JP2011250151A - Memory control device and image formation device therewith - Google Patents

Abstract

PROBLEM TO BE SOLVED: To aim for an effective use of a page memory to the utmost limit and prevent an overwriting of image data, forbidden for the overwriting due to a low compressibility of the image data.SOLUTION: A memory control device is equipped with: an input part; a band dividing part which divides a image data into bands; a compression processing part; a decompression processing part; an image processing part which runs image processing of the image data; a page memory which executes an entry for each of the bands in band sequence from a beginning point of an address in a given direction and reuses a memory by returning to the beginning point when the entry processing reaches to a final block in the entry direction of the page memory; and a memory control part which controls an output from the page memory or an entry to the page memory, evaluates an idle capacity of the final block of the page memory, and orders the return to the beginning point of the address and an entry in case the idle capacity is smaller than a post-compression data size of a band to be entered.

Description

  The present invention relates to a memory control device including a page memory. The present invention also relates to an image forming apparatus such as a multifunction machine, a copying machine, a printer, and a FAX apparatus provided with a memory control device.

  For example, an image forming apparatus such as a multifunction peripheral is provided with an image processing unit that performs various types of image processing on read image data and input image data. In order to store the image data before being processed by the image processing unit and the image data after being processed, a page memory for storing at least one page of image data may be mounted. Here, if the capacity of the page memory mounted on the image forming apparatus is small, the manufacturing cost of the image forming apparatus can be reduced. Therefore, Patent Document 1 discloses an image recording apparatus that uses a single page memory and supports various image recording modes.

  Specifically, in Patent Document 1, in an image recording apparatus that records and outputs image data developed in a page memory by an image recording unit, a plurality of image data input units respectively corresponding to a plurality of image recording modes, Mode switching setting means for setting to any one of the image recording modes, the page memory is shared by a plurality of image recording modes, and is set by the mode switching setting means of the plurality of image recording modes. However, there is described an image recording apparatus that records and outputs recording target image data obtained from an image data input unit corresponding to a mode by an image recording unit. With this configuration, a page memory is shared for image recording in each image recording mode, and it is not necessary to provide a page memory for each image recording mode, thereby reducing the cost of the apparatus. (See Patent Document 1: Claim 1, paragraph [0082], etc.).

JP2002-142088

  A page memory such as an image forming apparatus may temporarily store read image data, output image data for image processing, and store image data after image processing such as density conversion, zoom, and filter processing again. In other words, the page memory sometimes repeats input (storage) → output → re-input (storage) of image data of the same page. For example, image data for one page is divided into a plurality of bands, output from the page memory in band units, and re-input to the page memory.

  The page memory is, for example, a capacity with some margin for the size of image data for one page. Therefore, when image data of the same page is input (stored) → output → re-input (stored) is repeated, image data after image processing may be overwritten in the area of image data already output from the page memory. . In other words, the page memory may be reused.

  Here, from the viewpoint of reducing the capacity of the page memory and improving the processing speed, the image data may be stored in the page memory after performing the compression process. For example, image data that has been subjected to image processing by the image processing unit is compressed and stored in the page memory. Since image processing cannot be performed in the compressed state, the image data output from the page memory is decompressed before being subjected to image processing in the image processing unit.

  Here, when the image processing is performed in the image processing unit, the compression rate of the image data may deteriorate. For example, the image data is compressed using an algorithm such as a Huffman code. However, if the pixel value (density value) of each pixel of the image data is changed by image processing, the compression rate may deteriorate. Then, for example, for the same band, the data size after compression after image processing is larger than that before image processing.

  Therefore, when the band output from the page memory is stored again in the page memory, the image data (band) after the image processing is the image data (band) that has not been output from the page memory, in other words, waiting for image processing. There is a problem that the band may be overwritten. If overwritten, for example, generation of abnormal image data or printing of an abnormal image occurs.

  Here, when viewing the image recording apparatus described in Patent Document 1, it may certainly be possible to reduce the manufacturing cost by eliminating the need to separately provide a page memory for each image recording mode. However, the invention described in Patent Document 1 does not store the image data in the page memory after performing the compression process, and there is no description to that effect. Therefore, to realize the invention practically, a large-capacity page memory and a high-speed memory are required, and the manufacturing cost reduction is not always achieved. In addition, the above-mentioned problem may be caused due to the deterioration of the compression rate due to image processing, and the above problem cannot be solved.

  In view of the above problems, the present invention aims to effectively utilize the page memory to the limit and reduces the compression rate of the image data subjected to image processing. The challenge is to prevent overwriting.

  In order to achieve the above object, a memory control device according to claim 1 includes an input unit for inputting image data, a banding unit for dividing input image data for one page into a plurality of bands, and an image A compression processing unit that performs data compression processing, a decompression processing unit that decompresses compressed image data, an image processing unit that performs image processing of image data decompressed by the decompression processing unit, and a plurality of blocks The image data is divided and output to the decompression processing unit in units of bands, and is image data input to the input unit or image data processed by the image processing unit, wherein the compression processing unit compresses the image data. The received image data is received and stored in band units, and written in the band order in the band units in a fixed direction from the start point of the address, leading to the final block in the write direction. And a page memory that recycles the memory by returning to the start point, and controlling the output and writing from the page memory, and the free capacity of the final block is smaller than the data size after compression of the band to be written A memory control unit that returns to the start point and writes data when the free capacity of the final block is smaller than the compressed data size of the band to be written. It was.

  According to this configuration, when the last block in the page memory writing direction is reached and the free capacity of the last block is smaller than the data size after compression of the band to be written, the writing is performed by returning to the head point. As a result, when writing to the page memory in cycles (using the page memory), the capacity of the page memory is used to the limit, and the page memory can be used effectively.

  The invention according to claim 2 is the invention according to claim 1, wherein the memory control unit attempts to write the band after compression in the last block of the page memory, and can write all data of the band. Whether or not the free capacity of the last block is smaller than the data size of the band to be written is determined.

  According to this configuration, in the last block in the page memory writing direction, an attempt is made to write the compressed band, and depending on whether or not all the band data can be written, the free capacity of the last block is the data size of the band to be written. Or less is determined. Since it is actually tried in this way, it is clearly confirmed whether or not a band after image processing compressed in the final block can be written. Therefore, the page memory can be used reliably up to the capacity limit, and the page memory can be effectively used.

