JP2011120080A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the following problem: power consumption may be increased in an image forming apparatus which includes a plurality of image compressing parts and performs in parallel a plurality of image compressing operations on single image data input for the unit of a predetermined region. <P>SOLUTION: The present invention relates to an image forming apparatus which includes a plurality of image compressing parts and performs in parallel a plurality of image compressing operations on single image data input for the unit of a predetermined processing region. The image forming apparatus includes: a determination means for determining whether or not a size of image compressed data processed in a first image compressing part among the plurality of image compressing parts is smaller than a predetermined value; and a shut-off means for shutting off power supply to a second image compressing part among the plurality of image compressing parts. If it is determined by the determination means that the size of the image compressed data processed in the first image compressing part is smaller than the predetermined value, the shut-off means shuts off power supply to the second image compressing part. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image forming apparatus that performs image compression on input image data and outputs the image data, and more particularly to an image forming apparatus that executes a plurality of image compressions on a single image data in parallel.

  2. Description of the Related Art Conventionally, there has been an image forming apparatus capable of processing not only monochrome but also color image data as the CPU speed increases and the capacity of an IC memory or hard disk increases. However, the image data of the entire page (for example, the paper size is A4, the resolution is 600 dpi, and RGB 8-bit image data per pixel) has a considerably large data amount. Therefore, in general, the image forming apparatus stores the image data in the apparatus in a form in which some compression processing is performed.

  By applying the above image compression, the image forming apparatus can compress (compress) the image data of the entire page and store it, and decompress (decode) the stored image data and execute the necessary processing. Therefore, it is only necessary to have a capacity for storing the entire image data of one page after compression. However, in practice, for example, when it is desired to rotate the image data by 90 degrees, if the image data of one page is compressed in units of pages, the image data cannot be rotated by 90 degrees unless it is once expanded. In order to solve this problem, a technique for dividing one page of image data into rectangular units called tiles (for example, 32 pixels × 32 pixels) has been proposed. Accordingly, if the image data is compressed in units of tiles, necessary processing can be executed after the image compression data is expanded in units of tiles, and a memory capacity for image compression can be saved.

  In recent years, a technique has been proposed in which a plurality of image compression methods are provided in advance and the image compression is selectively performed using an image compression method suitable for the type of image data when the above-described image compression is applied.

  For example, in [Patent Document 1], a lossless compression method is selectively applied to image data in a character area, and an irreversible compression method is selectively applied to image data in a photograph (natural image) area. As a result, it is possible to generate image data with a higher image quality and smaller capacity than before and store it in the device.

  On the other hand, a technique for reducing power consumption by the image compression unit as described above has also been proposed.

  For example, in [Patent Document 2], a difference (= required image processing amount) between the reference image data and the original image data to be compressed next is taken for each block in the image data compression unit, and depending on the magnitude of the difference The power consumption is reduced by raising and lowering the operating frequency of the compression processing element.

  Also, for example, in [Patent Document 3], in the image display unit for image data, the always-displayed part and the blinking-displayed part are stored in the memory, and when the image data does not change for a certain period of time, Power consumption is reduced by cutting off the power supply to all or part of the equipment.

JP 2006-50096 A JP-A-9-9251 JP-A-6-59653

  As described above, if a technique for compressing an image by using a plurality of image compression methods in advance and selectively compressing an image compression method suitable for each image data is used, image data with higher image quality and smaller capacity than before can be obtained. Can be generated. However, a circuit that realizes selection of an image compression method using the above algorithm needs to operate a plurality of image compression processing units in parallel on a single input image data and compare the output results of the image compression processing units. is there. As a result, it is necessary to continue to supply power for executing image compression even to an image compression unit that is not selected as final output data, which increases power consumption in the image processing unit. There is.

  In order to solve the above-described problems, the image forming apparatus of the present invention includes the following configurations and means.

An image forming apparatus (100) that includes a plurality of image compression units (301) and performs a plurality of image compressions on a single image data input in units of a predetermined processing area in parallel.
Of the plurality of image compression units, determination means (406) for determining whether or not the image data size processed by the first image compression unit is smaller than a predetermined value, and among the plurality of image compression units , Comprising a low power consumption mode setting means for reducing the power consumption of the second image compression unit,
The low power consumption mode setting means, when the determination means determines that the image compression data size in the first image compression section (404) is smaller than a predetermined value, the second image compression section (405) is set to a low power consumption mode.

