JP5663364B2 - Image forming apparatus and control method thereof - Google Patents

Description

  Embodiments described herein relate generally to an image forming apparatus having a function of, for example, compression processing for image data, and a control method thereof.

  An image forming apparatus such as a multifunction copying machine (MFP) prints image data scanned from a document or image data input from a network-connected external device (so-called client terminal) on paper or compresses it to a small size. (For example, Patent Document 1).

JP 2009-71832 A

  Faster processing is desired for compression of image data.

  An object of an embodiment of the present invention is to provide an image forming apparatus capable of improving the processing speed and a control method thereof.

An image forming apparatus according to an embodiment of the present invention includes a decoding unit that decodes image data to be compressed, an edge detection unit that detects an edge of a character image region in the decoded image data, and a character image in the decoded image data Layout analysis means for analyzing the layout of the area based on the detection result of the edge detection means, and detecting a plurality of character image areas included in the decoded image data based on the analysis result of the layout analysis means; than the sum of the capacitance of the overhead data added respectively any two of the character image area in the character image data size and the two character image data when compressed, respectively, in the image area, the two character image region thereof the character image data size and the character image data when compressing the region encompassing On condition that the sum is small and the capacity of the overhead data to be pressurized, comprising integrating means for integrating the two character image areas thereof as one character image region.

The block diagram which shows the structure of one Embodiment of this invention. The figure which shows the block of the processing function of CPU and image processing processor in one Embodiment. The figure which shows the load condition table of the performance monitor in one Embodiment. The flowchart which shows the process of CPU in one Embodiment. The flowchart which shows the process of the image processor in one Embodiment. The flowchart which shows the process of the performance monitor in one Embodiment. The figure which shows the example of the some character area in connection with one Embodiment.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
In FIG. 1, reference numeral 1 denotes an image forming apparatus such as a composite copying machine (MFP). The MFP 1 has a plurality of functions such as a copy function, a scan function, and a print function. The MFP 1 includes an image processing circuit 2, a control panel 3, a scanner 4, and a printer (also referred to as a printer engine) 5.

The image processing circuit 2 includes a CPU 10 as a controller, a data bus 11 for data transfer, a ROM 12 for program storage, a main memory (RAM) 13 for data storage, a hard disk drive (HDD) 14, a control panel interface (I / I). F) 15, fabric network type interface (I / F) 16, and external interface (I / F) 17, system interfaces (I / F) 18a, 18b, 18c, image processors 20a, 20b, 20c, local memory 21a , 21b, 21c, and a performance monitor 30. The control panel 3 sets operation conditions of the MFP 1 and displays the operation state of the MFP 1, and includes a display unit 3a and an operation unit 3b. The scanner 4 optically reads an image of a document set on the MFP 1. The printer 5 prints image data on paper.

  A plurality of client terminals (for example, personal computers) 50 are connected to the external interface 17 via a network cable 40. These client terminals 50 generate image data by various built-in application programs (word processor, spreadsheet, presentation, DTP software, etc.), and send the generated image data to the MFP 1. The fabric network type interface 16 can be connected regardless of the form of the interface of the scanner 4 and the interface of the printer 5 and without deteriorating the transfer performance.

  The image processors 20a, 20b, and 20c are dynamic reconfigurable processors (DRP; also referred to as a dynamic reconfiguration processor). The character compression processing unit 37 and the background compression processing unit 38 shown in FIG. The character image data separated by the character / background separation processing unit 36, which will be described later, is compressed by MMR encoding and separated by the character / background separation processing unit 36. The background image data is compressed by JPEG encoding.

The performance monitor 30 functions as a load status detection unit that detects the load status of each processing of the image processors 20a, 20b, and 20c, and events (commands) that occur before and after work execution in each image processor. Event occurrence counter for counting occurrences of events, and calculating the occurrence rate of events. If the occurrence rate is high, the processing load is large, and if the occurrence rate is low, the processing load is small. For example, the number of events per sample time is counted, the number of clock cycles per sample time is counted, and the event occurrence rate (IPC) per cycle of workload is calculated by the following formula using these count numbers. To do.
IPC = (number of events per sample time) / (number of clock cycles per sample time)
Further, the performance monitor 30 sequentially updates and stores the detected load status in the internal load status table shown in FIG. That is, when the load status of each of the image processors 20a, 20b, and 20c is 10%, as indicated by dots, 10% corresponding positions of the items GP1, GP2 , and GP3 corresponding to the image processors 20a, 20b, and 20c, respectively. Is stored with logic “1”. When the load status of the image processor 20a is 0% and the load status of the image processors 20b and 20c is 50%, respectively, as indicated by the hatched lines, the logical “0” in the position corresponding to the 0% of the item GP1 corresponding to the processor 20a. 1 "is stored, and logic" 1 "is stored at the 50% corresponding position of the items GP2 and GP3 corresponding to the image processors 20b and 20c.