  According to a third aspect of the present invention, in the first or second aspect of the invention, the image processing unit has a work memory as a work area for performing image processing, and the image processing unit performs image processing. Therefore, when the page memory outputs image data to the decompression processing unit, the image processing is performed in the image processing unit, and the band after compression processing is stored again in the page memory, the page memory is The storage area of the band portion output to the decompression processing section is treated as a free capacity, and the memory control section has a free capacity of the page memory smaller than the compressed data size of the band to be written. If it is smaller, the page memory is made to output image data to the decompression processing unit in units of bands while waiting for writing of the bands. After the free space is secured, it was decided to write the band that was allowed to stand in the page memory.

  According to this configuration, when the free space of the page memory is smaller than the compressed data size of the band to be written, the free space of the page memory for the data size after the compression of the band to be written is ensured. While waiting for the writing of the band, the page memory is caused to output the image data to the decompression processing unit in band units, and after securing, the band that has been waiting is written to the page memory. As a result, the free band of the page memory is secured, and the compressed band after image processing is written. Accordingly, it is possible to eliminate overwriting of a band after image processing to a band that has not yet been output from the page memory for image processing (a band waiting for image processing).

  According to a fourth aspect of the present invention, in the first to third aspects of the present invention, the memory control unit waits for writing of the band, and stores the page memory in the band unit until the work memory is completely filled. Even if the image data is output to the decompression processing unit, if the free space of the page memory corresponding to the data size after compression of the band to be written cannot be secured, the occurrence of an error is recognized and the error occurrence is notified. It was decided to have a notification unit.

  According to this configuration, even if image data is output to the decompression processing unit in band units in the page memory until the work memory is filled up while waiting for writing of the band, the compressed data size of the band to be written The occurrence of an error is recognized when there is not enough free space in the page memory. Accordingly, it is possible to notify the user that abnormal image data is generated. In addition, the user can be informed that even if the work memory is used to the limit, overwriting of the band after the compressed image processing to the band not output from the page memory will occur. It is possible to make the user recognize the necessity of countermeasures such as change of the user.

  According to a fifth aspect of the present invention, in the first to fifth aspects of the invention, the image processing unit performs at least zoom processing, density conversion processing, and filter processing.

  According to this configuration, the image processing unit performs at least zoom processing, density conversion processing, and filter processing. For example, in image processing involving conversion of the pixel value of each pixel in these image data, the band compression rate may deteriorate. However, even if it has an image processing unit that performs these image processing, the band of the band after compressed image processing to the band that has not yet been output from the page memory for image processing (the band waiting for image processing) Overwriting can be prevented.

  An image forming apparatus according to a sixth aspect includes the memory control apparatus according to any one of the first to fifth aspects.

  According to this configuration, the memory control device prevents overwriting of a band after compressed image processing to a band that has not yet been output from the page memory for image processing (band waiting for image processing). It is possible to provide an image forming apparatus that does not generate certain image data and does not print based on abnormal image data.

  According to the present invention, the storage area is sufficiently effectively used when using the page memory. In addition, the work memory is used to secure as much free space as possible in the page memory. Therefore, it is possible to avoid overwriting the image data in the page memory in which an abnormal image is generated due to deterioration in the compression rate of the image data subjected to image processing.

1 is a schematic cross-sectional view illustrating a schematic configuration of a multifunction machine according to an embodiment. FIG. 3 is an enlarged cross-sectional view of one image forming unit according to the embodiment. 1 is a block diagram illustrating an example of a hardware configuration of a multifunction machine according to an embodiment. It is a block diagram which shows an example of the flow of the input image data in the memory control apparatus which concerns on embodiment. It is explanatory drawing which shows an example of the division | segmentation of the image data by the banding part which concerns on embodiment. It is a block diagram which shows the outline | summary of the image process of the flow of the image data using the page memory which concerns on embodiment. It is explanatory drawing regarding use of the storage area of the page memory which concerns on embodiment, and operation | movement, (a) shows a storage area when all the bands of the image data for 1 page are memorize | stored, (b) is 1 An example of the band process is shown, (c) shows an example of the second band process, and (d) shows an example of the third band process. It is explanatory drawing regarding use of the storage area of the page memory which concerns on embodiment, and operation | movement, (a) shows an example of the process of 4th band, and memorize | stores when all the bands of the image data for 1 page were memorize | stored (B) shows an example of overwriting of the sixth band by the fifth band, (c) shows an example of processing for waiting for writing until the free space becomes sufficient, and (d) shows 5 An example of processing of the band is shown. It is a flowchart which shows an example of the process of the image data in the memory control apparatus which concerns on embodiment.

  Hereinafter, an embodiment of the present invention will be described based on FIGS. 1 to 9 by taking an electrophotographic tandem type color multifunction peripheral 400 (corresponding to an image forming apparatus) including the memory control apparatus 100 according to the present invention as an example. To do. However, each element such as the configuration and arrangement described in the present embodiment is merely an illustrative example without limiting the scope of the invention.

(Schematic configuration of image forming apparatus)
First, an outline of a multifunction machine 400 according to an embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a schematic cross-sectional view showing a schematic configuration of a multifunction machine 400 according to an embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view of one image forming unit 51 according to the embodiment of the present invention.

  As shown in FIG. 1, the multifunction machine 400 according to the present embodiment is provided with an operation panel 1 (shown by a broken line in FIG. 1, corresponding to a notification unit) at an upper front portion. The operation panel 1 also includes various keys such as a liquid crystal display unit 11 and a start key 12, and accepts display of the state of the multi-function device 400 (for example, error occurrence and mode) and various inputs from the user. The multifunction machine 400 includes an image reading unit 2 (corresponding to an input unit) and a document conveying device 3 in the upper part, and a sheet feeding unit 4a, a conveyance path 4b, an image forming unit 5, an intermediate transfer unit 6a, a fixing unit in the main body. Part 6b and the like.

  The document conveying device 3 automatically and continuously reads the documents stacked on the document tray 31 one by one by rotating the plurality of rollers during document copying. It is conveyed toward the contact glass 21). The image reading unit 2 reads a document and generates image data of the document. On the upper surface of the image reading unit 2, a feed reading contact glass 21 and a placement reading contact glass 22 are provided. In the image reading unit 2, an exposure lamp, a mirror, a lens, and an image sensor (for example, a CCD, An optical system member (not shown) such as FIG. 4) is provided.

  The image reading unit 2 uses these optical system members to irradiate light on a document transported by the document transport device 3 or a document placed on a contact glass, and receives an image sensor reflected by the document. A / D conversion is performed on the output value of each pixel to generate image data. The multi-function device 400 can perform printing based on the image data obtained by reading (copy function). Note that the document conveying device 3 is provided with a rotation fulcrum at the back side of FIG. 1 and can be lifted. After the document is placed on the placement reading contact glass 22, the document conveying device 3 can hold the document. .