  The present invention is an image forming apparatus that includes a plurality of image compression units and performs a plurality of image compressions in parallel on single image data input in units of predetermined regions. When it is determined that the image compression data size in the first image compression unit is smaller than a predetermined value, the clock supply to the second image compression unit is cut off or the power is turned off to Power consumption in the processing unit can be reduced.

1 is a block diagram illustrating a configuration example of an image forming apparatus according to an embodiment of the present invention. 6 is a flowchart illustrating a control procedure of a scanning unit of the image forming apparatus according to the embodiment of the present invention. 6 is a flowchart illustrating a control procedure of a tile generation unit of the image forming apparatus according to the embodiment of the present invention. 6 is a flowchart illustrating a control procedure of an image compression unit of the image forming apparatus according to the embodiment of the present invention. 6 is a flowchart illustrating a control procedure of an image compression unit of the image forming apparatus according to the embodiment of the present invention. 10 is a flowchart illustrating a control procedure of an image compression unit of an image forming apparatus according to a conventional example. 6 is a flowchart illustrating a control procedure of an image expansion unit of the image forming apparatus according to the embodiment of the present invention. It is a block diagram (conceptual diagram) for explaining the operation of the image compression unit of the image forming apparatus in the embodiment of the conventional example. FIG. 5 is a block diagram (conceptual diagram) illustrating an operation of an image compression unit of the image forming apparatus according to the embodiment of the present invention. FIG. 5 is a block diagram (conceptual diagram) illustrating an operation of an image compression unit of the image forming apparatus according to the embodiment of the present invention. It is a conceptual diagram explaining the image compression processing time of the tile unit of the image forming apparatus in the embodiment of the present invention. 4 is an example of page image data input to the image forming apparatus according to the embodiment of the present invention. It is a conceptual diagram explaining the tile generation process with respect to the page image data input into the image forming apparatus in the embodiment of the present invention.

(Example)
The best mode for carrying out the present invention will be described below with reference to the drawings.

(First embodiment)
A first embodiment of the present invention will be described with reference to FIGS. 1 to 9 and FIGS.

<System configuration>
FIG. 1 is a block diagram showing a configuration example of an image forming apparatus 100 according to the first embodiment of the present invention.

  The image forming apparatus 100 is assumed to be a multifunction peripheral (MFP) capable of realizing a plurality of different functions such as a copy function, a printer function, a scanner function, and a FAX function. The CPU 200, ROM 201, RAM 202, HDD 203, network controller 204, data bus 205, operation display unit 206, scanning units 207 and 208, engine units 209 and 210, and an image processing unit 211 are also included.

  The central processing unit CPU 200 is a control unit that controls transfer of image data and execution of image processing in the image forming apparatus 100. The CPU 200 controls the image forming apparatus 100 by sequentially executing programs stored in advance in the ROM 201.

  The nonvolatile memory ROM 201 is a storage unit that holds a program describing the control unit of the image forming apparatus 100.

  The volatile memory RAM 202 is a storage unit that temporarily stores a program describing the control means and image data in order to realize the functions of the image processing apparatus 100. In particular, the RAM 202 temporarily stores image data when each of the tile generation unit 300, the image compression unit 301, and the image expansion unit 302 in the image processing unit 211 executes image processing. In the embodiment of the present invention, the RAM 202 and the image processing unit 211 are separated and positioned, but the scope of the present invention is not limited to the memory configuration described above. A memory configuration including a storage unit using SRAM or the like may be used.

  The hard disk 203 is a storage unit that stores a program describing control means and image data in order to realize the functions of the image processing apparatus 100. In particular, the hard disk 203 stores the compressed image data compressed by the image compression unit 301. In the embodiment of the present invention, the hard disk 203 is positioned as a storage unit for image data after compression processing. However, the scope of the present invention is not particularly limited to the above-described memory device. Other memory devices may be used.

  A network controller 204 is connected to a network such as the Internet or a LAN, and is a processing unit that transmits and receives image data between the image forming apparatus 100 and an external device.

  The data bus 205 is a set of electrical signal lines that electrically connect the processing units in the image forming apparatus 100. The data bus 205 transfers image data among the processing units of the network controller 204, the scanning units 207 and 208, the engine units 209 and 210, the image processing unit 211, the RAM 202, and the HDD 203 in accordance with a control signal input from the CPU 200. .

