JP4136335B2 - Image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile, or the like provided with means (for example, an HDD) for compressing input digital image data and storing the compressed image data. It has a function to manage the conversion matrix (table) used for compression processing of the binary image after processing, and when restoring the compressed stored data, processing may be disabled even if the generation of the table used at the time of compression is different The present invention relates to the image forming apparatus.
[0002]
[Prior art]
In an apparatus conventionally known as a digital multifunction peripheral (an image forming apparatus having a combination of functions such as copying, facsimile, and printer), image data read by a document image reading unit or image data input from the outside Is provided with a storage device having a large-capacity storage medium for digitizing and storing. A magnetic disk device (hereinafter referred to as “HDD (Hard Disk Drive)”) is generally used for this type of storage device.
The input image data is accumulated in the HDD as necessary, and is used when temporarily saved data such as sort printing or when a print request is made again by a user operation after accumulation. The function of accumulating image data in the HDD is hereinafter referred to as local storage.
In addition, when storing in the HDD, the dithered binary image data is stored by reducing the amount of data by compression processing, and causes the compressor to perform processing using an algorithm such as run-length compression.
[0003]
By the way, when compressing a dithered binary image using an algorithm by run-length compression, an adaptive rearrange method (hereinafter referred to as ARM: Adaptive) is used to improve the compression rate and realize high-speed processing. A binary image conversion method (abbreviated as Re-arranging Method) has been proposed and applied (Japanese Patent Application No. 2000-18214).
ARM is a high-efficiency binary image conversion method mainly for printers, and is incorporated in the previous stage of the compressor, and performs processing to adaptively rearrange the dithered binary pixels in a fixed pixel unit (hereinafter referred to as ARM). The compression process using is described as “rear range process”), and the subsequent run length compression process is made more efficient by the rear range. A conversion matrix (referred to as a rearrange matrix) is used for the rearrange processing. The rearrange matrix is created based on the dither matrix used for the previous dither processing (conversion to a binary image) and takes the form of a rearrange table.
At the time of printing, the rearranged image stored in the HDD is taken out and the original binary image is restored. At this time, it is necessary to decompress using the rearrange table used in the compression. Conventionally, only the latest rearrange table currently used at the time of storage (compression) is stored in the ROM as a rearrange table. Therefore, the latest table used at the time of storage (compression) is also used at the time of restoration (expansion) of the stored image.
[0004]
[Problems to be solved by the invention]
However, since the rearrange table created from the dither matrix evolves with the dither matrix and changes the generation, the rearrange table data may be updated (generation changes) while images are stored in the local storage. When the generation changes, the image that has been rearranged by the table of the previous generation exists in the image stored in the local storage. Therefore, when using the image rearranged by the previous generation table for printing, the latest rearrange table currently stored in the ROM is different from the generation rearrange table used for compression. This causes a problem that the image cannot be restored (expanded).
The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to compress a binary image after dither processing through a rearrange process using a conversion matrix and compress the compressed image data. In an image forming apparatus (for example, a copying machine, a printer, a facsimile, etc.) provided with a means for storing data, it has a function of managing a conversion matrix (table) used for rearrange processing, and restores (decompresses) compressed stored data It is an object of the present invention to provide an image forming apparatus capable of preparing a suitable conversion matrix (table) even when the generation of the table used at the time is different, and preventing the expansion process from being disabled.
[0005]
[Means for Solving the Problems]
According to the first aspect of the present invention, there is provided compression means for compressing a dithered binary image through a rearrange process using a conversion matrix, data storage means for storing the compressed image, and the data storage means. An image forming apparatus provided with decompression means for decompressing an extracted image into an original binary image using a conversion matrix, wherein various conversion matrices set for use in rearrange processing of the binary image are used as the data. stored in the storage means, Ru set Teisu for use in the expanding unit conversion matrix is removed from the data storage means having the same generation identification information and the conversion matrix type used during compression when decompression of the stored image transformation An image forming apparatus including a matrix management unit.