  The paper feed unit 4a accommodates various sizes of paper (sheets) such as copy paper and label paper, for example, toward the intermediate transfer unit 6a. The paper feed unit 4a feeds paper one by one to the transport path 4b by a paper feed roller 41 that is rotated by a drive mechanism (not shown) such as a motor. The conveyance path 4b conveys the sheet in the multifunction peripheral 400 and guides the sheet supplied from the sheet feeding unit 4a to the discharge tray 42 through the intermediate transfer unit 6a and the fixing unit 6b. In the transport path 4b, there are a pair of transport rollers 43, a guide 44, and a pair of registration rollers 45 for waiting the transported paper in front of the intermediate transfer section 6a and feeding the paper in time with toner image formation in the image forming section 5. Provided.

  Further, as shown in FIG. 1, the multi-function device 400 includes an image forming unit 5 as a part for forming a toner image based on image data of an image to be formed. Specifically, the image forming unit 5 starts from the left side of FIG. 1 with an image forming unit 51Bk that forms a black image, an image forming unit 51Y that forms a yellow image, and an image forming unit 51C that forms a cyan image. An image forming unit 51M for forming a magenta image, an exposure device 52, and the like.

  Here, the image forming units 51Bk to 51M will be described in detail with reference to FIG. Each of the image forming units 51Bk to 51M is basically the same configuration and can be described in the same manner, except that the color of the toner image to be formed is different. Therefore, only one image forming unit 51 is shown in FIG. 2, and in the following description, the symbols for identifying the colors of the respective image forming units 51, Bk, Y, C, and M, are unless otherwise specified. Omitted.

  First, each photosensitive drum 53 (corresponding to an exchange unit) carries a toner image on its peripheral surface, and is driven to rotate counterclockwise at a predetermined process speed by a driving device (not shown). Each charging device 54 charges the photosensitive drum 53 to a constant potential. The charging device 54 may be one using a corona discharge type or a brush. The exposure device 52 below each image forming unit 51 converts an input color-separated image signal into an optical signal by a laser output unit (not shown), and laser light (converted optical signal). 4) can be output for four colors, and the photosensitive drum 53 after scanning is subjected to scanning exposure to form an electrostatic latent image.

  Each developing device 55 stores a developer (not shown) including toner (the developing device 55 of the image forming unit 51Bk is black, the developing device 55 of the image forming unit 51Y is yellow, and the developing device 55 of the image forming unit 51C is The developing device 55 of the cyan image forming unit 51M stores magenta developer). Each developing device 55 faces the photoconductive drum 53 and supplies toner to the photoconductive drum 53 during image formation.

  The toner image forming process will be described. An electrostatic latent image is formed by exposing the charged photosensitive drum 53 with laser light from the exposure device 52 in accordance with image data. The charged toner flies from the developing device 55, adheres to the surface of the photosensitive drum 53 according to the magnitude of the potential provided by exposure, and the electrostatic latent image is developed as a toner image. Each cleaning device 56 cleans the photosensitive drum 53.

  Returning to FIG. 1, the intermediate transfer unit 6 a receives the primary transfer of the toner image from the photosensitive drum 53 and performs the secondary transfer on the sheet. The intermediate transfer unit 6a is attached to one of the photosensitive drums 53, and each primary transfer roller 61 (a total of four, 61Bk to 61M), an intermediate transfer belt 62, a driving roller 63, and driven rollers 64 to 66 are provided. It includes a secondary transfer roller 67, a belt cleaning device 68, and the like. Each primary transfer roller 61 is in contact with the intermediate transfer belt 62 so as to sandwich each photosensitive drum 53 and the endless intermediate transfer belt 62. Then, a transfer voltage on which alternating current and direct current are superimposed is applied to each primary transfer roller 61 and timed, and the toner images are sequentially transferred onto the intermediate transfer belt 62 without being shifted.

  The intermediate transfer belt 62 is stretched around a primary transfer roller 61, a driving roller 63, and driven rollers 64 to 66, and is rotated by a driving roller 63 connected to a driving mechanism (not shown) such as a motor. Circulate clockwise. The driving roller 63 sandwiches the secondary transfer roller 67 and the intermediate transfer belt 62. The superimposed toner images are transferred from the intermediate transfer belt 62 to a sheet by a secondary transfer roller 67 to which a predetermined voltage is applied. The residual toner on the intermediate transfer belt 62 after the secondary transfer is removed and collected by the belt cleaning device 68.

  The fixing unit 6b is disposed on the downstream side in the paper conveyance direction, and fixes the toner image secondarily transferred to the paper by heating and pressing. The fixing unit 6b is mainly composed of a heating roller 69H containing a heat source and a pressure roller 69P pressed against the heating roller 69H, and a nip is formed between the two rollers. Then, the paper on which the toner image is transferred passes through the nip and is heated and pressurized, and as a result, the toner image is fixed on the paper. The fixed sheet is discharged to the discharge tray 42 to complete the image formation.

(Hardware configuration of MFP 400)
Next, a hardware configuration of the multifunction machine 400 according to the embodiment of the present invention will be described with reference to FIG. FIG. 3 is a block diagram illustrating an example of a hardware configuration of the multifunction machine 400 according to the embodiment of the present invention.

  As shown in FIG. 3, the multifunction machine 400 according to the present embodiment includes a control unit 7 on an internal control board. The control unit 7 controls the overall operation of the apparatus and controls each unit of the multifunction machine 400. The control unit 7 includes, for example, a CPU 70 as a central processing unit and a memory control unit 8. The CPU 70 controls the multifunction peripheral 400 using data and programs in a ROM 71, RAM 72, and HDD 73 described later.

  The memory control unit 8 is a memory controller that controls output (reading) and input (writing) from a page memory 9 described later. The page memory 9 is effectively used under the control of the memory control unit 8. In FIG. 3, the memory control unit 8 is provided in the control unit 7, but may be provided outside the control unit 7, and the installation position is not particularly limited.

  And ROM71 and RAM72 are connected so that communication with the control part 7 and a bus | bath etc. is possible. The ROM 71 is a non-volatile memory that retains stored contents even when the power is turned off. The ROM 71 stores programs executed by the CPU 70 for control, startup programs, and fixed data for various controls such as various parameters unique to the apparatus. The RAM 72 temporarily stores programs executed by the CPU 70 during control and various data.

  The controller 7 is communicably connected to an engine controller 50 that actually controls paper conveyance and printing. The control unit 7 gives an instruction to the engine control unit 50. In response to this instruction, the engine control unit 50 rotates various rotating bodies (such as the conveyance roller pair 43 and the photosensitive drum 53) used for paper conveyance and image formation to form a toner image. The conveyance path 4b, the image forming unit 5, the intermediate transfer unit 6a, and the fixing unit 6b are actually controlled.