  The operation display unit 206 includes a touch panel for inputting user instructions, buttons, switches, a liquid crystal display panel for displaying processing results and selection items from the CPU 200, and the like.

  The scan controller 207 controls the scan device 208 to capture an electrical image signal.

  The scan device 208 is a processing unit that optically reads a document image and converts it into an electrical image signal. The scan device 208 includes a contact image sensor, a reading drive unit, a reading lighting control unit, and the like. When the entire original is scanned by the contact type image sensor driven by the reading drive unit, the scan device 208 controls lighting of the LEDs inside the contact type image sensor by the reading lighting control unit. At the same time, in the scan device 208, a photo sensor inside the contact image sensor optically reads a document image and converts it into an electrical image signal.

  The engine controller 209 takes in an electrical image signal that has been subjected to image processing by the CPU 200 and the image processing unit 211, outputs it to the engine device 210, and controls it.

  The engine device 210 is a processing unit that prints a visible image using toner or ink on recording paper based on an electrical image signal. The engine device 210 is configured by a laser beam printer or an ink jet printer.

  The image processing unit 211 is a processing unit that performs scan system image processing, communication system image processing, and print system image processing. Here, the image processing unit 211 according to the embodiment of the present invention includes at least the processing units of the tile generation unit 300, the image compression unit 301, and the image expansion unit 302. The scan system image processing is image processing for converting image data received from the scan controller 207 into high-definition image data, and includes shading correction, gamma processing, binarization processing, halftone processing, RGB to CMYK color conversion processing, Etc. The print system image processing is image processing for converting the resolution of the image data in accordance with the recording resolution, and executes scaling processing, smoothing correction, density correction, and the like. Communication system image processing is image processing for converting image data according to the capacity and communication performance that can be stored in the image forming apparatus 100, and includes tile generation processing, image compression processing, image expansion processing, resolution conversion, color conversion, Perform conversion processing, etc. Here, the tile generation unit 300 divides one page of image data into rectangular units called tiles (for example, 32 pixels × 32 pixels). The image compression unit 301 includes a plurality of image compression methods in advance for the tile-unit image data divided by the tile generation unit 300, and selectively applies an image compression method suitable for each image data. . Specifically, first, image data in units of tiles is compressed by a lossless compression method. When the reversible compressed image data size is smaller than a predetermined value, the reversible compressed image data is output. When the size of the image data compressed by the lossless compression method is larger than a predetermined value, the image data in tile units is compressed by the lossy compression method, and the data of the lossless compressed image image data and the lossy compressed image image data is compressed. The smaller size is output. The image expansion unit 302 includes a plurality of image expansion methods for the tile-unit image data compressed by the image compression unit 301 in advance, and corresponds to the image compression method selectively applied by the image compression unit 301. An image compression method is applied to generate uncompressed image data.

<Device operation>
A control procedure of the image forming apparatus 100 according to the embodiment of the present invention will be described with reference to FIGS. 2 to 9 and FIGS. 11 to 12.

  FIG. 2 is a flowchart illustrating a control procedure of the scan controller 207 of the image forming apparatus 100 according to the embodiment of the present invention. FIG. 4 is an example of page image data input to the image forming apparatus 100 according to the embodiment of the present invention.

(S100)
In the image forming apparatus 100, the scan controller 207 and the scan device 208 read page-unit image data as in the example shown in FIG. Here, the scanning device 208 sequentially reads pixel data pixel by pixel in the main scanning width X direction, and after reading one line in the main scanning width X direction, continues to pixel data of the next line in the sub scanning width Y direction. Are sequentially read pixel by pixel.

(S101)
In the image forming apparatus 100, the scan controller 207 detects whether or not image data for a main scanning width X × tile width (for example, 32 pixels) called a band shown in FIG. If image data for one band is held on the RAM 202 (Yes), the process proceeds to step S102. If not (No), the process proceeds to step S100.

(S102)
The image forming apparatus 100 notifies the tile generation unit 300 electrically connected via the data bus 205 from the scan controller 207 that the image data for one band is held on the RAM 202.

