JP2013153357A - Image reading device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance utilization efficiency of a memory including a work memory used for transfer of image data between data processing units in an image reading device.SOLUTION: A primary page memory area 15 in a poststage of a work memory area 13 is used as part of a plurality of buffer areas of the work memory area 13, and when a writing position of image data in the primary page memory area 15 has reached a predetermined position 31, a main control unit reduces the number of buffer areas 15a, 15b of the work memory area 13 allocated within the primary page memory area 15.

Description

  The present invention relates to an image reading apparatus.

  The image reading device optically reads a page image, generates image data of the page image, and performs predetermined processing on the image data. Image data is temporarily stored in a predetermined page memory area in the middle of processing, in the preceding stage, or in the subsequent stage.

  In order to improve the memory utilization efficiency, a certain image reading apparatus predicts a surplus in the page memory from the compression rate of the image data and releases the surplus (see, for example, Patent Document 1).

JP 2009-225246 A

  In an image reading apparatus, usually, a plurality of data processing units sequentially process image data. When pipeline processing is performed by a plurality of data processing units, image data is transferred between the data processing units via a work memory. Usually, a work memory used for transferring image data between data processing units is secured separately from a page memory.

  In the technique of the above-mentioned patent document 1, since the work memory is not considered, the utilization efficiency of the memory including the work memory used for the transfer of the image data between the data processing units is not optimal.

  The present invention has been made in view of the above problems, and an object of the present invention is to obtain an image reading apparatus in which the use efficiency of a memory including a work memory used for transferring image data between data processing units is increased. And

  In order to solve the above problems, the present invention is configured as follows.

  An image reading apparatus according to the present invention includes a scanner unit that generates and outputs image data by image reading, a plurality of data processing units, a work memory region having a plurality of buffer regions, and a page memory region subsequent to the work memory region. And a control unit that reduces the number of buffer areas of the work memory area allocated in the page memory area when the image data writing position in the page memory area reaches a predetermined position. Prepare. The plurality of buffer areas include image data output by the scanner unit, or image data obtained by performing predetermined processing on the image data output by the scanner unit, of two of the plurality of data processing units for each band. It is used repeatedly in order when passing between two data processing units. The page memory area is used as a part of a plurality of buffer areas while image data after processing is written by a predetermined data processing section among the plurality of data processing sections.

  As a result, a part of the page memory area is shared as a part of the work memory area, so that the total size of the memory area secured as the page memory area and the work memory area can be reduced, and the page memory area is written to the page memory area. Since the size of the work memory area adaptively changes according to the size of the image data, the work memory area can be increased when the size of the image data written in the page memory area is small.

  Therefore, the use efficiency of the memory including the work memory used for the transfer of the image data between the data processing units is increased.

  In addition to the above image reading apparatus, the image reading apparatus according to the present invention may be as follows. In this case, the buffer area of the work memory area allocated in the page memory area is located at the end of the page memory area.

  This reduces the number of buffer areas of the work memory area allocated in the page memory area.

  The image reading apparatus according to the present invention may be as follows in addition to any of the image reading apparatuses described above. In this case, when the writing position of the image data in the page memory area reaches a predetermined position, the control unit sets the number of buffer areas in the work memory area allocated in the page memory area to zero.

  As a result, when the image data written in the page memory area is large, the entire page memory area can be used. Therefore, even if the image data size is large, a memory full error in the page memory area is unlikely to occur.

  The image reading apparatus according to the present invention may be as follows in addition to any of the image reading apparatuses described above. In this case, the work memory area is used as an input buffer for a predetermined data processing unit.

  The image reading apparatus according to the present invention may be as follows in addition to any of the image reading apparatuses described above. In this case, the predetermined data processing unit described above performs compression processing, and writes the compressed image data in the page memory area.

  This increases the number of buffer areas in the work memory area when the compression ratio of the image data is good, and increases the number of buffer areas in the work memory area when the compression ratio of the image data is not good. The size of the work memory area and the page memory area can be adapted to the compression rate of the image data.