  The multifunction device 400 includes an I / F unit 74 (corresponding to an input unit) as a communication interface with the outside. The I / F unit 74 includes, for example, a data communication unit 741 for communicating with the external computer 200 via a network or a cable. The data communication unit 741 includes, for example, a connector for connecting to the network or directly connecting the multi-function device 400 and the computer 200, a controller for controlling communication, and a chip. The data communication unit 741 allows the multi-function device 400 to receive print data including image data and print setting data from the computer 200 or the like (printer function).

  Further, the I / F unit 74 can include a FAX communication unit 742 for performing communication with the external FAX apparatus 300. The FAX communication unit 742 is a part for performing a function as a facsimile, and includes a modem, a circuit for converting image data into a format corresponding to the facsimile, and decompressing received data, a chip, and the like.

  The control unit 7 is also communicably connected to the operation panel 1 via a bus, a communication line, or the like. Data indicating the setting contents set on the operation panel 1 is sent to the control unit 7, and the control unit 7 controls the multifunction device 400 to operate according to the user's settings. The multi-function device 400 also includes a compression processing unit 81 that performs compression processing on image data, and a decompression processing unit 82 that performs decompression processing on the compressed image data. Details of the compression processing unit 81 and the decompression processing unit 82 will be described later.

  The multi-function device 400 includes a page memory 9 having a capacity capable of temporarily storing at least one page of image data, and a banding unit 91 that divides one page of image data into a plurality of bands. Reading and writing of the page memory 9 are controlled by the memory control unit 8 described above. Details of the page memory 9 and the banding unit 91 will be described later.

  The image processing unit 90 provided in the multi-function peripheral 400 includes, for example, an ASIC 92 as a circuit dedicated to image processing, a work memory 93 which is a memory for image processing, and the like (see FIG. 4). Then, the image processing unit 90 performs various image processing such as density change, enlargement / reduction (zoom), and filter processing on the image data. Since image processing that can be performed by the image processing unit 90 is diverse, description of details of executable image processing is omitted on the assumption that image processing related to the known multifunction machine 400 can be performed.

  The memory control device 100 according to the present invention is included in the multifunction device 400. For example, the memory control device 100 includes an image reading unit 2, an I / F unit 74, a banding unit 91, a compression processing unit 81, an expansion processing unit 82, and the like as an input unit of image data handled by the memory control device 100. The image processing unit 90, the page memory 9, the memory control unit 8, and the like (an example of the memory control device 100 is shown by a broken line in FIG. 3).

(Input image data)
Next, an example of input of image data to the memory control device 100 or the multifunction peripheral 400 according to the embodiment of the present invention will be described based on FIGS. FIG. 4 is a block diagram showing an example of the flow of input image data in the memory control apparatus 100 according to the embodiment of the present invention. FIG. 5 is an explanatory diagram showing an example of image data division by the banding unit 91 according to the embodiment of the present invention.

  In the multifunction device 400 of this embodiment, for example, the image reading unit 2 and the I / F unit 74 function as an input unit that inputs image data to the multifunction device 400. The image reading unit 2 as an input unit reads, for example, an original document line by line from the head line in the sub-scanning direction, which is an optical reading line, under the control of the control unit 7. This is a known scanner unit that generates image data. The read image data for each line is output to the banding unit 91. Note that the image data from the image reading unit 2 may be input to the banding unit 91 via the control unit 7.

  The I / F unit 74 as an input unit is an interface for receiving print data including image data from the computer 200 or the counterpart FAX apparatus 300, for example, under the control of the control unit 7. Image data input from the outside is output to the banding unit 91. Note that the image data from the I / F unit 74 may be input to the banding unit 91 via the control unit 7. Note that in the MFP 400 according to the present embodiment, image data stored in the HDD 73 can be used for printing or the like by an operation on the operation panel 1. Therefore, the HDD 73 also serves as an image data input unit for the banding unit 91.

  The banding unit 91 sequentially controls the image data input to the banding unit 91 under the control of the control unit 7 so that a plurality of lines (for example, every 250 lines) from the first line in the sub-scanning direction are set as one band. Banded and output for each band. The processing of the banding unit 91 will be described with reference to FIG.

  For example, the image reading unit 2 of the present embodiment reads an image of a document with a resolution of 600 dpi and outputs image data. For example, in the case of image data corresponding to the A4 size, when the long side of the A4 sheet coincides with the sub-scanning direction, if 1 inch = 2.54 cm, about 29 cm / (2 in the long side direction of A4 .54 ÷ 600) ≈6860, and about 7000 lines are included in the image data in the sub-scanning direction.

  In the description of the present embodiment and the following description, an example in which one piece of image data is divided into 14 bands will be described. Therefore, in the case of image data corresponding to A4, 7000 ÷ 14≈500 lines, and the banding unit 91 divides the image data corresponding to A4 into bands every about 500 lines. FIG. 5 schematically shows the division of the band.

  The memory control device 100 is provided with an image processing unit 90 that performs processing of banded image data. The image processing unit 90 includes an ASIC 92 and a work memory 93 as a work area for image processing. Although a plurality of work memories 93 may be provided, FIG. 4 shows one work memory for convenience. The image processing unit 90 uses, for example, an ASIC 92 to perform image detection processing such as density and color / monochrome discrimination processing for image data.

  The image processing unit 90 is provided with, for example, a zoom processing unit 94, a density conversion processing unit 95, and a filter processing unit 96. In other words, the image processing unit 90 performs at least zoom processing, density conversion processing, and filter processing. The zoom processing unit 94, the density conversion processing unit 95, and the filter processing unit 96 may be functionally realized by the ASIC 92. The zoom processing unit 94 enlarges and reduces the image data. With the printer driver software installed on the operation panel 1 or the computer 200, density setting (shading setting) in printing or the like is possible. The density conversion processing unit 95 converts each pixel value of the image data in a direction of increasing or decreasing according to the density set by the user.

  The filter processing unit 96 applies various filters to the banded image data, and performs a process of converting each pixel in the image data. In the MFP 400 according to the present embodiment, a character mode (a mode that prioritizes the image quality of characters in a document) and a photo mode (a mode that prioritizes the image quality of photos in a document) can be selected on the operation panel 1 during copying. . For example, when the character mode is selected, the filter processing unit 96 applies a differential filter to the banded image data, emphasizes edges, and sharpens the characters. For example, when the photo mode is selected, the filter processing unit 96 applies an integration filter to the banded image data, smoothes the pixel value of each pixel in the band, and smoothes the color change. .