[0006]
According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the conversion matrix management means associates the type information of the conversion matrix used for the rearrange processing of the binary image at the time of image accumulation with each accumulated image. the accumulated in data accumulation means Te, an image forming apparatus is characterized in that the set Teisu so that the decompression means a transformation matrix type accumulated in association with the image at the time of expansion of the accumulation image.
[0007]
According to a third aspect of the present invention, in the image forming apparatus according to the second aspect, the conversion matrix management unit is configured to convert the conversion matrix set in the expansion unit and the conversion matrix associated with the stored image when the stored image is expanded. And the setting is changed to the conversion matrix type stored in association with the stored image when there is a mismatch.
[0008]
According to a fourth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects, the data storage unit is a storage unit including a storage medium that is detachable from the image forming apparatus. The image forming apparatus .
[0009]
DETAILED DESCRIPTION OF THE INVENTION
The image forming apparatus of the present invention will be described based on the following embodiments shown with reference to the accompanying drawings.
FIG. 1 is a schematic configuration diagram showing a digital copying machine as an embodiment relating to an image forming apparatus of the present invention.
First, referring to FIG. 1, an original is read by a reading unit 200 according to setting conditions instructed by a user, and obtained image data is processed by an image processing unit (IPU: image processing unit) 401 to generate a generated image. In accordance with a series of copy processing steps as a copying machine in which a reproduction (copying) image is printed on recording paper by the image forming unit 300 using image data, an apparatus configuration and an outline of the operation of the digital copying machine 100 of this example are described. explain.
On the upper surface of the digital copying machine 100, an operation unit for giving various settings / instructions such as an operation mode desired by the user to the copying machine, and setting conditions and operation states of the copying machine to the user are displayed. An operation / display unit 406 including a display unit for notification from the apparatus side is provided. When the start button on the operation / display unit 406 is pressed by the user, the digital copying machine 100 starts copy processing.
The reading unit 200 scans and exposes a document D placed on a document table (contact glass) 201 with an exposure lamp 202 that moves along the lower surface of the document table 201, and reflects reflected light from the document surface as a CCD image. By performing photoelectric conversion by the sensor 203, an image signal corresponding to the intensity of light is generated. The output signal of the CCD image sensor 203 is input to the signal processing unit 204, amplified to a predetermined voltage amplitude by an amplifier, and then converted to digital data by an A / D conversion circuit. In the process of signal processing by the signal processing unit 204, correction such as shading correction is performed on the signal. The image data processed by the signal processing unit 204 is input to an image processing unit (IPU: image processing unit) 401 together with an image synchronization signal.
[0010]
The scanner control unit 205 monitors the detection signals from various sensors and controls the scan drive motor according to the detection signals in order to execute the above-described process of the reading unit 200, and also performs shading of the signal processing unit 204. Various parameter setting processing is performed on the processing unit and the IPU 401.
In the IPU 401, the input image data from the signal processing unit 204 is subjected to two-dimensional real-time scaling processing, MTF correction that increases resolution of characters, line images, etc., smoothing that improves signal reproducibility and removes image noise. Spatial filter processing for performing processing, etc., gamma correction processing according to the density setting function, and gradation processing for performing halftone processing according to the image quality setting function are performed.
As part of the processing, the IPU 401 cooperates with the system control unit 405 to input image data to a readable / writable storage unit (for example, HDD) 402 having a large capacity removable storage medium. The data is stored (local storage), and the locally stored data is used as temporarily saved data such as sort printing, or is used when a print request is made again by a user operation after storage. Here, since the image data stored in the storage unit 402 is compressed (decompressed when restored), a memory control unit 409 having a processing function for that purpose and an access control function for the storage unit 402 is provided.