  According to the present invention, in the image reading apparatus, the use efficiency of the memory including the work memory used for the transfer of the image data between the data processing units is increased.

FIG. 1 is a block diagram showing a configuration of an image reading apparatus according to an embodiment of the present invention. FIG. 2 is a block diagram for explaining various memory areas and data flow in the image reading apparatus shown in FIG. FIG. 3 is a diagram showing an example of the work memory area in FIG. FIG. 4 is a flowchart for explaining compression processing in the image reading apparatus shown in FIG. FIG. 5 is a diagram illustrating a process of reducing the buffer area in the primary page memory area when the compression rate is low in the image reading apparatus shown in FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram showing a configuration of an image reading apparatus according to an embodiment of the present invention. The image reading apparatus shown in FIG. 1 includes a scanner unit 1, an image processing unit 2, a memory 3, a main control unit 4, and an output unit 5, which are connected to one another.

  The scanner unit 1 optically reads a page image of a document, generates image data of the page image, and outputs it.

  The image processing unit 2 performs predetermined processing on the image data. The image processing unit 2 performs predetermined processing on the image data output from the scanner unit 1 or image data obtained by performing the previous processing on the image data output by the scanner unit 1. The image processing unit 2 writes the image data after the predetermined processing into a predetermined memory area in the memory 3. For example, the image processing unit 2 includes one or a plurality of ASICs (Application Specific Integrated Circuits).

  The memory 3 is a volatile memory such as a DRAM (Dynamic Random Access Memory). In the memory 3, a memory area required for processing by the image processing unit 2 is appropriately secured.

  FIG. 2 is a block diagram for explaining various memory areas and data flow in the image reading apparatus shown in FIG.

  In FIG. 2, a CCD (Charge Coupled Device) 11 is an image sensor that outputs an optically obtained page image as an electrical signal. The reading ASIC 12 is a circuit that converts an electrical signal from the CCD 11 into image data and outputs the image data. The CCD 11 and the reading ASIC 12 are included in the scanner unit 1.

  The work memory area 13 is secured in the memory 3 and is used as an output buffer for the read ASIC 12 and an input buffer for the codec ASIC 14.

  The codec ASICs 14 and 20 are circuits that compress image data. The codec ASICs 14 and 20 compress image data by a compression method such as JPEG (Joint Photographic Experts Group).

  The primary page memory area 15 is secured in the memory 3 and stores image data (compressed image data) converted by the reading ASIC 12, that is, image data before being processed by the image processing ASIC 18 (compressed image data). This is a memory area for That is, the primary page memory area 15 is an area downstream (downstream) from the work memory area 13 and is an area in which the codec ASIC 14 writes processed image data.

  The size of the primary page memory area 15 is a value obtained by multiplying the size of the image data (uncompressed RAW data) for one page by the minimum compression rate (for example, 35%) of the ASIC 14 for codec. Note that the compression rate is several percent in the case of image data of a normal text document, and the compression rate is several percent to 20 percent in the case of image data of a normal photo document.

  The codec ASIC 16 is a circuit that decompresses the compressed image data by a decompression method corresponding to the compression method of the codec ASIC 14.

  The work memory area 17 is secured in the memory 3 and is used as an output buffer of the codec ASIC 16 and an input buffer of the image processing ASIC 18.

  The image processing ASIC 18 is a circuit that performs predetermined image processing (resolution conversion, rotation, data format conversion, etc.) on the image data.

  The work memory area 19 is secured in the memory 3 and is used as an output buffer for the image processing ASIC 18 and an input buffer for the codec ASIC 20.

  The secondary page memory area 21 is secured in the memory 3 and is a memory area for storing image data (compressed image data) after image processing by the image processing ASIC 18. That is, the secondary page memory area 21 is an area downstream (downstream) from the work memory area 19 and is an area in which the codec ASIC 20 writes processed image data.