  The image processing unit 90 can perform other image processing on the banded image data (for example, rotation processing, black-and-white reversal processing, binarization processing, frame removal processing, etc.). However, the description of all image processing that can be performed is out of the spirit of the present invention, and therefore detailed description is omitted assuming that known image processing can be performed.

  The compression processing unit 81 performs compression processing for compressing the banded image data using a predetermined file format or compression method. For example, the compression processing unit 81 compresses the image data into JPEG (Joint Photographic Experts Group). Then, the compression processing unit 81 outputs the page memory 9. Further, the compression processing unit 81 performs processing for compressing the image data output from the page memory 9 and subjected to image processing such as filter processing into, for example, JPEG, and outputs it to the page memory 9 again.

  The decompression processing unit 82 performs decompression processing of the band output from the page memory 9 for image processing. Then, the expansion processing unit 82 outputs the band after the expansion processing to the image processing unit 90. As shown in FIG. 4 and the like, in this description, the compression processing unit 81 and the decompression processing unit 82 are described as being separate from the image processing unit 90, but may be included in the image processing unit 90. .

  The page memory 9 has a necessary storage block M having a capacity of one page of image data (the number of bands of one page) and an additional storage block m having a capacity of one band (see FIGS. 7 and 8). . For example, the page memory 9 is a semiconductor memory, and can read and write image data for one page for each band under the control of the control unit 7 (memory control unit 8). Note that the memory control unit 8 is connected to, for example, the image processing unit 90 and controls reading and writing in the page memory 9 while confirming the progress of image processing in the image processing unit 90.

  The page memory 9 receives and stores image data for each band, outputs image data for each band for image processing, and re-images image data of the same page processed by the image processing unit 90 for each band. Receive and record. Thus, the page memory 9 stores, outputs, and re-stores image data of the same page.

(Image processing using page memory 9)
Next, an outline of image processing using the page memory 9 according to the embodiment of the present invention will be described with reference to FIG. FIG. 6 is a block diagram showing an outline of image processing of the flow of image data using the page memory 9 according to the embodiment of the present invention.

  As shown in FIGS. 5 and 6, the image data generated by the image reading unit 2 and the image data received by the I / F unit 74 are transmitted to the banding unit 91. The banding unit 91 sequentially outputs image data in band units. The band output from the banding unit 91 is input to the compression processing unit 81. The compression processing unit 81 performs compression processing such as JPEG for each band and outputs the result to the page memory 9.

  The page memory 9 stores the band from the compression processing unit 81. Then, after storing all the bands for one page or in parallel with the storage of the bands, the page memory 9 outputs the stored bands to the decompression processing unit 82 for image processing. The decompression processing unit 82 receives the band from the page memory 9 and performs decompression processing. Then, the decompression processing unit 82 outputs to the image processing unit 90.

  The image processing unit 90 performs image processing using the work memory 93 based on the band after the expansion processing. For example, as shown in FIG. 6, the image processing unit 90 is provided with a plurality of work memories 93, and the image processing unit 90 can perform a plurality of types of image processing before the page memory 9 stores the bands again. . When the band passes through the image processing unit 90, it is not always necessary to perform a plurality of times of image processing, and it may be performed once.

  Then, the image processing unit 90 outputs the band after image processing to the compression processing unit 81. The compression processing unit 81 performs compression processing on the band after image processing. Then, the compression processing unit 81 outputs the compressed band after image processing to the page memory 9. The page memory 9 stores the compressed band after image processing in band units.

  Then, according to the settings on the operation panel 1 of the user, the band output from the page memory 9, decompression processing, image processing, compression processing, and the page of the band subjected to compression processing until all necessary image processing is performed. The re-storing of the memory 9 is repeated.

  For example, the image processing unit 90 performs a first process on the banded image data, for example, an image detection process such as a density or color / monochrome discrimination process on the image data, and then temporarily stores the page memory 9. Remember me. Next, image processing is performed for each band of the same page, for example, second processing such as image data scaling processing (for example, equivalent to image processing 1 in FIG. 6) or filtering processing (for example, image processing in FIG. 6). 2) and density conversion processing (e.g., equivalent to image processing 3 in FIG. 6), and are temporarily stored in the page memory 9. As described above, the image processing unit 90 can perform a combination of a plurality of types of image processing in the loading and unloading of the band from the page memory 9 once. The multiple types of image processing are not limited to scaling processing, filter processing, and density conversion processing, and other types of image processing may be combined.

  Further, next, the image processing unit 90 performs third processing, for example, image processing such as binarization of the image data subjected to the second processing, on each band of the same page, and stores them in the page memory 9. Let As described above, the image processing unit 90 can perform a plurality of stages of image processing such as the first processing, the second processing, and the third processing on the banded image data, and a plurality of image data on the same page. Reading from the page memory 9 and writing are performed.

  When necessary image processing is completed, image data is output from the page memory 9 and transmitted to each unit. When printing, the image data output from the page memory 9 is transmitted to the exposure device 52 and used to form a toner image. The image data output from the page memory 9 is transmitted to the HDD 73 when the document is scanned and stored in the multi-function device 400. The image data output from the page memory 9 is transmitted to the I / F unit 74 when the scanned image data is transmitted to the computer 200 or the FAX apparatus 300. Note that image data may be transmitted from the page memory 9 to each unit via, for example, the control unit 7, the HDD 73, the RAM 72, or the like, or may be directly transmitted from the page memory 9 to each unit.

(Reuse of page memory 9)
Next, an example of usage in the page memory 9 according to the embodiment of the present invention will be described with reference to FIGS. FIG. 7 is an explanatory diagram regarding the use and operation of the storage area of the page memory 9 according to the embodiment of the present invention. FIG. 7A shows the storage area when all bands of image data for one page are stored. (B) shows an example of the first band process, (c) shows an example of the second band process, and (d) shows an example of the third band process.

  FIG. 8 is also an explanatory diagram regarding the use and operation of the storage area of the page memory 9 according to the embodiment of the present invention. FIG. 8A shows an example of the processing of the fourth band, and all of the image data for one page is shown. The storage area when the band is stored is shown, (b) shows an example of overwriting of the sixth band by the fifth band, and (c) shows an example of a process of waiting for writing until the free space becomes sufficient. (D) shows an example of processing of the fifth band.

  In FIG. 7 and FIG. 8, odd-numbered bands are indicated by shading. Further, the band to be written is shown by filling.

  First, the page memory 9 is provided with two blocks, a necessary storage block M and an additional storage block m, as shown in FIGS. The boundary between the two blocks is indicated by a broken line. For example, the capacity of the necessary storage block M is ensured to store at least one page of image data when one page of image data is compressed.