(S103)
In the image forming apparatus 100, is the scan controller 207 notified from the tile generation unit 300 electrically connected via the data bus 205 that the tile generation processing of the image data for one band on the RAM 202 has been completed. Detect whether or not. Here, if the tile generation processing of the image data for one band on the RAM 202 is completed (Yes), the process proceeds to step S104, and if not completed (No), the process proceeds to step S103 again.

(S104)
The image forming apparatus 100 determines in the scan controller 207 whether or not reading of all pixel data of image data of page units as in the example shown in FIG. 12, that is, main scanning width X × sub-scanning width Y has been completed. Detect. Here, if reading of all pixel data of the main scanning width X × sub-scanning width Y is completed (Yes), the scanning operation is terminated, and if not completed (No), the process proceeds to step S100 and the scanning operation is performed. Continue.

  FIG. 3 is a flowchart illustrating a control procedure of the tile generation unit 300 of the image forming apparatus 100 according to the embodiment of the present invention. FIG. 13 is a conceptual diagram illustrating tile generation processing for page image data input to the image forming apparatus 100 according to the embodiment of the present invention.

(S200)
The image forming apparatus 100 determines whether or not the tile generation unit 300 has been notified by the scan controller 207 that is electrically connected via the data bus 206 that the image data for one band has been retained on the RAM 202. Detect. If image data for one band is held on the RAM 202 (Yes), the process proceeds to step S201. If not (No), the process proceeds to step S200 again.

(S201)
In the tile forming unit 300, the tile generation unit 300 converts pixel data for each tile (for example, 32 pixels × 32 pixels) pixel by pixel from image data for one band on the RAM 202 as in the example illustrated in FIG. 13. Read sequentially, transfer to RAM 202 and hold. Here, the tile generation unit 300 sequentially reads pixel data in the main scanning width X direction in units of tiles, as indicated by arrows in FIG. 13, and after reading the tile width in the main scanning width X direction, Subsequently, the pixel data of the next line in the sub-scanning width Y direction is sequentially read pixel by pixel.

(S202)
In the image forming apparatus 100, in the tile generation unit 300, image data corresponding to a tile width in the main scanning width X direction × tile width in the sub scanning direction (for example, 32 pixels × 32 pixels) called a tile illustrated in FIG. Detect whether it is held on. If one tile of image data is held on the RAM 202 (Yes), the process proceeds to step S203. If not (No), the process proceeds to step S201.

(S203)
In the tile forming unit 300, the image forming apparatus 100 adds position information (coordinates) of the tile image data in the page image data as header information of the tile image data, and writes it on the RAM 202. Here, for the position information (coordinates) of the tile image data, for example, when it is desired to rotate the image data by 90 degrees, each of the tile image data is rotated by 90 degrees and each position of the tile image data is appropriately changed. This information is necessary for reading.

(S204)
The image forming apparatus 100 detects whether or not the tile generation unit 300 has acquired all the image data for each tile from the image data for one band on the RAM 202 as in the example illustrated in FIG. 13. If all the tile-unit image data has been acquired (Yes), the process proceeds to step S205. If not acquired (No), the process proceeds to step S201.

(S205)
The image forming apparatus 100 notifies the tile generation unit 300 to the scan controller 207 that is electrically connected via the data bus 205 that the tile generation processing of image data for one band on the RAM 202 has been completed. To do.

(S206)
In the image forming apparatus 100, has the tile generation unit 300 completed tile generation processing for all pixel data of page data as in the example illustrated in FIG. 12, that is, image data of main scanning width X × sub-scanning width Y? Detect whether or not. Here, if the tile generation process of all pixel data of main scanning width X × sub-scanning width Y is completed (Yes), the tile generation process is ended. If not completed (No), the process proceeds to step S200. To continue the tile generation process.

  FIG. 6 is a flowchart illustrating a control procedure of the image compression unit 300 of the image forming apparatus 100 according to the conventional embodiment. FIG. 8 is a block diagram (conceptual diagram) for explaining the operation of the image compression unit of the image forming apparatus 100 in the embodiment of the conventional example.

(S400)
In the image forming apparatus 100, the image compression unit 301 reads tile image data via the input data control unit 400 illustrated in FIG. 8 and stores the tile image data in the image buffers 401a to 401b.

