JP6278245B2 - Image processing device - Google Patents

Description

  The present invention relates to an image processing apparatus.

  When an image processing apparatus writes image data into a buffer memory, reads the image data, and performs subsequent processing, the image data is buffered while securing a difference between the read address and the write address to a predetermined value or more. It is written in the memory (see, for example, Patent Document 1). Therefore, when the difference between the read address and the write address cannot be secured above a predetermined value, the writing of the image data is interrupted.

  Another image processing apparatus writes image data obtained by image reading into a predetermined storage area, reads the image data and performs subsequent processing, and interrupts image reading when the area for writing is insufficient. (For example, refer to Patent Document 2).

JP-A-5-56278 JP 2010-251917 A

  However, when real-time image processing is required such as first copy (copy processing of the first page at the start of copying), it is not preferable that the data flow be interrupted as described above.

  The present invention has been made in view of the above problems, and an object of the present invention is to obtain an image processing apparatus in which a data flow is less likely to be interrupted.

  An image processing apparatus according to the present invention includes a memory that secures a buffer area of a predetermined size, an image processing unit that executes predetermined image processing on subband data obtained by dividing one page of image data, A compression processing unit that compresses the subband data and generates the compressed subband data; a decompression processing unit that decompresses the compressed subband data into the subband data; and (a) one before the image processing (B) sequentially writing the compressed subband data for one page to the buffer area, and (b) a data store unit for sequentially writing the compressed subband data for one page after the image processing to the buffer area; A data load unit that sequentially reads the compressed subband data from the buffer area. The data store unit, in parallel with the reading of the compressed subband data by the data load unit, (c) the difference between the write position of the data store unit and the read position of the data load unit The compressed subband data after the image processing is sequentially written in the buffer area until the value becomes equal to or less than a predetermined value, and (d1) a write position of the data store unit and a read position of the data load unit When the difference between the two is less than or equal to a predetermined value, the writing position of the compressed subband data after the image processing is switched to a saving area in the buffer area, and (d2) the writing position of the data store section When the difference from the read position of the data load unit exceeds the predetermined value, the write position of the data store unit is changed from the save area in the buffer area to the save area. Switch to continuous to said compressed sub-band data after the image processing immediately before the switching of the write position to. Here, the save area is included in an area where the compressed subband data before the image processing is not written in the buffer area.

  According to the present invention, it is possible to obtain an image processing apparatus in which the data flow is less likely to be interrupted.

  These and other objects, features and advantages of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.

FIG. 1 is a block diagram showing a configuration of an image forming apparatus having an image processing apparatus according to an embodiment of the present invention. FIG. 2 is a diagram illustrating an example of image data and subband data. FIG. 3 is a diagram for explaining writing and reading of compressed subband data CSBij and CPSBij with respect to the buffer area (1/4). FIG. 4 is a diagram for explaining writing and reading of compressed subband data CSBij and CPSBij with respect to the buffer area (2/4). FIG. 5 is a diagram for explaining writing and reading of compressed subband data CSBij and CPSBij with respect to the buffer area (3/4). FIG. 6 is a diagram for explaining writing and reading of compressed subband data CSBij and CPSBij with respect to the buffer area (4/4). FIG. 7 is a diagram showing a configuration example of a descriptor used in the image processing apparatus 13 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 forming apparatus having an image processing apparatus according to an embodiment of the present invention.

  The image forming apparatus 1 is an apparatus such as a copier or a multifunction machine. The image forming apparatus 1 includes an image reading device 11, a printing device 12, an image processing device 13, and an operation panel 14. The image reading device 11 is an internal device that optically reads a document image and generates image data of the document image. The printing device 12 is an internal device that prints an image based on image data after image processing by the image processing device 13. The image processing device 13 performs predetermined image processing (such as filter processing) on the document image generated by the image reading device 11. The operation panel 14 includes a display device such as a liquid crystal display that displays various types of information to the user, and an input device that detects a user operation.

  The image processing device 13 includes an arithmetic processing device 21 and a memory 22.

  The arithmetic processing unit 21 includes a computer, an application specific integrated circuit (ASIC), and the like, and realizes various processing units by software and / or hardware. The memory 22 is a main storage device such as a RAM.

  The arithmetic processing device 21 includes a control unit 31, an image processing unit 32, a compression processing unit 33, an expansion processing unit 34, a memory area management unit 35, a data store unit 36, and a data load unit 37.

  The control unit 31 controls the image reading device 11, the printing device 12, the operation panel 14, and the like, and inputs / outputs data to / from the image reading device 11 and the printing device 12.