  For example, in the memory control device 100 of this embodiment, the maximum size for one page of input image data is determined (for example, image data read by the image reading unit 2 and 600 dpi in A4 size). In the case of JPEG compression performed by the compression processing unit 81, the size of image data for one page after compression is roughly determined by the Quality value with respect to the maximum size of input image data.

  Then, for example, for the compressed image data, the case where the compression ratio of the image data becomes the worst is obtained in advance by an experiment or the like by reading various originals, and one page when the compression ratio of the image data is the worst. The capacity of the necessary storage block M of the page memory 9 can be determined based on the size of the image data. In other words, the capacity of the necessary storage block M can be determined on the assumption that the size of the image data for one page is the largest. Thus, the necessary storage block M can store at least one page of compressed image data. Note that the number of page memories 9 is not limited to one, and a plurality of page memories 9 may be provided according to the corresponding paper size (for example, A3 and A4). The page memory 9 may be provided for a plurality of pages.

  The additional storage block m is a storage area provided for effectively using the page memory 9 and is an area added to the necessary storage block M. In the case of JPEG compression performed by the compression processing unit 81, the size of one band after compression is roughly determined by the Quality value. For example, when one page of image data is banded, the case where the compression ratio is the worst is obtained in advance by experiments by reading various originals. The capacity of the additional storage block m of the page memory 9 can be determined based on the band size when the compression rate becomes the worst. In other words, the capacity of the additional storage block m can be determined on the assumption that the size of the band data is the largest. As a result, the additional storage block m can store at least one band of compressed image data.

  When a document is read by the image reading unit 2 or image data is input to the I / F unit 74 from the computer 200 or the like, the page memory 9 stores and stores image data for one page. Before storage and storage, the page memory 9 is empty and in a released state.

  Then, as shown in FIG. 7A, the page memory 9 first stores all bands of image data for one page in the necessary storage block M. First, when storing image data for one page, as shown in FIG. 7A, the memory control unit 8 is the head point P in the address of the page memory 9 in order from the band (1), and is necessary. From the storage block M, image data is stored in band order in a fixed direction of address.

  In the description of the present embodiment, since one page of image data is divided into 14 bands, the numbers (1) to (14) are assigned to the bands in each of FIGS. . And it shows that the size of the data after compression of a band is so large that the area which a band occupies is large.

  When the storage of the image data for one page in the page memory 9 is completed, the image data is read from the page memory 9 in order from the band (1) for image processing. Reading and writing in the page memory 9 is FIFO (First In, First Out). After the image processing in the image processing unit 90, the page memory 9 can store the band again.

  In FIG. 7 and FIG. 8, a band output from the page memory 9 and written again in the page memory 9 after image processing is indicated by “′”, and is first written in the page memory 9. These are shown separately from each band.

  At this time, as shown in FIG. 7B, the band (1) 'is stored following the band (14). In other words, in principle, the page memory 9 stores the bands in the order of addresses following the band stored immediately before.

  Eventually, the capacity of the necessary storage block M is used up, and band writing in the additional storage block m begins. As shown in FIG. 7C, the size of the band (2) 'obtained by performing the image processing on the band (2) is within the free space of the additional storage block m. Therefore, as shown in FIG. 7C, after the image processing, the band (2) ′ is stored in the additional storage block m.

  Next, as shown in FIG. 7D, the band (3) is read from the page memory 9, and image processing is performed. In the additional storage block m, the memory control unit 8 attempts to write the band (3) ′ obtained by performing image processing on the band (3) and compressing it. However, as shown in FIG. 7D, the data size of the band (3) ′ obtained by performing image processing on the band (3) is larger than the free capacity of the additional storage block m. Therefore, it is not possible to write all the band (3) 'in the empty space of the additional storage block m. Therefore, the memory control unit 8 returns to the starting point P of the necessary storage block M and writes the band (3) ′ to the page memory 9.

  Next, as shown in FIG. 8A, the band (4) is read from the page memory 9, and image processing is performed. Then, the memory control unit 8 confirms an empty area of the page memory 9. Note that the memory control unit 8 treats the original band (4) as a free space in order to reuse the page memory 9. As shown in FIG. 8A, the free space in the page memory 9 is sufficient up to the address where the band (5) is stored. Therefore, the memory control unit 8 causes the page memory 9 to write the band (4) ′ obtained by performing the image processing and compressing the band (4) after the band (3) ′.

  Here, the memory control unit 8 checks whether or not the free space of the page memory 9 is sufficient. For example, the memory control unit 8 needs to have enough free space for the size of the band data after image processing. Data such as a table indicating whether the band data after image processing is compressed is stored. An arithmetic expression may be used instead of the table. Then, when writing to the page memory 9, the memory control unit 8 confirms the free capacity of the page memory 9 and communicates with the image processing unit 90 to confirm the size of the band data after the image processing. Then, the memory control unit 8 performs an operation based on a table or an arithmetic expression, and confirms whether or not the free space of the page memory 9 is sufficient.

  Similarly to the case of the additional storage block m, the memory control unit 8 tries to write a band after image processing and compression, and overwrites a band that has not been output from the page memory 9 (band waiting for image processing). Whether or not the free space of the page memory 9 is sufficient may be confirmed.

  Next, the band (5) is read from the page memory 9 and image processing is performed. Then, the memory control unit 8 confirms an empty area of the page memory 9. Note that the memory control unit 8 treats the original band (5) as a free space in order to reuse the page memory 9. However, as shown in FIG. 8B, if the band (5) 'is written as it is after the band (4)', a part of the band (6) is overwritten. This overwriting becomes a cause of abnormal image generation.

  The cause of the occurrence of such overwriting is, for example, the band (for example, the band (3) ′) stored in the page memory 9 again, as can be seen by comparing FIG. 7 (a) and FIG. 8 (b). This is because the band (5) ′) is larger than the original size. When image processing is performed, the compression rate may deteriorate. For example, for image data obtained by reading a catalog or pamphlet with photos, a differential filter is applied to each band by selecting the character mode, and the pixel value of each pixel in the image data is converted, then the band is compressed. The rate may be worse.

  Therefore, in the memory control device 100 of the present embodiment, when the memory control unit 8 determines that the free space of the page memory 9 is not sufficient, as shown in FIG. Writing is paused and the next and subsequent bands are output first. The next and subsequent bands wait for rewriting to their own page memory 9 in the work memory 93 of the image processing unit 90.

  Then, as shown in FIG. 8D, the memory control unit 8 outputs the band (6), and handles the area up to the band (6) as a free space, so that the band (5) ′ is written. It is determined that there is enough free space. Then, as shown in FIG. 8D, the memory control unit 8 causes the band (5) ′ to be written in the empty area. After the band (6), the page memory 9 is reused until necessary image processing is completed.