(S401)
The image forming apparatus 100 includes a plurality of image compression methods 402 to 403 illustrated in FIG. 8 in the image compression unit 301, and applies the plurality of image compression methods simultaneously in parallel. For example, the reversible compression processing unit 402 and the irreversible compression processing unit 403 are simultaneously applied in parallel to the tile-unit image data held in the image buffers 401a to 401b, and the image data after the compression processing is stored in the image buffers 401c to 401c. 401d.

(S402)
The image forming apparatus 100 compares the volumes of the compressed image data held in the image buffers 401c to 401d by the output data selection unit shown in FIG. Adopt it and discard the one with more capacity. That is, for example, if the capacity of the image data after the compression processing by the lossless compression processing unit 404 is 550 bytes and the capacity of the image data after the compression processing by the lossy compression processing unit 405 is 450 bytes, the lossy compression processing unit 405 The output of is adopted. Here, the image compression unit 301 stores the selected image data after compression processing in the hard disk HDD 203 via the output data control unit 408.

(S403)
In the image forming apparatus 100, has the image compression unit 301 completed image compression processing for all pixel data of page units as in the example illustrated in FIG. 12, that is, image data of main scanning width X × sub-scanning width Y? Detect whether or not. Here, if the image compression processing of all the pixel data of the main scanning width X × sub-scanning width Y is completed (Yes), the image compression processing is completed. If not completed (No), the process proceeds to step S400. To continue the image compression process.

  FIG. 4 is a flowchart illustrating a control procedure of the image compression unit 300 of the image forming apparatus 100 according to the embodiment of the present invention. FIG. 9 is a block diagram (conceptual diagram) for explaining the operation of the image compression unit 300 of the image forming apparatus 100 according to the embodiment of the present invention.

(S300)
In the image forming apparatus 100, the image compression unit 301 reads tile image data via the input data control unit 400 illustrated in FIG. 9 and stores the tile image data in the image buffers 401a to 401b.

(S301)
In the image forming apparatus 100, the operation circuit selection unit 402 shown in FIG. 9 in the image compression unit 301 inputs the tile image data of the image buffer 401a to the lossless compression processing unit (lossless image encoder).

(S302)
The image forming apparatus 100 determines whether or not the compressed image data size of the image buffer 401c is smaller than a predetermined value by the determination unit illustrated in FIG. 9 in the image compression unit 301. When it is determined that the compressed image data size of the image buffer 401c is smaller than a predetermined value, the process proceeds to step S306. When it is determined that the compressed image data size of the image buffer 401c is larger than a predetermined value, the process proceeds to step S304.

(S304)
The power supply to the irreversible compression processing unit (irreversible image encoder) 405 is cut off.

(S305)
In the image forming apparatus 100, the operation circuit selection unit 402 shown in FIG. 9 in the image compression unit 301 inputs tile image data of the image buffer 401b to the irreversible compression processing unit (irreversible image encoder).

(S306)
In the image forming apparatus 100, the output data selection unit 407 shown in FIG. 9 in the image compression unit 302 compares the volume of the compressed image data held in the image buffers 401d to 401e, and the smaller one is stored. Selectively adopt and discard the one with more capacity. However, when effective image data is not generated as image data after compression processing due to the interruption of power supply, this is not selected. For example, if the capacity of the image data after the compression processing by the reversible compression processing unit 404 is 250 bytes, but no valid image data is generated as the image data after the compression processing by the irreversible compression processing unit 405, The output of the lossless compression processing unit 404 is employed. Similarly, for example, if the capacity of the image data after the compression processing by the lossless compression processing unit 404 is 550 bytes and the capacity of the image data after the compression processing by the lossy compression processing unit 405 is 450 bytes, the lossy compression processing unit Adopt 405 output. The above selection is the same for other tile image data. Here, the image compression unit 302 stores the selected image data after compression processing in the hard disk HDD 203 via the output data control unit 408.

(S307)
In the image forming apparatus 100, the image compression unit 302 performs image compression processing of all pixel data of image data of page units, that is, main scanning width X × sub-scanning width Y as in the examples illustrated in FIGS. Detect whether or not it is finished. Here, if the image compression processing of all the pixel data of the main scanning width X × sub-scanning width Y is completed (Yes), the image compression processing is completed. If not completed (No), the process proceeds to step S300. To continue the image compression process.

  FIG. 7 is a flowchart illustrating a control procedure of the image expansion unit 303 of the image forming apparatus 100 according to the embodiment of the present invention.

