JP5705143B2 - Image reading device - Google Patents

Description

  The present invention relates to an image reading apparatus.

  In the image reading apparatus, image data including image information of each pixel such as an RGB value, for example, and attribute data including attribute information of each pixel such as whether or not belonging to a character area are generated (for example, Patent Documents 1 to 3). 4).

  In an image processing apparatus, a memory area is set in advance for each of image data and attribute data, and the compressed image data and the compressed attribute data are stored in the memory area (see, for example, Patent Documents 1 and 2). ).

  In addition, when storing image data and attribute data after compression, a certain image processing apparatus stores compressed image data and compressed attribute data continuously for each line (see, for example, Patent Document 3).

JP 2007-281823 A JP 2007-286750 A JP 2005-244748 A Japanese Patent Laid-Open No. 2007-074412

  In the techniques of Patent Documents 1 and 2, since the compression rate of image data and attribute data varies depending on the data content, the size of the memory area described above is a size that allows image data and attribute data to be stored even when the compression rate is the lowest. It is said. Therefore, an unused portion corresponding to the actual compression rate is generated in the memory area.

  As in the technique of Patent Document 3, when image data and attribute data are continuously stored for each band in the page memory, the size of the compressed image data for one band is unknown until the compression is completed. Until the compression and writing of the image data is completed, the compression and writing of the attribute data cannot be started, and a delay occurs as shown in FIG.

  The technique described in Patent Document 4 is for fixed-length image data and attribute data, not for image data and attribute data whose size varies due to compression.

  The present invention has been made in view of the above-described problems, and provides an image reading apparatus that has high use efficiency of a page memory area and can reduce delay in writing of compressed image data and attribute data. With the goal.

  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 first buffer having a plurality of buffer areas for image data out of image data and attribute data generated by image reading, and a first buffer having a plurality of buffer areas for the attribute data. Two buffers, an image data compression unit that compresses the image data, and sequentially writes the compressed image data into a plurality of buffer areas of the first buffer, compresses the attribute data, and stores the compressed attribute data in the second An attribute data compressing unit for sequentially writing to a plurality of buffer areas of the buffer, compressed image data that has been written to any of the plurality of buffer areas of the first buffer, and a plurality of buffer areas of the second buffer Read the compressed attribute data that has been written to any of them and write it continuously to the page memory area. It includes a writing copy processing unit.

  As a result, the compressed image data and attribute data are temporarily stored in the first buffer and the second buffer, and continuously written in the page memory area. For this reason, the image data compression unit and the attribute data compression unit can operate in parallel without delay. Therefore, the use efficiency of the page memory area is increased, and the delay occurring in writing the compressed image data and attribute data can be shortened.

Also, images reading apparatus further comprises a compressed image data and compressed attribute data, the control unit that specifies the writing position to the page memory region. Then, the control unit is configured to compress the compressed image data stored in the plurality of buffer areas of the first buffer and / or compress the attribute data stored in the plurality of buffer areas of the second buffer. Based on the above, the writing position to the page memory area is specified. The page memory area is secured in a memory of a plurality of channels, and the copy processing unit writes the compressed image data and the compressed attribute data in the page memory area in parallel.

  Thereby, the compressed image data and the compressed attribute data can be written to the page memory area in parallel.

An image reading apparatus according to the present invention includes a first buffer having a plurality of buffer areas for image data out of image data and attribute data generated by image reading , and a first buffer having a plurality of buffer areas for the attribute data. Two buffers, an image data compression unit that compresses the image data, and sequentially writes the compressed image data into a plurality of buffer areas of the first buffer, compresses the attribute data, and stores the compressed attribute data in the second An attribute data compressing unit for sequentially writing to a plurality of buffer areas of the buffer, compressed image data that has been written to any of the plurality of buffer areas of the first buffer, and a plurality of buffer areas of the second buffer Read the compressed attribute data that has been written to any of them and write it continuously to the page memory area. It includes a writing copy processing unit. The copy processing unit then stores the size of the compressed image data stored in the plurality of buffer areas of the first buffer and / or the compressed attribute data stored in the plurality of buffer areas of the second buffer. Based on the size, the writing position to the page memory area is specified. Further, the page memory area is secured in a memory of a plurality of channels, and the copy processing unit writes the compressed image data and the compressed attribute data in the page memory area in parallel.

  Thereby, the compressed image data and the compressed attribute data can be written to the page memory area in parallel.