(Image data processing flow)
Next, an example of the flow of image data processing in the memory control device 100 according to the embodiment of the present invention will be described with reference to FIG. FIG. 9 is a flowchart showing an example of image data processing in the memory control apparatus 100 according to the embodiment of the present invention.

  First, the start in FIG. 9 is a point in time when image data is input to the memory control device 100 by reading an original in the image reading unit 2 and the page memory 9 starts storing image data for one page. It is. At this time, for example, the page memory 9 is empty and in a released state.

  Then, the program according to the invention is activated, and the image data is input to the banding unit 91. The banding unit 91 performs banding of the image data by setting a certain number of lines from the first line in the sub-scanning direction as one band. The image data is output for each band (step # 1).

  Then, the image processing unit 90 performs image detection processing such as density and color / monochrome discrimination processing on the banded image data (step # 2, first processing). The compression processing unit 81 performs compression processing of the band output from the image processing unit 90 (step # 3). Each compressed band is sequentially stored from the beginning point P of the address of the page memory 9 (step # 4).

  Next, the memory control unit 8 outputs the first band (band (1)) from the page memory 9 (step # 5). Then, the decompression processing unit 82 performs decompression processing of the band output from the page memory 9 (step # 6). Next, the image processing unit 90 performs image processing such as density conversion processing and filter processing on the expanded band (step # 7, second processing). Then, the compression processing unit 81 performs compression processing on the band after image processing (step # 8).

  Then, the memory control unit 8 confirms whether the write start position of the band is the additional storage block m (step # 9). In other words, it is confirmed whether writing is started in the additional storage block m (step # 9). If it is a write in the additional storage block m (Yes in step # 9), the memory control unit 8 tries to write in the additional storage block m (step # 10).

  Then, the memory control unit 8 confirms whether or not the entire band has been written in the additional storage block m (step # 11). If writing is not possible (No in step # 11), the memory control unit 8 returns to the top position of the page memory 9 and causes the page memory 9 to write a band (step # 12). In other words, the page memory 9 is reused and writing from the head position is started again.

  That is, the memory control device 100 according to the present embodiment divides the image data into an input unit (image reading unit 2 or the like) and a plurality of bands in order from the head of the input image data for one page. The banding unit 91, the compression processing unit 81 that performs compression processing of image data, the decompression processing unit 82 that decompresses compressed image data, and the image processing of the image data decompressed by the decompression processing unit 82 The image processing unit 90 is divided into a plurality of blocks, outputs image data in band units to the decompression processing unit 82, and the image data input to the input unit (image reading unit 2 or the like) or the image processing unit 90 The processed image data, the image data compressed by the compression processing unit 81 is received and stored in band units, and written in band order in band units in a fixed direction from the start point P of the address. When the last block (additional storage block m) in the writing direction of the page memory 9 is reached, the page memory 9 for reusing the memory is returned to the starting point P, and the output and writing from the page memory 9 are controlled. It is determined whether the free space of the block is smaller than the compressed data size of the band to be written. If the free space of the final block is smaller than the compressed data size of the band to be written, A memory control unit 8 is provided for returning and writing. Specifically, the memory control unit 8 attempts to write the compressed band in the final block (additional storage block m) in the writing direction of the page memory 9 and determines whether or not all the band data can be written. It is determined whether the free capacity of the block (additional storage block m) is smaller than the data size of the band to be written.

  On the other hand, when the data can be written (Yes in Step # 11) or after Step # 12, the memory control unit 8 completes the image processing to be performed for all the bands and finishes storing in the page memory 9. (Step # 13). For example, in the case of the output from the page memory 9 and the rewriting to the page memory 9 for the first band (1), step # 13 is No, the band is read a plurality of times, and the loop returns to step # 13. When returning, step # 13 is Yes.

  If image processing to be performed is completed for all bands and storage in the page memory 9 is completed (Yes in step # 13), the memory control unit 8 outputs the control unit 7, the HDD 73, the exposure device 52, and the like. First, image data is output to the page memory 9 (step # 14). For example, when the page memory 9 outputs image data to the exposure device 52, the image data is delivered to the exposure device 52 after the expansion processing by the expansion processing unit 82. When the page memory 9 outputs image data to the HDD 73, the image data may be transferred to the HDD 73 in a compressed state. Then, the processing of the image data for one page is completed (end). On the other hand, if the image processing to be performed is not completed for all bands (No in step # 13), the memory control unit 8 outputs the next band (step # 15) and returns to step # 6.

  On the other hand, if the write start position is not the additional storage block m but the necessary storage block M (No in step # 9), the memory control unit 8 communicates with the image processing unit 90 to free the page memory 9 It is confirmed whether the capacity is sufficient (step # 16). As described above, for example, the memory control unit 8 communicates with the image processing unit 90, predicts the size of the compressed data of the band to be written to the page memory 9 using a table or the like, and frees the page memory 9. If the free space of the page memory 9 is larger than the free space of the page memory 9, it is determined that the free space of the page memory 9 is sufficient.

  If the memory control unit 8 determines that the free space of the page memory 9 is not sufficient (No in step # 16), the memory control unit 8 confirms whether there is a band to be subjected to image processing (step #). 17). In other words, it is confirmed whether there is a band waiting for image processing to be output next (step # 17). Next, if there is a band to be output (Yes in step # 17), the memory control unit 8 confirms whether the work memory 93 of the image processing unit 90 is not full and the band can be output. (Step # 18).

  If the work memory 93 of the image processing unit 90 is not full and a band can be output (Yes in step # 18), the next band is output (step # 19). That is, the image processing unit 90 has a work memory 93 as a work area for performing image processing, and the page memory 9 sends image data to the decompression processing unit 82 for image processing in the image processing unit 90. When the page memory 9 stores the band after compression, the image processing unit 90 performs image processing, and the compression-processed band is stored again. The memory control unit 8 determines whether or not the free capacity of the page memory 9 is smaller than the compressed data size of the band to be written, and if so, the compressed data of the band to be written is determined. Until the free space of the page memory 9 corresponding to the size is secured, the image data is sent to the decompression processing unit 82 in the band unit in the page memory 9 while waiting for the writing of the band. Is output, after the free space is secured, to write the band that was allowed to stand in the page memory 9.

  Also for the next band, decompression processing (step # 20) and image processing are performed (step # 21). Thereafter, the process returns to step # 16. If there is no band to be subjected to image processing next (No in step # 17), and if the work memory 93 is already full and no band can be output (No in step # 18), the page memory 9 is loaded. When writing is performed, overwriting occurs and an abnormal image is generated. Therefore, the memory control unit 8 informs the control unit 7 of the occurrence of an overwrite error, and the control unit 7 notifies the operation panel 1 of the occurrence of the error (step # 22). And this control is complete | finished (end).