(S500)
In the image forming apparatus 100, the image expansion unit 302 reads the tile image data after the compression processing, and holds it in an image buffer (not shown).

(S501)
The image forming apparatus 100 includes a plurality of image expansion methods corresponding to inverse conversion of the plurality of image compression methods 404 to 405 illustrated in FIG. 8 in the image expansion unit 302, and any one of the plurality of image expansion methods. Is applied and the decompressed image data is held in the image buffer. For example, an irreversible decompression processing unit (irreversible image decoder) is applied to tile image data after compression processing compressed using irreversible compression processing (irreversible encoder). Similarly, for example, a reversible decompression processing unit (reversible image decoder) is applied to tile image data after compression processing compressed using a reversible compression processing (reversible encoder).

(S502)
In the image forming apparatus 100, the image compression unit 301 stores the compressed image data held in the image buffer (not shown) in the hard disk HDD 203.

(S503)
In the image forming apparatus 100, the image compression unit 301 performs image expansion processing for all pixel data of page data, that is, image data of main scanning width X × sub-scanning width Y as in the examples illustrated in FIGS. Detect whether or not it is finished. Here, if the image expansion process of all the pixel data of the main scanning width X × sub-scanning width Y is completed (Yes), the image expansion process is ended. If not completed (No), the process proceeds to step S500. To continue the image expansion process.

  FIG. 11 is a conceptual diagram illustrating tile-based image compression processing time by a plurality of image compression units 301 in the image forming apparatus 100 in the conventional embodiment and the embodiment of the present invention. In the conventional embodiment, the reversible compression processing unit (reversible image encoder) 402 and the irreversible compression processing unit (irreversible image encoder) 403 are simultaneously performed in parallel on the tile-unit image data held in the image buffers 401a to 401b. Apply. On the other hand, in the embodiment of the present invention, first, the lossless compression processing unit 402 is applied to the image data held in the image buffer 401a. Next, when the first determination unit 406 determines that the compressed image data is larger than the specified value, the irreversible compression processing unit 403 is applied to the image data held in the image buffer 401b. Therefore, the latency per tile is smaller in the conventional embodiment. However, since a plurality of tiles are pipelined in actual use, as shown in FIG. 11, the throughput is equivalent to that of the conventional embodiment and the embodiment of the present invention.

  In the embodiment of the present invention, a plurality of image compression units 301 have been described. However, the scope of the present invention is not particularly limited to the above example. That is, the same applies to different image processing other than image compression as long as the image processing unit operates a plurality of image processes simultaneously and in parallel on a single image data.

  In the embodiment of the present invention, it has been described that the power supply is shut off using the shut-off means 403 included in the operation circuit selection unit 409. However, the claims of the present invention particularly relate to the means for realizing the shut-off. It doesn't matter. As an implementation method, for example, either one of the operation clock signals electrically connected to the reversible image compression unit 404 and the irreversible image compression unit 405 in the image compression unit 301 from the power supply unit is masked. Then, a method of stopping the clock supply may be used. As another implementation method, for example, the power supply system itself supplied from the power supply unit to the reversible image compression unit 404 and the irreversible image compression unit 405 in the image compression unit 301 is separated in advance. A method of stopping either one of the power supply systems may be used.

(Second Embodiment)
A second embodiment of the present invention will be described with reference to FIG.

<System configuration>
FIG. 10 shows an image compression processing unit according to the second embodiment of the present invention. In the second embodiment related to the present invention, the system configuration of the image forming apparatus other than the image compression processing unit is the same as that of the first embodiment.

<Device operation>
A control procedure of the image forming apparatus 100 according to the embodiment of the present invention will be described with reference to FIGS.

  FIG. 5 is a flowchart illustrating a control procedure of the image compression unit 300 of the image forming apparatus 100 according to the embodiment of the present invention. FIG. 10 is a block diagram (conceptual diagram) for explaining the operation of the image compression unit 300 of the image forming apparatus 100 according to the embodiment of the present invention.

(S300)
In the image forming apparatus 100, the image compression unit 301 reads tile image data via the input data control unit 400 illustrated in FIG. 9 and stores the tile image data in the image buffers 401a to 401b.

(S301)
In the image forming apparatus 100, the operation circuit selection unit 402 shown in FIG. 9 in the image compression unit 301 inputs the tile image data of the image buffer 401a to the lossless compression processing unit (lossless image encoder).