  The codec ASICs 14, 16, and 20 and the image processing ASIC 18 are included in the image processing unit 2.

  As shown in FIG. 2, the image data output from the reading ASIC 12 is transferred to the codec ASIC 14 via the work memory area 13, and the image data compressed by the codec ASIC 14 is one band (a predetermined number of lines). They are stored in the primary page memory area 15 one by one. The codec ASIC 16 sequentially reads and expands the compressed image data stored in the primary page memory area 15 and passes the expanded image data to the image processing ASIC 18 via the work memory area 17. The image data subjected to the image processing by the image processing ASIC 18 is transferred to the codec ASIC 20 via the work memory area 19, and the image data compressed by the codec ASIC 20 is sequentially stored in the secondary page memory area 21. To go.

  FIG. 3 is a diagram showing an example of the work memory area 13 in FIG.

  As shown in FIG. 3, the work memory area 13 has two buffer areas 15 a and 15 b in the primary page memory area 15 and one buffer area 13 a outside the primary page memory area 15 in the initial state. The buffer area outside the primary page memory area 15 is a minimum memory area necessary for transfer between the ASICs 12 and 14. If the writing position of the image data written in the primary page memory area 15 has not reached the predetermined position 31, the buffer areas 15a, 15b, 13a in the work memory area 13 transfer the image data output from the scanner unit 1 to the ASIC 12 , 14 are used repeatedly in order. When the writing position of the image data written in the primary page memory area 15 reaches the predetermined position 31, the buffer areas 15a and 15b are used as the original primary page memory area 15, and the buffer area 13a of the work memory area 13 is used. However, it is repeatedly used when the image data output by the scanner unit 1 is transferred between the ASICs 12 and 14.

  For example, the predetermined position 31 is a position that is the size of one band of image data (image data before compression) from the head of the buffer area 15a.

  The plurality of buffer areas 15a, 15b, 13a in the work memory area 13 are used as double buffers or ring buffers. In the case shown in FIG. 3, a plurality of buffer areas in the work memory area 13 are used as ring buffers.

  Accordingly, in the plurality of buffer areas 15a, 15b, and 13a, data is written in order from the first buffer area 15a to the last buffer area 13a, and data is written to the first buffer area 15a next to the last buffer area 13a. . One buffer area has a size capable of storing image data for one band (image data that is not compressed and has a fixed size).

  The buffer areas 15a and 15b in the primary page memory area 15 are located at the end of the primary page memory area 15, and the buffer areas 15a and 15b and the buffer area 13a outside the primary page memory area 15 are continuous. .

  The work memory area 19 is the same as the work memory area 13.

  Returning to FIG. 1, the main control unit 4 controls the scanner unit 1, the image processing unit 2, the memory 3, and the output unit 5. In addition, the main control unit 4 secures memory areas (work memory areas 13, 17, 19, primary page memory area 15, secondary page memory area 21 and the like) required for the image processing unit 2 in the memory 3. The output unit 5 outputs the image data after the image processing by the image processing unit 2.

  Further, when the writing position of the image data in the primary page memory area 15 reaches the predetermined position 31, the main control unit 4 buffers the buffer area 15a of the work memory area 13 allocated in the primary page memory area 15. , 15b is reduced.

  In this embodiment, when the writing position of the image data in the primary page memory area 15 reaches a predetermined position 31, the main control unit 4 works the work memory area 13 allocated in the primary page memory area 15. Set the number of buffer areas to zero. That is, when the size of the image data written in the primary page memory area 15 is large, the image data is transferred between the ASICs 12 and 14 only in the buffer area 13a outside the primary page memory area 15.

  The main control unit 4 similarly controls the secondary page memory area 21 and the work memory area 19.

  Next, operations of the image reading apparatus (mainly the image processing unit 2 and the main control unit 4) will be described.