  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 image data and the attribute data are compressed for each band. Each of the plurality of buffer areas of the first buffer has a size capable of storing compressed image data for one band at the minimum compression ratio, and each of the plurality of buffer areas of the second buffer has a minimum compression ratio. 1 has a size capable of storing compressed attribute data for one band. The image data compression unit sequentially writes the compressed image data for each band to the plurality of buffer areas of the first buffer, and the attribute data compression unit stores the compressed attribute data for each band for the second buffer. Are sequentially written to the multiple buffer areas.

  According to the present invention, in the image reading apparatus, the use efficiency of the page memory area is increased, and the delay occurring in writing of the compressed image data and attribute data is shortened.

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 timing chart for explaining an example of operations of the codec ASIC and the copy processing circuit in FIG. FIG. 4 is a timing chart for explaining an example of a process for continuously writing compressed image data and attribute data.

  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, and generates and outputs image data and attribute data of the page image. The image data is data including image information of each pixel such as an RGB value, and the attribute data is data including attribute information of each pixel such as whether or not it belongs to a character area.

  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 or the like 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 generates and outputs image data and attribute data from the electrical signal from the CCD 11. 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 work memory area 13 has a plurality of buffer areas used as buffers for uncompressed image data (that is, RAW data), and functions as a double buffer or a ring buffer. Each buffer area has a size capable of storing image data (fixed length) for one band. One band is composed of a predetermined number of lines.

  The codec ASIC 14 is a circuit that compresses image data. The codec ASIC 14 compresses image data by a compression method such as JPEG (Joint Photographic Experts Group). The codec ASIC 14 compresses image data for each band.

  The work memory area 15 is secured in the memory 3 and is used as an output buffer of the codec ASIC 14 and an input buffer of the copy processing circuit 16. The work memory area 15 has a plurality (two in FIG. 2) of buffer areas 15a and 15b for storing compressed image data. The buffer areas 15a and 15b are used as double buffers. Note that the number of buffer areas may be three or more and used as a ring buffer. Each of the buffer areas 15a and 15b has a size capable of storing image data for one band compressed at the minimum compression rate.

  The codec ASIC 14 repeatedly writes the compressed image data to the plurality of buffer areas 15 a and 15 b in the work memory area 15 in order. That is, the codec ASIC 14 writes the compressed image data of a certain band to the buffer area 15a, writes the compressed image data of the next band to the buffer area 15b, and further stores the compressed image data of the next band. Write to the buffer area 15a.

  On the other hand, the work memory area 17 is secured in the memory 3 and used as an output buffer of the reading ASIC 12 and an input buffer of the codec ASIC 18. The work memory area 17 has a plurality of buffer areas used as buffers for uncompressed attribute data, and functions as a double buffer or a ring buffer. Each buffer area has a size capable of storing attribute data (fixed length) for one band. One band is composed of the same number of lines as one band of image data.

  The codec ASIC 18 is a circuit that compresses attribute data. The codec ASIC 18 compresses attribute data by a compression method such as a run length method. The codec ASIC 18 compresses attribute data for each band.

  The work memory area 19 is secured in the memory 3 and is used as an output buffer of the codec ASIC 18 and an input buffer of the copy processing circuit 16. The work memory area 19 has a plurality (two in FIG. 2) of buffer areas 19a and 19b for storing compressed attribute data. The buffer areas 19a and 19b are used as double buffers. Note that the number of buffer areas may be three or more and used as a ring buffer. Each buffer area 19a, 19b has a size capable of storing attribute data for one band compressed at the minimum compression rate.

  The codec ASIC 18 repeatedly writes the compressed attribute data in the plurality of buffer areas 19 a and 19 b in the work memory area 19 in order. That is, the codec ASIC 18 writes the compressed attribute data of a certain band to the buffer area 19a, writes the compressed attribute data of the next band to the buffer area 19b, and further stores the compressed attribute data of the next band. Write to the buffer area 19a.

  The copy processing unit 16 is composed of, for example, an ASIC, and the compressed image data that has been written to one of the buffer areas 15a and 15b in the work memory area 15 and the buffer areas 19a and 19b in the work memory area 19 are stored. The compressed attribute data that has been written to either of them is read out and written continuously into the page memory area 20 without a gap.

  The codec ASICs 14 and 18 and the copy processing circuit 16 may be included in the scanner unit 1 or may be included in the image processing unit 2.

  The page memory area 20 is a memory area for storing image data secured in the memory 3 and compressed by the codec ASIC 14 and attribute data compressed by the codec ASIC 18. The page memory area 20 has a size capable of continuously storing compressed image data and attribute data for at least one page.