  The image processing unit 32 performs predetermined image processing on subband data obtained by dividing one page of image data.

  The data length of the subband data is constant, but the data length of the compressed subband data changes because the compression rate changes depending on the data value. The sub-band data is data obtained by dividing the band data in the image data in the main scanning direction. The band data is data composed of a predetermined number of lines in the image data.

  FIG. 2 is a diagram illustrating an example of image data and subband data. The image data for one page shown in FIG. 2 has n bands # 1 to #n. Each band #i (i = 1,..., N) has a predetermined number of lines. In this example, the band data of band #i has subband data SBi1 to SBi4.

  The compression processing unit 33 compresses the subband data (subband data SBij before image processing or subband data PSBij after image processing), and compressed subband data (subband data CSBij before image processing or after image processing). Subband data CPSBij).

  The decompression processing unit 34 converts the compressed subband data (subband data CSBij before image processing or subband data CPSBij after image processing) into original subband data (subband data SBij before image processing or after image processing). To subband data PSBij).

  The memory area management unit 35 secures a buffer area of a predetermined size in the memory 22. The size of the buffer area is equal to the total size of a plurality of compressed subband data obtained by compressing a plurality of subband data obtained by dividing one page of image data at the worst compression rate by a predetermined margin. Is the size obtained by adding The worst compression rate is specified in advance through experiments or the like.

  FIGS. 3, 4, 5, and 6 are diagrams for explaining writing and reading of the compressed subband data CSBij and CPSBij with respect to the buffer area.

  The data store unit 36 sequentially writes (a) one page of compressed subband data CSBij before the image processing of the image processing unit 32 into the buffer area 61, and (b) one page of the image after the image processing. The compressed subband data CPSBij is written in the buffer area 61 in order. The data store unit 36 writes the compressed subband data CSBij and CPSBij in order along the scanning direction. The data load unit 37 sequentially reads the compressed subband data CSBij and CPSBij from the buffer area 61. The data load unit 37 sequentially reads the compressed subband data CSBij and CPSBij along the scanning direction.

  In this embodiment, as shown in FIG. 3, the data store unit 36 sequentially writes the compressed subband data CSBij for one page before image processing from the rear end of the predetermined offset area 71, As shown in FIG. 4, compressed subband data CPSBij for one page after image processing is sequentially written from the tip of the offset area 71. The offset area 71 is set at a predetermined size at the head of the buffer area 61.

  In parallel with the reading of the compressed subband data CSBij by the data load unit 37, the data store unit 36 determines that (c) the difference between the write position of the data store unit 36 and the read position of the data load unit 37 is predetermined. The compressed subband data CPSBij after image processing is sequentially written in the buffer area 61 until the value becomes equal to or smaller than the value, and (d1) between the write position of the data store unit 36 and the read position of the data load unit 37 When the difference is equal to or smaller than the predetermined value, the writing position of the compressed subband data CPSBij after the image processing is switched to the save area 72 in the buffer area 61 as shown in FIGS. 5 and 6 (d2 When the difference between the write position of the data store unit 36 and the read position of the data load unit 37 exceeds the above-mentioned predetermined value, as shown in FIG. 36 writing position, from the save area 72 in the buffer regions 61, switch to continuous compressed sub-band data CPSBij after image processing immediately before the switching of the write position into the save area 72. When the write position reaches the end of the buffer area 61, the write position is returned to the top of the buffer area 61.

  The save area 72 is included in the buffer area 61 where the compressed subband data CSBij before image processing is not written.

  In this embodiment, the save area 72 has the compression rate up to the present time and the remaining compressed subband data before the writing of the compressed subband data CSBij before image processing for one page to the buffer area 61 is completed. The area where the compressed sub-band data CSBij before image processing for one page is written is predicted based on the number of and the worst compression rate so that it is included in the buffer area outside the predicted area. Is set. As a result, the save area 72 is more reliably set in an area where the compressed subband data CSBij before image processing for one page is not written.

  For example, in the case shown in FIG. 6, the compressed subband data CPSB34 next to the compressed subband data CPSB33 is written in the save area 72 after switching the writing position, and the next compressed subband data CPSB41 is also The next compressed subband data CPSB42 written to the save area 72 is written not to the save area 72 but continuously to the compressed subband data CPSB33 after switching the writing position.

  In this embodiment, the data store unit 36 connects the compressed subband data CPSBij after the image processing in the order of writing in a list structure, and (e1) writes to the save area 72. The compressed subband data CPSBij after the image processing immediately before the position switching and the compressed subband data CPSBij after the image processing immediately after the writing position switching to the save area 72 are connected in a list structure (e2) List structure of compressed subband data CPSBij after image processing immediately before switching of the writing position from the save area 72 and compressed subband data CPSBij after image processing immediately after switching of the write position from the save area 72 Connect with.