The CPU 10 includes the following means (1) to (8) that function as the processing units in FIG.
(1) Decoding means (decoding processing unit 31) for decoding image data to be compressed.

  (2) Edge detection means (edge detection processing unit 32) for detecting the edge of the character image area in the decoded image data.

(3) Layout analysis means (layout analysis processing unit 33) for analyzing the layout of the character image area in the decoded image data based on the detection result of the edge detection processing unit 32.

  (4) A plurality of character image regions included in the decoded image data are detected based on the analysis result of the layout analysis means, and character image data of any two character image regions in each detected character image region are respectively MMR. On the condition that the total of the character image data size when the compression processing is performed by encoding is smaller than the character image data size when the region including the two character image regions is compressed by MMR encoding. Integration means (character area integration processing unit 34) for integrating the character image areas as one character image area.

(5) Low resolution conversion means (low resolution conversion processing unit 35) for reducing the resolution of the decoded image data.

(6) the image data obtained by the decoding, the respective character image region and integrated no character image area obtained by integrating the integrated unit corresponding separation means for separating the character image data and background image data (character / background separation processing Part 36). The background image data includes a photographic image.

  (7) Control means for dividing the separated character image data and background image data into a plurality of parts at a rate corresponding to the load status detected by the performance monitor 30 and assigning them to the image processors 20a, 20b, 20c. The number of divisions is increased or decreased according to the required processing speed and within the range of the number of image processors.

  (8) File forming means (file forming processing unit 39) for converting character image data and background image data compressed by the image processing processors 20a, 20b, and 20c into PDF files.

  Next, the operation will be described. The processing of the CPU 10 is shown in the flowchart of FIG. 4, the processing of the image processing processors 20a, 20b, and 20c is shown in the flowchart of FIG. 5, and the processing of the performance monitor 30 is shown in the flowchart of FIG.

Image data read by the scanner 4 or input image data sent from the client terminal 50 is temporarily stored in the hard disk drive 14 via the system bus 11. The CPU 10 downloads a necessary image processing program from the main memory 13. The image processors 20a, 20b, and 20c download necessary image processing programs and circuit information for forming a processing unit from the low-power memories 21a, 21b, and 21c.

The CPU 10 requests the performance monitor 30 to confirm the load status of the image processors 20a, 20b, and 20c (step 101), and acquires the load status of the image processors 20a, 20b, and 20c from the performance monitor 30 (step 102). . Then, the CPU 10 decodes the image data for one page stored in the hard disk drive 14 into raw image data, detects the edge of the character image area in the decoded image data, and layout of the character image area in the decoded image data. Is analyzed based on the result of the edge detection (step 104). Further, the resolution of the decoded image data is reduced (step 105).

The CPU 10 detects a plurality of character image regions in the decoded image data based on the result of the layout analysis, extracts any two character image regions from the detected plurality of character image regions, and extracts the extracted two character image regions The character image data sizes S1 and S2 when the character image data is compressed by MMR encoding are detected (step 106). Then, the total (= S1 + S2) of the detected character image data sizes S1 and S2 is compared with the character image data size S3 when the region including the two character image regions is compressed by MMR encoding (step S3). 107).

  When the sum of the character image data sizes S1 and S2 is smaller than the character image data size S3 (YES in step 107), the CPU 10 integrates the two extracted character image regions as one character image region (step 108). Then, it is determined whether or not the remaining number of character image areas not yet extracted from the detected plurality of character image areas is less than one (step 109). If the sum of the character image data sizes S1 and S2 is not smaller than the character image data size S3 (NO in step 107), the process proceeds to the determination in step 109 without integration.

  If the remaining number of character image areas that are not to be extracted is less than one (NO in step 109), the CPU 10 determines whether the integrated one character image area and the character image area that has not yet been extracted. An arbitrary one is extracted, and the character image data S1 and S2 of the two extracted character image regions are detected again (step 106). Then, the total of the detected character image data sizes S1 and S2 (= S1 + S2) is compared with the character image data size S3 when the region including the two character image regions is compressed by MMR encoding (step S3). 107), the same processing as described above is repeated.

When the remaining number of character image areas that are not to be extracted becomes less than one (YES in step 109), the CPU 10 converts the decoded image data into the integrated character image area and the character image area that has not been integrated. Are separated into character image data and background image data (background and photograph) respectively corresponding to (step 110). Then, the separated character image data and background image data are divided into a plurality at a rate corresponding to the load status acquired from the performance monitor 30 and assigned to the image processors 20a, 20b, and 20c (step 111).