  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, 15, 17, 19, page memory area 20, etc.) 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, in this embodiment, the main control unit 4 designates the copy processing circuit 16 with the write position of the compressed image data and the compressed attribute data in the page memory area 20. The main control unit 4 determines the size of the compressed image data stored in the buffer areas 15 a and 15 b of the work memory area 15 and / or the compressed image data stored in the buffer areas 19 a and 19 b of the work memory area 19. Based on the size of the attribute data, the writing position to the page memory area 20 is specified. In this case, the main control unit 4 may acquire the sizes of the compressed image data and attribute data from the codec ASICs 14 and 18, or the compressed data stored in the buffer areas 15a, 15b, 19a, and 19b. The size of the image data and the attribute data may be acquired directly or indirectly (via the copy processing circuit 16).

  The image data and attribute data stored in the page memory area 20 are read out and expanded, and then subjected to predetermined image processing by the image processing unit 2. The main control unit 4 manages the writing position and size of the image data (compressed) and attribute data (compressed) of each band. The main control unit 4 manages the image data (compressed) of each band and The reading position and size of the attribute data (compressed) are designated to the image processing unit 2.

  Next, the operation of the image reading apparatus will be described.

  The main control unit 4 secures the page memory area 20 and sets its address information (start address and size, or start address and end address) in the copy processing unit 16. Further, the main control unit 4 secures the work memory area 13, sets the address information (start address and size, or start address and end address) of the work memory area 13 in the read ASIC 12 and the codec ASIC 14, The memory area 15 is secured, and the address information (start address and size, or start address and end address) of the work memory area 15 is set in the codec ASIC 14 and the copy processing circuit 16. Further, the main control unit 4 secures the work memory area 17, sets the address information (start address and size, or start address and end address) of the work memory area 17 in the read ASIC 12 and the codec ASIC 18, The memory area 19 is secured, and address information (start address and size, or start address and end address) of the work memory area 19 is set in the codec ASIC 18 and the copy processing circuit 16.

  The codec ASIC 14 and the codec ASIC 18 operate in parallel as follows.

  The main control unit 4 supplies a compression command to the codec ASIC 14 for each band. The codec ASIC 14 reads out and compresses one band of image data from the work memory area 13 in accordance with a command from the main control unit 4, and compresses one band of compressed image data into one of the buffer areas 15a and 15b. Write. The codec ASIC 14 notifies the main control unit 4 of the size of the image data for one band after compression after compression.

  Further, the main control unit 4 supplies a compression command to the codec ASIC 18 for each band. The codec ASIC 18 reads out and compresses attribute data for one band from the work memory area 17 in accordance with a command from the main control unit 4, and compresses the attribute data for one band into one of the buffer areas 19a and 19b. Write. After compression, the codec ASIC 18 notifies the main control unit 4 of the size of attribute data for one band after compression.

  Note that the size of the image data before compression for one band is constant, but the size of the compressed image data for one band is not constant. Similarly, the size of attribute data before compression for one band is constant, but the size of attribute data after compression for one band is not constant.

  Further, the main control unit 4 supplies a copy command to the copy processing circuit 16, and the copy processing circuit 16 reads the image data or attribute data in the buffer area specified by the command, and is specified by the command. Write to the write position in the page memory area 20. The main control unit 4 causes the copy processing circuit 16 to write the compressed image data and attribute data continuously for each band without any gap.

  In FIG. 2, the image data and the attribute data are alternately stored in the page memory area 20, but may not be alternately. For example, image data and attribute data may be written to the page memory area 20 in the order in which writing to the work memory areas 15 and 19 is completed. That is, for example, the i-th band image data, the i-th band attribute data, the (i + 1) -th band attribute data, and the (i + 1) -th band image data may be stored in this order.

  At this time, the main control unit 4 stores the size of the compressed image data stored in the buffer areas 15 a and 15 b of the work memory area 15 and / or the buffer areas 19 a and 19 b of the work memory area 19. Based on the size of the compressed attribute data, the writing position in the page memory area 20 is specified.

  FIG. 3 is a timing chart for explaining an example of operations of the codec ASICs 14 and 18 and the copy processing circuit 16.

  The main control unit 4 operates the codec ASICs 14 and 18 and the copy processing circuit 16, for example, as shown in FIG. The codec ASIC 14 and the codec ASIC 18 operate in parallel, perform compression processing for one band and output the compressed data in almost the same time, and write to the work memory areas 15 and 19 one band at a time. When completed, the main control unit 4 is notified of the size of the compressed data and the completion of the writing.

Further, the main control unit 4 supplies a copy command to the copy processing circuit 16 in response to the writing completion notification. In accordance with the copy command, the copy processing circuit 16 has completed the writing of the band (i-1 band) immediately preceding the band (i-th band) for which the codec ASICs 14 and 18 are performing compression processing. Writing of compressed image data and attribute data to the page memory area 20 for the band is performed in parallel.