[0011]
In the image forming unit 300, the image data from the IPU 401 is sent to the writing unit 301. The writing unit 301 has a built-in laser light source, and modulates the laser light source with the image data from the IPU 401 while rotating at a constant speed uniformly charged by the charging charge 302 by the laser beam emitted from the light source. The surface of 303 is scanned. As a result, an electrostatic latent image corresponding to the original image is formed on the photosensitive member 303. A visible image is obtained by developing the electrostatic latent image on the photosensitive member 303 with toner by the developing device 304. Then, the transfer paper (not shown) that has been previously fed from the paper feed trays 306 </ b> A to 306 </ b> D by the paper feed roller 305, contacts the registration roller 307, and waits is registered with the rotation of the photoconductor 303. Is transferred to the transfer position, and the toner on the photosensitive member 303 is electrostatically transferred onto the transfer paper by the transfer charger 308. Thereafter, the transfer paper is separated from the photosensitive member 303 by the separation charger 309, the toner image on the transfer paper is heated and fixed by the fixing device 310, and discharged onto the discharge tray 312 by the discharge roller 311. On the other hand, after electrostatic transfer, the toner remaining on the photoconductor 303 is removed by the cleaning device 313, and the photoconductor 303 is discharged by the charge removal charger 314. The plotter control unit 315 monitors the detection signals from various sensors and controls the drive motor and the like according to the detection signals in order to execute the process of the image forming unit 300 described above.
The system control unit 405 constitutes an operating system for controlling the entire copying machine including the scanner control unit 205 and the plotter control unit 315. The system control unit 405 stores a program and data for configuring the operating system in a built-in ROM, and has a large capacity that can be detached from the outside so as to store data used by the operating system as needed. A readable / writable storage unit (for example, HDD) 402 having a storage medium has an area for this purpose.
[0012]
Next, the local storage of the input image data described above, that is, the process of accumulating in the storage unit 402 having a large-capacity storage medium detachable from the outside will be described in detail.
In the case of local storage, the input image data stored in the HDD serving as the storage unit 402 having a large-capacity storage medium that can be attached and detached from the outside is compressed as described above. In this compression, when the input image is a dithered binary image, run length compression is performed through a rearrange process using a conversion matrix (see Japanese Patent Application No. 2000-18214). When the stored image is used, it is decompressed in order to restore the original binary image. At this time, it is necessary to use the same conversion matrix used at the time of compression.
The conversion matrix used for such rearrange processing can be implemented in the form of a rearrange table, and is linked to the matrix used for dither processing. The rearrange table is updated as the dither matrix changes (generation changes). There must be. In the present invention, even if the type (generation) of the rearrange table used when decompressing (decompressing) the compressed accumulated data is different from the latest table currently loaded for use in accumulation (compression), An applicable table can be prepared so as to prevent the expansion process from being disabled, and a conventional problem that cannot be adapted to the difference in table generation is solved.
[0013]
As a solution, in the present invention, by storing the rearrange table used at the time of compression as a file in the HDD, table data of a different generation from the rearrange table currently loaded on the ROM is required at the time of decompression. If it becomes, it can be removed from the HDD.
In addition, management of such a generation (in this embodiment, since the table data type to be managed is a generation, the table data type is hereinafter referred to as a generation), that is, the table used at the time of restoration (decompression) is associated with the stored image and managed. In order to do this, information (for example, a generation number) for identifying the generation of the rearrange table is added to the rearrange table data file and the stored (compressed) image data. By managing the rearrange table and accumulated image data using generation identification information, the consistency of the generation of the table used at the time of decompression is judged, and if not matched, the generation identification information is determined from the rearrange table data stored in the HDD. Thus, the processing is enabled by loading the rearrange table necessary for decompressing the image data from the rearrange table data file stored in the HDD into the decompression unit.
[0014]
FIG. 2 shows an embodiment of a system related to local storage processing in which the rearrange table is stored as a file in the HDD.
FIG. 2 shows a main part related to such local storage processing. The HDD 501 (the storage unit 402 in FIG. 1), the main storage device 505 (the memory built in the memory control unit 409 in FIG. 1), and the ROM 502 (in FIG. 1). It is the block diagram which showed the mutual relationship of ROM in the system control part 405.
The latest rearrange table data 503 normally used in the compression / decompression unit of the memory control unit 409 exists as a file on the ROM 502 built in the system control unit 405, and the ROM 502 is set as a default setting when the digital copier 100 is turned on. The rearrange table data 503 is mapped to the work memory area (not shown) of the memory control unit 409 and used for processing in the compression / decompression unit.