For example, considering that the size of one integrated character image data is 1 Mbyte and that one integrated character image data is assigned to the image processors 20a, 20b, and 20c, the load status of the image processors 20a, 20b, and 20c is as follows. If each of them is 10%, the integrated character image data is divided into three (almost equal) character image data for 3333.4 Kbytes, character image data for 3333.3 Kbytes, and character image data for 3333.3 Kbytes. Assigned to the image processors 20a, 20b, 20c. If the load status of the image processor 20a is 0% and the load status of the image processors 20b and 20c is 50%, the integrated character image data is 5000Kbyte character image data, 2500Kbyte character image data, 2500Kbyte worth. The first character image data is assigned to the image processor 20a, and the second and third character image data are assigned to the image processors 20b and 20c. The number of divisions may be increased or decreased as appropriate according to the requested processing speed.

  After the assignment is finished, the CPU 10 instructs the image processors 20a, 20b, and 20c to start the compression process (step 112), and actually assigns the assigned character image data and background image data to the image processors 20a, 20b, and 20c. 20c (step 113). Then, the character image data and the background image data compressed by the image processors 20a, 20b, and 20c are received (step 114) and converted into a single PDF file (step 115).

On the other hand, when receiving a request signal from the performance monitor 30 (YES in step 201), the image processors 20a, 20b, and 20c accept the load status detection from the performance monitor 30 (step 202). When the image processor 20a, 20b, 20c receives a start instruction from the CPU 10 (YES in step 203), the image processor 20a, 20b, 20c forms the character compression processing unit 37 of FIG. 2, and character image data sent from the CPU 10 is encoded by MMR encoding. Compression processing is performed (step 204). Subsequently, the background compression processing unit 38 of FIG. 2 is formed instead of the character compression processing unit 37, and the background image data sent from the CPU 10 is compressed by JPEG encoding (step 205). The compressed character image data and background image data are sent to the CPU 10 (step 206).

  The performance monitor 30 polls the image processor 20a, 20b, 20c for a load status confirmation request signal (step 301) and detects the processing load status (step 302). Then, the detection results are sequentially updated and stored in the load status table. Further, when the load status confirmation is requested from the CPU 10 (YES in step 304), the performance monitor 30 notifies the CPU 10 of the content (load status) of the load status table (step 305).

  The image data for one page includes a plurality of character image areas (also referred to as character planes) A, B, C, D, E, and F, for example, as shown in FIG. The character image area A is composed of a plurality of character lines A1, A2,... An, and the character image area B is composed of a plurality of character lines B1, B2,. The character image area C includes character lines C1 and C2, the character image area D includes character lines D1 and D2, the character image area E includes character lines E1 and E2, and the character image area F includes character lines F1 and F2.

  When character image data corresponding to each of these character image areas is compressed by MMR encoding, arrangement data Xa, Xb, Xc, Xd, Xe, and Xf indicating the arrangement of each character image data on the page are character image data. Each is added as overhead data. The presence of these overhead data is a factor that hinders the improvement of the compression ratio of character image data.

The image data itself is compressed to about 1/40 on average with a general reference (about 700 images). From this, when converting the amount of overhead data added to one character image data into the number of pixels of the image,
240 bytes × 8 pixels / byte × 40 = 76,800 pixels.

The character image data size S when one character image region having a size (area) s (= w × h) having a width w and a height h is compressed into a PDF file can be estimated as follows.
S = (w × h) ÷ 8 ÷ 40 + 240
When the character image area A of size s1 (= w × h) is applied to this, the data size S1 when the character image area A is compressed into a PDF file can be estimated as follows.
S1 = s1 / (8.40) +240
The character image data S2 when the character image area B of size s2 (= w × h) is compressed into a PDF file can be estimated as follows.
S2 = s2 / (8.40) +240
The character image data size S3 when the region (size s3) including both the character image regions A and B is compressed into a PDF file can be estimated as follows.
S3 = s3 / (8.40) +240
As described above, if the sum of the character image data sizes S1 and S2 is smaller than the character image data size S3, two character image areas A and B are integrated as one character image area, so two are originally required. The overhead data that should be reduced can be reduced to one. As a result, it is possible to improve the compression rate and thus the processing speed. As for the file size, a reduction effect of 10% to 20% can be obtained.

  Since the character image data and the background image data are divided into a plurality of pieces and assigned to the image processors 20a, 20b, and 20c for parallel processing, the processing speed can be improved in this respect as well.

  Since character image data and background image data are divided and assigned at a rate according to the processing load of the image processors 20a, 20b, and 20c, the waiting time for processing due to uneven processing load is eliminated, and the efficiency of compression processing is improved. To do. This also greatly contributes to an improvement in processing speed.