  Note that the compressed subband data CSBij before image processing is similarly connected in a list structure.

  The data load unit 37 sequentially reads the compressed subband data CSBij before image processing and the compressed subband data CPSBij after image processing in accordance with this list structure.

  Here, the list structure using descriptors will be described.

  FIG. 7 is a diagram showing a configuration example of a descriptor used in the image processing apparatus 13 in FIG.

  The descriptor 81 has a data start address, a data size, a subsequent descriptor address, and a final descriptor flag.

  “Data start address” indicates the head address of the block storage area for storing the compressed subband data CSBij and CPSBij.

  “Data size” indicates the data size of the data stored in the block storage area.

  “Subsequent descriptor address” indicates the start address of the next descriptor. If there is no next descriptor, NULL is set in the subsequent descriptor address.

  The “final descriptor flag” is a flag indicating whether or not it is a final descriptor. When the next descriptor exists, the final descriptor flag is set to 1. When the next descriptor does not exist, the final descriptor flag is set to zero.

  That is, a plurality of descriptors 81 are respectively assigned to a plurality of compressed subband data, and the plurality of descriptors 81 form a list structure, and the compressed subband data is connected by the list structure.

  When writing the compressed subband data to the buffer area 61, the memory area management unit 35 continuously sets block storage areas in the buffer area 61 as necessary. The descriptor 81 is generated. The descriptor 81 itself is stored in an area outside the buffer area 61.

  Next, the operation of the image processing apparatus 13 will be described.

  The memory area management unit 35 secures the buffer area 61 from the free area of the memory 22.

  The compression processing unit 33 compresses image data for one page for each subband data SBij, and generates compressed subband data CSBij before image processing.

  Then, the data store unit 36 continuously writes the compressed subband data CSBij before image processing in the scanning order as shown in FIG. At that time, the memory area management unit 35 sets a block storage area and uses the descriptor 81 to manage the compressed subband data CSBij before image processing.

  In parallel with the writing of the compressed subband data CSBij before the image processing, the data load unit 37 sequentially reads the compressed subband data CSBij before the image processing.

  The decompression processing unit 34 decompresses the read compressed subband data CSBij into subband data SBij, and the image processing unit 32 executes predetermined image processing on the subband data SBij. Then, the compression processing unit 33 compresses the subband data PSBij after the image processing into the compressed subband data CPSBij. As shown in FIG. 4, the data store unit 36 writes the compressed subband data CPSBij.

  Since the size of the compressed subband data CPSBij after the image processing varies depending on the compression rate, it is usually different from the size of the compressed subband data CSBij before the image processing.

  Therefore, even if the processing speeds of the decompression processing unit 34, the image processing unit 32, and the compression processing unit 33 are constant, the read position of the compressed subband data CSBij before image processing and the compressed subband data after image processing The difference from the writing position of CPSBpq changes with time.

  When the data store unit 36 writes the compressed subband data CPSBij after image processing, the data store unit 36 determines whether or not the difference is equal to or smaller than a predetermined value. If this difference is not less than the predetermined value, the data store unit 36 continuously writes the compressed subband data CPSBij to the previous compressed subband data CPSBij. On the other hand, if the difference is equal to or smaller than the predetermined value, the data store unit 36 writes the compressed subband data CPSBij in the save area 72.

  Thereafter, if the difference between the write position and the read position remains below a predetermined value, the data store unit 36 continuously writes the next compressed subband data CPSBij in the save area 72. If the difference between the write position and the read position is not less than the predetermined value, the data store unit 36 performs the next compressed so that it is continuous with the compressed subband data CPSBij immediately before switching the write position to the save area 72. Write subband data CPSBij.

  As described above, according to the above embodiment, the data store unit 36 performs (c) the write position of the data store unit 36 and the read of the data load unit 37 in parallel with the reading of the compressed subband data CSBij. The compressed subband data CPSBij after the image processing is sequentially written in the buffer area 61 until the difference between the position and the position becomes a predetermined value or less. (D1) Between the writing position and the reading position When the difference falls below a predetermined value, the writing position of the compressed subband data CPSBij after image processing is switched to the save area 72 in the buffer area 61, and (d2) between the writing position and the reading position. If the difference exceeds the predetermined value, the compressed subband data after image processing immediately before switching of the write position from the save area 72 to the save area 72 is changed to the write position of the data store unit 36. It switched so as to be continuous to PSBij. Here, the save area 72 is included in the buffer area 61 where the compressed subband data CSBij before image processing is not written.