The HDD 501 used for the local storage of the input image is divided into an area 508 used by the local storage and an area 507 used by the operating system for controlling the digital copying machine 100, and memory access is controlled for each data. This is performed by the unit 409 or the system control unit 405.
[0015]
FIG. 3 is a flowchart relating to the storage process of the rearrange table in the HDD in the above-described system.
In this process, a file name using table identification information (generation number attached to the table) is also attached to the rearrange table used for data compression by the rearrange process performed when an image is stored in the HDD. The table is stored in the HDD, each generation table is managed, and a table suitable for restoring (decompressing) the stored image is prepared so as to eliminate the inability to restore.
The procedure of this process will be described with reference to FIG. First, the generation number added to the rear range table is acquired from the file of the rear range table data 503 stored in the ROM 502 built in the system control unit 405 as default setting data when the power is turned on (S31).
Next, the generation number obtained by the process of step S31 is added to a predetermined file name, thereby creating a file name for storing the rearrange table data 503 stored in the ROM 502 in the HDD 501 (S32). With the generation number of the file name created here, it becomes possible to know the generation of the rearrange table without referring to the contents of the file of the table data 503. Thereafter, the rearrange table data 503 stored in the ROM 502 is stored in the HDD 501 with the file name created in step S 32. At this time, the table data 503 is stored in the operating system area 507 of the HDD 501. On the other hand, the compressed image data is stored in the local storage area 508 of the HDD 501, and this image data is stored with the generation number of the rearrange table used at the time of compression.
[0016]
In the flow of FIG. 3, when the rearrange table data 503 is stored in the HDD 503, an attempt is made to open a file in which the file name of the rearrange table data 503 stored in the HDD 503 is written, and the file created in step S <b> 22 is included therein. It is checked whether a file having the same name as the file name exists (S33).
As a result of the check, if a file with the same name already exists in the operating system area 507 (S33-YES), the storage processing is terminated assuming that the same generation of rearrange table data exists. On the other hand, if a file with the same name does not exist (S33-NO), it is determined that rear-range table data of the same generation as the rear-range table data 503 in the ROM 502 built in the system control unit 405 is not stored in the HDD 501, and the rear-range table Data 503 is stored in the operating system area 507 of the HDD 501 (S34).
[0017]
FIG. 4 is a flowchart relating to the stored image restoration (decompression) process that enables the rearrange table setting to be changed in the above-described system.
In this process, the setting of the rearrange table applied to the stored image is made the same as that at the time of compression so that the decompressed image cannot be restored. As a premise for performing the processing at the time of restoration, the processing shown in the above-described embodiment relating to management of the rearrange table used at the time of storage (compression), that is, the operating system area 507 of the HDD 501 of the used rearrange table is used. And the use table generation number must be assigned to the stored image.
A processing procedure at the time of restoration (decompression) will be described with reference to FIG. First, when printing an image stored in the local storage area 508 of the HDD 501, the stored image data is temporarily stored from the local storage area 508 to the Store Memory on the main storage device 505 (the memory built in the memory control unit 409 in FIG. 1). It takes out to the area | region 506 (S41). After being extracted, the compressed image data on the Store Memory area 506 acquires the table generation number added to the image as the information of the rearrange table used at the time of compression held there (S42).
[0018]
Thereafter, when decompressing the image data, the rearrange table mapped to the work memory area (not shown) of the memory control unit 409 (usually the latest generation table rearrange table data 503 stored in the ROM 502 is activated. The generation number of the rearrange table used when the compressed image data is compressed is compared with the generation number (which is sometimes set by default) (S43).
As a result of the comparison, if the generation numbers of the rearrange table are different (S43—mismatch), the image data taken out for restoration (decompression) is a rearrange of a generation older than the latest rearrange table normally used. Based on the table generation number added to the extracted stored image, the table generation number is added to the file name, and the table of each generation stored in the operating system area 507 of the HDD 501 is determined. Search the file and map the rearrangement table data of the same generation number from the stored rearrangement table data on the work memory to change the setting table to a table that matches the image to be restored (expanded) (S44).