In the above embodiment, the three image processing processors 20a, 20b, and 20c are used. However, the number can be selected as appropriate. In addition, the said embodiment is shown as an example and is not intending limiting the range of invention. The novel embodiment can be implemented in various other forms, and various omissions, rewrites, and changes can be made without departing from the spirit of the invention. The scope of the invention is included in the gist of these embodiments and modifications, and is included in the invention described in the claims and the equivalents thereof.
The invention described in the scope of the original claims of the present application will be added below.
[1]
Of the plurality of character image areas included in the image data to be compressed, the total of the character image data size when any two character image areas are compressed respectively compresses the area including the two character image areas. Integration means for integrating the two character image areas as one character image area on condition that the character image data size is smaller than that when processed;
An image forming apparatus comprising:
[2]
Decoding means for decoding image data to be compressed;
Edge detection means for detecting an edge of a character image area in the decoded image data;
Layout analysis means for analyzing a layout of a character image area in the decoded image data based on a detection result of the edge detection means;
Further comprising
The integration unit detects a plurality of character image regions included in the decoded image data based on the analysis result of the layout analysis unit, and character image data of any two character image regions in each detected character image region. The two character image areas are combined into one character image, provided that the total size of the character image data when compressed is smaller than the character image data size when the area including the two character image areas is compressed. Merge as text image area,
The image forming apparatus as described in [1].
[3]
Compression means for compressing character image data respectively corresponding to the character image area integrated by the integration means and the character image area not integrated among the decoded image data,
The image forming apparatus according to [2], further comprising:
[4]
Separating means for separating the decoded image data into character image data and background image data respectively corresponding to the character image area integrated by the integrating means and the character image area not integrated;
Character compression means for compressing the separated character image data;
Background compression means for compressing the separated background image data;
A filing means for filing the compressed character image data and background image data;
[2] The image forming apparatus according to [2].
[5]
The image forming apparatus according to [4], wherein the character compression unit and the background compression unit are a plurality of image processors.
[6]
Control means for dividing the separated character image data and background image data into a plurality of parts and assigning them to the image processors;
The image forming apparatus according to [5], further comprising:
[7]
Load status detection means for detecting the load status of processing of each image processor;
A control unit that divides the separated character image data and background image data into a plurality of parts at a rate according to the detected load situation and assigns them to each image processor;
The image forming apparatus according to [2], further comprising:
[8]
Of the plurality of character image areas included in the image data to be compressed, the total of the character image data size when any two character image areas are compressed respectively compresses the area including the two character image areas. The two character image areas are integrated as one character image area on the condition that the character image data size is smaller than that when processing.
A control method for an image forming apparatus.

  DESCRIPTION OF SYMBOLS 1 ... MFP, 4 ... Scanner, 5 ... Printer, 10 ... CPU, 20a, 20b, 20c ... Image processor (compression means), 30 ... Performance monitor (load condition detection means), 50 ... Client terminal.

Claims (7)

Decoding means for decoding image data to be compressed;
Edge detection means for detecting an edge of a character image area in the decoded image data;
Layout analysis means for analyzing a layout of a character image area in the decoded image data based on a detection result of the edge detection means;
When a plurality of character image areas included in the decoded image data are detected based on the analysis result of the layout analysis means, and character image data of any two character image areas in each detected character image area are respectively compressed. Character image data size when the area including the two character image areas is subjected to compression processing rather than the sum of the character image data size and the capacity of overhead data added to each of the two character image data. Integration means for integrating the two character image areas as one character image area on the condition that the total amount of overhead data added to the image data is small;
An image forming apparatus comprising: Compression means for compressing character image data respectively corresponding to the character image area integrated by the integration means and the character image area not integrated among the decoded image data,
The image forming apparatus according to claim 1, further comprising: Separating means for separating the decoded image data into character image data and background image data respectively corresponding to the character image area integrated by the integrating means and the character image area not integrated;
Character compression means for compressing the separated character image data;
Background compression means for compressing the separated background image data;
A filing means for filing the compressed character image data and background image data;
The image forming apparatus according to claim 1, further comprising:   The image forming apparatus according to claim 3, wherein the character compression unit and the background compression unit are a plurality of image processors. Control means for dividing the separated character image data and background image data into a plurality of parts and assigning them to the image processors;
The image forming apparatus according to claim 4, further comprising: Load status detection means for detecting the load status of processing of each image processor;
A control unit that divides the separated character image data and background image data into a plurality of parts at a rate according to the detected load situation and assigns them to each image processor;
The image forming apparatus according to claim 5 , further comprising: Decode the image data to be compressed,
Detecting an edge of a character image area in the decoded image data;
The layout of the character image area in the image data the decoded and analyzed on the basis of the edge detection result,
Character image data size when any two character image areas are compressed among a plurality of character image areas included in the image data to be compressed, and the capacity of overhead data added to each of the two character image data On the condition that the total of the character image data size when the area including the two character image areas is compressed and the capacity of the overhead data added to the character image data is smaller than the total of Merging two character image areas as one character image area;
A control method for an image forming apparatus.

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