  As a result, the compressed subband data CPSBij after the image processing in the buffer area 61 can be written without being overwritten by the compressed subband data CSBij before the image processing by writing the compressed subband data CPSBij after the image processing. Since interruptions are less likely to occur, it is possible to obtain an image processing apparatus that is less likely to cause interruptions in a series of data flows via the buffer area 61 that require real-time performance.

  Various changes and modifications to the above-described embodiment will be apparent to those skilled in the art. Such changes and modifications may be made without departing from the spirit and scope of the subject matter and without diminishing its intended advantages. That is, such changes and modifications are intended to be included within the scope of the claims.

  For example, in the above embodiment, when there is no area for writing compressed subband data CPSBij after image processing in the save area 72, the control unit 31 displays a warning message such as a memory full error message, for example, on the operation panel. 14 may be displayed and displayed to determine whether to stop the image processing for one page of image data or to re-execute the image processing for one page of image data based on a user operation. In this case, when the control unit 31 determines to re-execute image processing for one page of image data, after the writing of the compressed subband data CSBij for one page before image processing to the buffer area 61 is completed, ( f) The data load unit 36 starts reading the compressed subband data CSBij before the image processing from the buffer area 61, and (g) the data store unit 37 writes the compressed subband data CPSBij after the image processing. To start.

  The present invention is applicable to, for example, an image forming apparatus.

DESCRIPTION OF SYMBOLS 13 Image processing apparatus 22 Memory 61 Buffer area 32 Image processing part 33 Compression processing part 34 Decompression processing part 36 Data store part 37 Data load part

Claims (5)

Memory that secures a buffer area of a predetermined size,
An image processing unit that executes predetermined image processing on subband data obtained by dividing one page of image data;
A compression processing unit that compresses the subband data and generates the compressed subband data;
A decompression processing unit for decompressing the compressed subband data into the subband data;
(A) sequentially writing the compressed subband data for one page before the image processing into the buffer area; and (b) storing the compressed subband data for one page after the image processing in the buffer area. The data store part to write in order,
A data load unit that sequentially reads the compressed subband data from the buffer area;
In parallel with the reading of the compressed subband data by the data load unit, the data store unit has a predetermined difference between (c) the write position of the data store unit and the read position of the data load unit. The compressed subband data after the image processing is sequentially written in the buffer area until the value becomes less than or equal to a value, (d1) between the writing position of the data store unit and the reading position of the data load unit When the difference between the two is less than a predetermined value, the writing position of the compressed subband data after the image processing is switched to a saving area in the buffer area, and (d2) the writing position of the data store unit and the data When the difference from the read position of the load unit exceeds the predetermined value, the write position of the data store unit is changed from the save area in the buffer area to the save area. Switching so as to continue to the compressed sub-band data after the image processing immediately before the switching position,
The save area is included in an area where the compressed subband data before the image processing is not written in the buffer area;
An image processing apparatus.   The data store unit sequentially connects the compressed subband data after the image processing in a list structure in a writing order, and (e1) the image immediately before switching the writing position to the save area The compressed subband data after processing and the compressed subband data after image processing immediately after switching of the writing position to the save area are connected in the list structure, and (e2) from the save area The list structure includes the compressed subband data after the image processing immediately before the switching of the writing position and the compressed subband data after the image processing immediately after the switching of the writing position from the save area in the list structure. The image processing apparatus according to claim 1, wherein the image processing apparatus is connected.   The data store unit sequentially writes the compressed subband data for one page before the image processing from the rear end of a predetermined offset area, and for one page after the image processing from the front end of the offset area. The image processing apparatus according to claim 1, wherein the compressed subband data are sequentially written. When there is no area for writing the compressed subband data after the image processing in the save area, a warning message is output and the image processing for one page of image data is stopped based on a user operation. Or a control unit that determines whether to re-execute the image processing on one page of image data,
When the control unit determines to re-execute the image processing on one page of image data, after the writing of the compressed subband data for one page before the image processing to the buffer area is completed, (f ) The data load unit starts reading the compressed subband data before the image processing from the buffer area, and (g) the data store unit stores the compressed subband data after the image processing. To start writing,
The image processing apparatus according to claim 1, wherein:   The save area is an area in which the compressed subband data before the image processing for one page is written before the writing of the compressed subband data before the image processing for one page to the buffer area is completed. The image processing apparatus according to claim 1, wherein the image processing device is included in a region outside the predicted region within the buffer region.

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