(S302)
The image forming apparatus 100 determines whether or not the compressed image data size of the image buffer 401c is smaller than a predetermined value by the determination unit illustrated in FIG. 9 in the image compression unit 301. When it is determined that the compressed image data size of the image buffer 401c is smaller than a predetermined value, the process proceeds to step S306. When it is determined that the compressed image data size of the image buffer 401c is larger than a predetermined value, the process proceeds to step S304.

(S304)
The power supply to the irreversible compression processing unit (irreversible image encoder) 405 is cut off.

(S306)
The image forming apparatus 100 outputs the image data after the lossless compression process held in the image buffer 401d by the output data selection unit 407 shown in FIG. Here, the image compression unit 302 stores the image data after the lossless compression process in the hard disk HDD 203 via the output data control unit 408.

(S305)
In the image forming apparatus 100, the operation circuit selection unit 402 illustrated in FIG. 10 in the image compression unit 301 inputs the tile image data of the image buffer 401b to the irreversible compression processing unit (irreversible image encoder).

(S308)
The image forming apparatus 100 outputs the image data after the irreversible compression processing held in the image buffer 401e by the output data selection unit 407 shown in FIG. Here, the image compression unit 302 stores the image data after the irreversible compression processing in the hard disk HDD 203 via the output data control unit 408.

(S307)
In the image forming apparatus 100, the image compression unit 302 performs image compression processing of all pixel data of image data of page units, that is, main scanning width X × sub-scanning width Y as in the examples illustrated in FIGS. Detect whether or not it is finished. Here, if the image compression processing of all the pixel data of the main scanning width X × sub-scanning width Y is completed (Yes), the image compression processing is completed. If not completed (No), the process proceeds to step S300. To continue the image compression process.

100 Image forming apparatus 101 Network 200 CPU
201 ROM
202 RAM
203 Hard disk (HDD)
204 Network Controller 205 Data Bus 206 Operation Display Unit 207 Scan Controller 208 Scan Device 209 Engine Controller 210 Engine Device 211 Image Processing Unit 300 Tile Generation Unit 301 Image Compression Unit 302 Image Expansion Unit 400 Input Data Control Units 401a to 401d Image Data Buffer 402 Operation circuit selection unit 403 Blocking unit 404 Image compression processing unit (reversible image encoder)
405 Image compression processing unit (irreversible image encoder)
406 Determination unit 407 Output data selection unit 408 Output data control unit

Claims (6)

An image forming apparatus (100) that includes a plurality of image compression units (301) and performs a plurality of image compressions on a single image data input in units of a predetermined processing area in parallel.
Of the plurality of image compression units, determination means (406) for determining whether or not the image data size processed by the first image compression unit is smaller than a predetermined value, and among the plurality of image compression units, A low power consumption mode setting means for reducing power consumption of the second image compression unit;
When the determination unit determines that the image compression data size in the first image compression unit (404) is smaller than a predetermined value, the blocking unit (403) is the first image compression unit. The second image compression unit (405) is set to the low power consumption mode using the compressed image data as output data. When it is determined by the determination means that the image compression data size in the first image compression unit is larger than a predetermined value, the second image compression unit is applied to single input image data. An image forming apparatus that performs image compression using The image processing apparatus according to claim 1,
An output data selection unit (407) for selecting a smaller one of the plurality of image data;
When the determination means determines that the image compression data size in the first image compression unit is larger than a predetermined value, the output data selection unit is processed by the first image compression unit An image forming apparatus that selects and outputs a smaller one of an image compression data size and an image compression data size processed by the second image compression unit. The image processing apparatus according to claim 1,
Outputting the compressed image data processed by the second image compression unit when the determination unit determines that the compressed image data size in the first image compression unit is larger than a predetermined value; An image forming apparatus. The image processing apparatus according to claim 1,
An image forming apparatus, wherein the first image compression unit (404) performs a reversible compression process, and the second image compression unit (405) performs a lossy compression process. The image processing apparatus according to claim 1,
In the low power consumption mode, the power consumption is reduced by stopping clock supply to the image compression unit of the second image compression unit. The image processing apparatus according to claim 1,
In the power consumption mode, the power consumption is reduced by switching a power source separated in advance corresponding to the image compression unit of the second image compression unit to an off state. .

Images