  That is, the memory control unit 8 waits for writing of the band, and even if the page memory 9 outputs image data to the decompression processing unit 82 in units of bands until the work memory 93 is completely filled, the band to be written is written. When the free space of the page memory 9 corresponding to the data size after compression cannot be secured, the error occurrence is recognized, and when the memory control unit 8 recognizes the error occurrence, a notification unit (operation panel 1) for notifying the occurrence of the error Have

  On the other hand, when the memory control unit 8 determines that the free space in the page memory 9 is sufficient (Yes in step # 16), the compression processing unit 81 performs compression processing on the band after image processing (step # 23). ). Then, the memory control unit 8 causes the compressed band to be written in the empty area following the already written band (step # 24).

  Then, the memory control unit 8 confirms whether there is a band output in step # 19, stored in the work memory 93 and subjected to image processing, but not yet written in the page memory 9 (step # 25). If there is a band not yet written in the page memory 9 (Yes in step # 25), the process returns to step # 16. On the other hand, if there is no band not written in the page memory 9, the process proceeds to step # 13.

  Thus, according to the present invention, when the last block (additional storage block m) in the writing direction of the page memory 9 is reached, the free space of the last block is smaller than the data size after compression of the band to be written. Returning to the top point P, writing is performed. As a result, when writing to the page memory 9 from the beginning point P of the address (using the page memory 9), the capacity of the page memory 9 is used to the limit, and the page memory 9 is effectively utilized. can do.

  Also, in the last block (additional storage block m) in the writing direction of the page memory 9, an attempt is made to write the band after compression, and the free capacity of the last block is written depending on whether or not all the band data can be written. It is determined whether or not the data size is smaller. Since it is actually tried in this way, it is clearly confirmed whether or not a band after image processing compressed in the final block can be written. Therefore, the page memory 9 can be reliably used up to the capacity limit, and the page memory 9 can be used effectively.

  If the free space of the page memory 9 is smaller than the data size after compression of the band to be written, the band until the free space of the page memory 9 for the data size after compression of the band to be written is secured. The image data is output to the page memory 9 in the band unit toward the decompression processing unit 82 while waiting for the writing, and after being secured, the band that has been waiting is written to the page memory 9. As a result, the free band of the page memory 9 is secured, and the compressed band after image processing is written. Therefore, it is possible to prevent the band after image processing from being overwritten on the band that has not yet been output from the page memory 9 for image processing.

  Further, even if image data is output to the decompression processing unit 82 in band units in the page memory 9 until the work memory 93 is filled up while waiting for writing of the band, the data size corresponding to the data size after compression of the band to be written If the free capacity of the page memory 9 cannot be secured, the occurrence of an error is recognized. Accordingly, it is possible to notify the user that abnormal image data is generated. In addition, the user can be informed that even if the work memory 93 is used to the limit, the band that has not been output from the page memory 9 may be overwritten after the compressed image processing. This makes it possible for the user to recognize the necessity of countermeasures such as changes in the settings.

  The image processing unit 90 performs at least zoom processing, density conversion processing, and filter processing. For example, in image processing involving conversion of the pixel value of each pixel in these image data, the band compression rate may deteriorate. However, even if the image processing unit 90 that performs these image processes is included, it is possible to prevent overwriting of a band after compressed image processing to a band that has not yet been output from the page memory 9 for image processing. it can.

  In addition, the memory control device 100 prevents overwriting of a band after compressed image processing to a band that has not yet been output from the page memory 9 for image processing. It is possible to provide an image forming apparatus that does not perform printing based on simple image data.

  The embodiment of the present invention has been described above, but the scope of the present invention is not limited to this, and various modifications can be made without departing from the spirit of the invention.

  The present invention is mounted on an image forming apparatus such as a multifunction machine, a copier, a facsimile machine, and a printer, and can be used for a memory control device including a page memory and a memory control unit.

1 Operation panel (notification unit) 2 Image reading unit (input unit)
74 I / F unit (input unit) 81 Compression processing unit 82 Decompression processing unit 9 Page memory 90 Image processing unit 91 Banding unit 93 Work memory 100 Memory control device 400 Multifunction device (image forming device)
M Necessary storage block (part of page memory)
m Additional storage block (last block, part of page memory)

Claims (6)

An input unit for inputting image data;
A banding unit that divides input image data for one page into a plurality of bands;
A compression processing unit for compressing image data;
A decompression processing unit for decompressing the compressed image data;
An image processing unit for performing image processing of the image data expanded by the expansion processing unit;
Image data divided into a plurality of blocks, output image data in units of bands toward the decompression processing unit, and image data input to the input unit or image data processed by the image processing unit, wherein the compression The image data compressed by the processing unit is received and stored in units of bands, and is written in the bands in units of the bands in a certain direction from the start point of the address, and when the final block in the writing direction is reached, Page memory to go back to the starting point and recycle memory,
Controls output and writing from the page memory, determines whether or not the free capacity of the final block is smaller than the compressed data size of the band to be written, and the free capacity of the final block is also written A memory control device comprising: a memory control unit that returns to a head point and performs writing when the data size after compression of the band to be compressed is smaller.   The memory control unit attempts to write the band after compression in the last block of the page memory, and depending on whether or not all the data of the band can be written, the free capacity of the last block is determined for the band to be written. 2. The memory control device according to claim 1, wherein it is determined whether or not the data size is smaller. The image processing unit has a work memory as a work area for performing image processing,
For image processing in the image processing unit, the page memory outputs image data to the decompression processing unit, image processing is performed in the image processing unit, and the band after compression processing is stored in the page memory. If you want to remember again,
The page memory treats the storage area of the band portion output to the decompression processing unit as a free space,
The memory control unit determines whether or not the free space of the page memory is smaller than the compressed data size of the band to be written, and if so, the page memory while waiting for the band to be written The image data is output to the decompression processing unit for each band, and after the free space is secured, the band that has been waiting is written to the page memory. The memory control device described. The memory control unit waits for writing of the band, and even if the page memory outputs image data to the decompression processing unit in units of bands until the work memory is completely filled, the memory control unit tries to write If free space of the page memory for the data size after compression of the band cannot be secured, recognize the error occurrence,
The memory control device according to claim 1, further comprising a notification unit that notifies of occurrence of an error.   5. The memory control device according to claim 1, wherein the image processing unit performs at least zoom processing, density conversion processing, and filter processing.   An image forming apparatus comprising the memory control device according to claim 1.

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