  Here, compression processing by the codec ASIC 14 and writing of compressed image data to the primary page memory area 15 will be described. FIG. 4 is a flowchart for explaining compression processing in the image reading apparatus shown in FIG. FIG. 5 is a diagram illustrating a process of reducing the buffer area in the primary page memory area 15 when the compression rate is low in the image reading apparatus shown in FIG.

  The main control unit 4 secures the primary page memory area 15, sets its address information (start address and size, or start address and end address) in the codec ASICs 14 and 16, and, as shown in FIG. A work memory area 13 is secured by continuously and partially overlapping the primary page memory area 15, and address information (start address and size, or start address and end address) of the work memory area 13 is read for the ASIC 12 and codec Set to ASIC14.

  In the case of FIG. 3, in the initial state, the reading ASIC 12 uses the three buffer areas 15a, 15b, 13a in the work memory area 13 as output buffers in order, and the codec ASIC 14 uses the buffer areas 15a, 15b, 13a. Are used as input buffers in order. That is, the reading ASIC 12 writes the image data for one band in the buffer area 15a, then writes the image data of the next band in the buffer area 15b, and writes the image data of the next band in the buffer area 13a. Then, the reading ASIC 12 writes the image data of the next band in the buffer area 15a. On the other hand, the codec ASIC 14 reads the image data for one band from the buffer area 15a, reads the image data of the next band from the buffer area 15b, and reads the image data of the next band from the buffer area 13a. Then, the codec ASIC 14 reads the image data of the next band from the buffer area 15a. Thus, in the initial state, the work memory area 13 has the three buffer areas 15a, 15b, and 13a, and is used as a ring buffer by the reading ASIC 12 and the codec ASIC 14.

  Next, compression processing by the codec ASIC 14 will be described.

  The codec ASIC 14 reads the image data for one band from the work memory area 13 and compresses it, and writes the compressed image data for one band in the primary page memory area 15 (step S1). The size of image data before compression for one band is constant, but the size of compressed image data for one band is not constant. The compressed image data of each band is continuously written in the compressed image data of the previous band without a gap. The head storage position and the end storage position (or size) of the compressed image data of each band are managed by the main control unit 4, and when the compressed image data of each band is read from the primary page memory area 15, the main control unit The read position of the compressed image data of each band is specified from the start storage position and the end storage position (or size) managed by 4.

  The codec ASIC 14 monitors whether or not the writing position of the image data has reached a predetermined position 31 (that is, a predetermined address) in the primary page memory area 15 (step S2).

  When the writing of the compressed image data for one band is completed, the codec ASIC 14 determines whether or not the processing for the band for one page is completed (step S3), and the processing for the band for one page is completed. If not, the process returns to step S1 and the next band is similarly processed.

  When the compression rate of the image data is high, as shown in FIG. 5A, the writing position does not reach the predetermined position 31, and the compressed image data for one page to the primary page memory area 15 is stored. Writing is complete.

  On the other hand, when the compression rate of the image data is low, as shown in FIG. 5B, the writing position is set before the writing of the compressed image data for one page to the primary page memory area 15 is completed. The predetermined position 31 is reached.

  When the codec ASIC 14 detects that the image data writing position has reached the predetermined position 31, the main control unit 4 terminates the use of the buffer areas 15 a and 15 b in the primary page memory area 15, and reads the ASIC 12. Then, the codec ASIC 14 is controlled, and thereafter, only the buffer area 13a is used as the work memory area 13 between the read ASIC 12 and the codec ASIC 14 to transfer image data (step S4).

  At this time, the reading ASIC 12 does not write image data in the buffer areas 15a and 15b, but writes image data in the buffer area 13a, and the codec ASIC 14 follows the command from the main control section 4, and the codec ASIC 14 When the instruction is received, image data that has not been read out is sequentially read out, and then the image data is read out only from the buffer area 13a.

  In this state, the reading ASIC 12 uses one buffer area 13a in the work memory area 13 as an output buffer, and the codec ASIC 14 uses the buffer area 13a as an input buffer.

