plurality of line image sensors and follows the first line image sensor, reading an image of the predetermined line of the document; a combining step of combining first image data corresponding to the overlapping region among the image data stored in the first storing step and second image data corresponding to the overlapping region among the image data stored in the second storing step to generate image data of the overlapping region; a generating step of generating image data of the predetermined line corresponding to the first line image sensor and the second line image sensor based on the image data stored in the first storing step excluding the image data of the overlapping region, the image data stored in the second storing step excluding the image data of the overlapping region, and the image data generated in the combining step; a control step of controlling the first storing step, the second storing step, the combining step, and the generating step to be executed across the sub-scanning direction of the document; A control method characterized in that the first storage step and the second storage step store the image data in a buffer configured to store a number of pixels less than the number of pixels corresponding to the maximum width of the overlapping area.

14. A program for causing a computer to execute each step of the control method according to claim 12 or 13.

Images