Next, by using the rearrange table whose setting has been changed, image data is decompressed (S45), and the process is terminated.
On the other hand, if the generation number of the rearrange table is the same as the comparison result of step S43 (S43-match), the image data taken out for restoration (decompression) is the latest rearrange table that is normally used. The image data is decompressed by immediately using the currently set rearrange table without changing the setting in step S44 (S45), and the process ends.
[0019]
【The invention's effect】
(1) Effects corresponding to the inventions of claims 1 to 3
Various conversion matrixes (tables) set for use in rearrange processing of binary images are stored, and the conversion matrix of the type used when compressing each stored image is used as the expansion means, and the type of conversion matrix used during compression is stored . A conversion matrix that is set in the expansion means by managing a conversion matrix that is set so that the conversion matrix having the same generation identification information as the conversion matrix is extracted from the data storage means and can be used by the expansion means. Even if the type of generation (for example, generation) changes, it is possible to take out a conversion table suitable for decompression (decompression) of a compressed image and change the setting. The conventional problems that could not be adapted to the difference can be solved.
In addition, the type information of the conversion matrix is stored in the data storage unit in association with each stored image, and the type of conversion matrix stored in association with the image when each stored image is expanded can be set in the expansion unit. It is possible to simplify the process for managing the conversion matrix used at the time of restoration (decompression), and to easily carry out the invention.
(2) Effect corresponding to invention of claim 4 In addition to the effect of (1) above, the data storage means is a storage means provided with a storage medium detachable from the image forming apparatus . For example, it is possible to employ a large-capacity storage unit such as an HDD, and it is possible to use data created by another image forming apparatus, thereby achieving high performance of the image forming apparatus.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram showing a digital copying machine as an embodiment relating to an image forming apparatus of the present invention.
FIG. 2 shows an embodiment of a system related to local storage processing for storing a rearrange table in a HDD as a file.
FIG. 3 is a flowchart related to a storage process of a rearrange table in the HDD performed when power is turned on.
FIG. 4 is a flowchart related to a stored image restoration (decompression) process in which a rearrange table setting can be changed.
[Explanation of symbols]
100: Digital copier, 200 ... Reading section,
300: Image forming section,
401... Image processing unit (IPU: image processing unit),
402: Storage unit, 405 ... System control unit,
406 ... operation unit, 409 ... memory control unit,
501: HDD (Hard Disk Drive),
502 ... ROM, 503 ... rearrange table data,
505: Main storage device.

Claims (4)

Compression means for compressing the dithered binary image through a rearrange process using a conversion matrix, data storage means for storing the compressed image, and an image extracted from the data storage means for converting the conversion matrix An image forming apparatus including an expansion unit that expands to an original binary image using the image forming apparatus,
Various conversion matrices set for use in rearrange processing of binary images are stored in the data storage means, and the conversion matrix has the same generation identification information as the type of conversion matrix used for compression when decompressing each stored image image forming apparatus characterized by a with a conversion matrix management unit Ru set Teisu for use in the expanding unit is taken out from the data storage means. 2. The image forming apparatus according to claim 1, wherein the conversion matrix management means stores the type information of the conversion matrix used for the rearrangement processing of the binary image at the time of image accumulation in association with each accumulated image in the data accumulation means. and an image forming apparatus is characterized in that the set Teisu so that the decompression means a transformation matrix type accumulated in association with the image at the time of expansion of the stored image.   3. The image forming apparatus according to claim 2, wherein when the stored image is expanded, the conversion matrix management unit checks a match between the conversion matrix set in the expansion unit and the conversion matrix associated with the stored image, An image forming apparatus characterized in that, when there is a mismatch, the setting is changed to the conversion matrix type stored in association with the stored image. 4. The image forming apparatus according to claim 1, wherein the data storage unit is a storage unit including a storage medium that is detachable from the image forming apparatus.

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