  The codec ASIC 14 continues to write image data regardless of the writing position, and continuously writes the compressed image data to the primary page memory area 15.

  Thereafter, the codec ASIC 14 similarly reads and compresses the subsequent image data for one band from the work memory area 13 and writes the compressed image data for one band in the primary page memory area 15 (step S5). ). When the writing of the compressed image data for one band is completed, the ASIC for codec 14 determines whether or not the processing for the band for one page is completed (step S6), and the processing for the band for one page is completed. If not, the process returns to step S5 and the next band is similarly processed. In this manner, compression processing and writing of compressed image data are sequentially executed up to the last band of one page. In this case, since the buffer areas 15a and 15b allocated in the primary page memory area 15 in the initial state are not used as the work memory area 13, the image data before compression is overwritten with the image data compressed in the buffer areas 15a and 15b. Will not occur.

  As described above, according to the above embodiment, the primary page memory area 15 subsequent to the work memory area 13 is used as a part of the plurality of buffer areas of the work memory area 13, and the main control unit 4 When the image data writing position in the page memory area 15 reaches a predetermined position 31, the number of buffer areas of the work memory area 13 allocated in the primary page memory area 15 is reduced.

  Thereby, since a part of the primary page memory area 15 is shared as a part of the work memory area 13, the total size of the memory areas secured as the primary page memory area 15 and the work memory area 13 can be reduced. Since the size of the work memory area 13 is adaptively changed according to the size of the image data written in the primary page memory area 15, when the size of the image data written in the primary page memory area 15 is small, the work memory area 13 is The image data is transferred from the reading ASIC 12 to the codec ASIC 14 efficiently.

  Therefore, the utilization efficiency of the memory 3 including the work memory area 13 used for transferring image data between the ASICs 12 and 14 is increased.

  The above-described embodiments are preferred examples of the present invention, but the present invention is not limited to these, and various modifications and changes can be made without departing from the scope of the present invention. is there.

  For example, in the above-described embodiment, the preceding process of the page memory areas 15 and 21 is the compression process, but may be another type of process.

  The present invention can be applied to, for example, a scanner, a copying machine, and a multifunction machine having an image reading function.

1 Scanner unit 3 Memory 4 Main control unit (an example of control unit)
12 ASIC for reading (part of an example of multiple data processing units)
13 Work memory area 13a, 15a, 15b Buffer area 14 ASIC for codec (a part of an example of a plurality of data processing units, an example of a predetermined data processing unit)
15 Primary page memory area (example of page memory area)

Claims (5)

A scanner unit that generates and outputs image data by image reading;
A plurality of data processing units;
Two data processing units out of the plurality of data processing units for each band of image data output by the scanner unit or image data obtained by performing predetermined processing on the image data output by the scanner unit A work memory area having a plurality of buffer areas that are repeatedly used in order when passing between them, and an image that has been processed by a predetermined data processing section of the plurality of data processing sections after the work memory area A memory in which a page memory area is reserved as data is written and used as part of the plurality of buffer areas;
A controller that reduces the number of buffer areas of the work memory area allocated in the page memory area when the writing position of the image data in the page memory area reaches a predetermined position;
An image reading apparatus comprising:   The image reading apparatus according to claim 1, wherein the buffer area of the work memory area allocated in the page memory area is located at an end portion of the page memory area.   When the writing position of the image data in the page memory area reaches a predetermined position, the control unit sets the number of the buffer areas in the work memory area allocated in the page memory area to zero. The image reading apparatus according to claim 1, wherein the image reading apparatus is an image reading apparatus.   4. The image reading apparatus according to claim 1, wherein the work memory area is used as an input buffer of the predetermined data processing unit. 5.   5. The image according to claim 1, wherein the predetermined data processing unit performs a compression process and writes the image data after the compression process in the page memory area. 6. Reader.

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