  In the case shown in FIG. 3, the compressed image data and attribute data are sequentially written to the page memory area 20, but the memory 3 can be accessed by a plurality of channels. The writing of the compressed image data and the writing of the compressed attribute data may be performed in parallel.

  As described above, according to the above-described embodiment, the codec ASIC 14 compresses image data, writes the compressed image data in the plurality of buffer areas 15a and 15b of the work memory area 15 in order, and the codec ASIC 18 Compresses the attribute data and writes the compressed attribute data to the plurality of buffer areas 19 a and 19 b in the work memory area 19 in order. The copy processing unit 16 compresses the compressed image data that has been written to any one of the plurality of buffer areas 15 a and 15 b in the work memory area 15 and one of the plurality of buffer areas 19 a and 19 b in the work memory area 19. The compressed attribute data that has been written to is read and written continuously to the page memory area 20.

  As a result, the compressed image data and attribute data are temporarily stored in the work memory areas 15 and 19 and written in the page memory area 20 continuously. Therefore, the codec ASICs 14 and 18 can operate in parallel without delay. Therefore, the use efficiency of the page memory area 20 is increased, and the delay occurring in writing the compressed image data and attribute data can be shortened.

  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 embodiment, the main control unit 4 specifies the write position in the page memory area 20, but instead, the copy processing circuit 16 may specify the write position. . In that case, the copy processing circuit 16 notifies the main control unit 4 of the writing position.

  In the above embodiment, the main control unit 4 may incorporate the copy processing circuit 16.

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

4 Main control unit (an example of control unit)
14 ASIC for codec (an example of image data compression unit)
15 Work memory area (example of first buffer)
16 Copy processing circuit (an example of a copy processing unit)
18 ASIC for codec (example of attribute data compression unit)
19 Work memory area (example of second buffer)
20 page memory area

Claims (3)

A first buffer having a plurality of buffer areas for image data of image data and attribute data generated by image reading;
A second buffer having a plurality of buffer areas for the attribute data;
An image data compression unit that compresses the image data and sequentially writes the compressed image data into the plurality of buffer areas of the first buffer;
An attribute data compression unit that compresses the attribute data and sequentially writes the compressed attribute data into the plurality of buffer areas of the second buffer;
The compressed image data that has been written to any of the plurality of buffer areas of the first buffer, and the compression that has been written to any of the plurality of buffer areas of the second buffer A copy processing unit that reads out the attribute data that has been read and writes it continuously to the page memory area
A control unit for designating a writing position of the compressed image data and the compressed attribute data in the page memory area;
The control unit is configured to store the compressed image data size stored in the buffer areas of the first buffer and / or the compressed data stored in the buffer areas of the second buffer. Based on the size of the attribute data specified, the write position to the page memory area is specified,
The page memory area is secured in a memory of a plurality of channels,
The copy processing unit writes the compressed image data and the compressed attribute data to the page memory area in parallel;
An image reading apparatus. A first buffer having a plurality of buffer areas for image data of image data and attribute data generated by image reading;
A second buffer having a plurality of buffer areas for the attribute data;
An image data compression unit that compresses the image data and sequentially writes the compressed image data into the plurality of buffer areas of the first buffer;
An attribute data compression unit that compresses the attribute data and sequentially writes the compressed attribute data into the plurality of buffer areas of the second buffer;
The compressed image data that has been written to any of the plurality of buffer areas of the first buffer, and the compression that has been written to any of the plurality of buffer areas of the second buffer A copy processing unit that reads out the attribute data that has been read and writes it continuously to the page memory area,
The copy processing unit is configured to store the compressed image data size stored in the plurality of buffer areas of the first buffer and / or the compression stored in the plurality of buffer areas of the second buffer. Based on the size of the attribute data that has been specified, the write position to the page memory area is specified,
The page memory area is secured in a memory of a plurality of channels,
The copy processing unit writes the compressed image data and the compressed attribute data to the page memory area in parallel;
Images reader said. The image data and the attribute data are compressed for each band,
Each of the plurality of buffer areas of the first buffer has a size capable of storing the compressed image data for one band at a minimum compression rate,
Each of the plurality of buffer areas of the second buffer has a size capable of storing the compressed attribute data for one band at a minimum compression rate,
The image data compression unit sequentially writes the compressed image data to the plurality of buffer areas of the first buffer, band by band,
The attribute data compression unit sequentially writes the compressed attribute data to the plurality of buffer areas of the second buffer, one band at a time;
The image reading apparatus according to claim 1 or claim 2 wherein.

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