JP2000134478A - Image data encoding and decoding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to store more images by the device which encodes a color image by components of R, G, and B, Y, M, C, and K, etc., and stores the components on storage media assigned by the components for electronic sorting. SOLUTION: The device is equipped with a converting means (image process part) which converts image data into (n) components more than two, (n) encoding parts 401 to 403 which compress image data by the converted components, (n) hard disks 601 to 603 which store the codes by the compressed components, an input signal switching part 501 which switches the correspondence between the codes by the components and the hard disks 601 to 603 by images, (n) decoding parts which expand and reproduce the codes of the components stored in the hard disks 601 to 603 by the images, and an output signal switching part which switch the correspondence between the components stored in the hard disks 601 to 603 and the decoding parts by the images.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of storing original image information in an internal storage device in the reading order, and after reading all the originals, outputting the image data stored therein in the reading order, and repeating the output operation for a desired number of copies. Accordingly, the present invention relates to an image forming system such as a digital copying machine that realizes an electronic sort function.

[0002]

2. Description of the Related Art An image forming apparatus such as a digital copying machine having an electronic sort function reads an original, accumulates the image data in the apparatus, and outputs the image data stored therein in a read order in a desired number of copies. By repeating, sorting of the copy output is realized. Therefore, an image forming apparatus having an electronic sorting function has advantages over a conventional copying machine that mechanically sorts, such that a document is read only once and a mechanical part for sorting is not required. Generally, a large-capacity storage medium such as a hard disk is used as an image storage device, but in recent years, the speed of image input / output of a copying machine has become extremely high, particularly when a color image with a large amount of data is handled. If the image data is stored in one hard disk as it is, the speed of the hard disk becomes a bottleneck, and the speed performance of the copier at the time of electronic sorting is reduced. Therefore, a method is considered in which one hard disk is assigned to each component of color image data, such as RGB, YMCK, etc., and input / output is performed. In order to accumulate a large number of images on the hard disk, an encoding unit (decoding unit) is provided before the input / output of the hard disk as shown in FIG. 16, and each component is encoded using a multi-valued image compression algorithm such as JPEG. It is effective to reduce the amount of data and store it. However, in the case of compressing images separately for RGB, for example, if the density change of the read image data continues in the relationship of R component> G component> B component, an image having a large density change has a low compression ratio, as shown in FIG. As a result, the hard disk area allocated to the R component is no longer available, and image data cannot be stored, even though there is still room in the head of another hard disk, and the free area is wasted. Although a large number of conventional techniques relating to electronic sorting have been proposed as disclosed in Japanese Patent Application Laid-Open No. 05-103171, there is no such technique as described above having a hard disk for each of RGB which is unique to a color image.

[0003]

The problem to be solved by the present invention is as follows. According to the first and second aspects of the present invention, a color image is encoded for each component such as RGB, YMCK, etc., and stored in a storage medium assigned for each component to perform electronic sorting. By sequentially switching the storage destination of the code in the storage medium for each image, the code can be stored in an equal amount in each storage medium as compared with the case where the component is fixed, and a larger number of images can be stored. Be able to do it. According to the first, third and fourth aspects of the present invention, a color image is encoded for each component such as RGB and YMCK, and stored in a storage medium assigned for each component to perform electronic sorting. By switching the storage destination of the code for each component to the storage medium based on the current free space of the storage medium and the result of the code amount for each component for each image, the storage destination for each storage medium is compared with the case where the component is fixed. A code can be stored in an equal amount, so that a larger number of images can be stored. According to the first, third, and fifth aspects of the present invention, a color image is encoded for each component such as a luminance component and a color component such as YCrCb, and stored in a storage medium assigned for each component to perform electronic sorting. In the device, the storage destination of the code for each component in the storage medium is switched based on the current free space of the storage medium and the nature of the coding efficiency of each component for each image, so that each storage medium is compared with the case where the component is fixed. The code can be stored in a uniform amount, and a larger number of images can be stored.

[0004]

According to a first aspect of the present invention, there is provided an image input means for inputting a color document image as image data one page at a time. conversion means for converting into n components;
N encoding means for respectively compressing the converted image data for each component, n code accumulating means for storing the code for each compressed component, and a code for each component and accumulating the same First signal switching means for switching the correspondence with the n code storage means for each image, and n number of codes for expanding and reproducing the code of each component stored in the n code storage means for each image And a second signal switching means for switching the correspondence between the code of each component stored in the n code storage means and the decoding means for each image. According to a second aspect of the present invention, in the image data encoding / decoding apparatus according to the first aspect, an image data managing unit that assigns a number to each page of the image data input by the image input unit and manages the page. The image processing apparatus further includes a signal switching control unit that controls the first signal switching unit and the second signal switching unit by referring to the numbers of the images assigned by the image data management unit. According to a third aspect of the present invention, in the image data encoding / decoding apparatus according to the first aspect, a free capacity comparing means for comparing the size of the free capacity of the n code storage means, and the free capacity comparing means. And a signal switching control means for controlling the first signal switching means and the second signal switching means based on the result of the above. According to a fourth aspect of the present invention, in the image data encoding / decoding apparatus according to the first or third aspect, the signal switching control means for controlling the first signal switching means and the second signal switching means comprises: It is characterized by being controlled by the code amount of each component of the previously coded image in addition to the result of the free space comparison means. According to the fifth aspect of the present invention, in the image data encoding / decoding apparatus according to the first or third aspect, the n components converted by the conversion means are clearly different from the case of a luminance component and a color component. In the case where there is a characteristic that the code amount at the time of encoding has a difference, the signal switching control unit that controls the first signal switching unit and the second signal switching unit includes, in addition to the result of the free space comparison unit, It is characterized by being controlled by information on the difference in relative coding efficiency between components.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments. FIG. 1 is a block diagram of an image data encoding / decoding device showing an example of an embodiment of the present invention. The outline of the configuration and operation of the image data encoding / decoding device of the present invention will be described with reference to this block diagram. Main control unit 301
Is composed of a CPU, a ROM, a RAM and the like, and controls the entire copying apparatus including the encoding / decoding apparatus. In the operation unit 302, various operations and settings are performed by an operator. The automatic document feeder 303 is appropriately used as needed, and when a plurality of documents are set, the documents are conveyed one by one to the platen of the scanner 304 so that the scanner can read the documents one by one. The scanner 304 reads a document. The RGB image data signal from the scanner 304 is A /
Each of them is converted into an 8-bit digital signal by the D conversion unit 306. The image processing unit 306 performs image processing such as scaling and density adjustment. The recording unit 308 receives the image data from the image processing unit 306 and outputs a color copy image. The image storage unit 307 includes a storage device such as a memory and a hard disk. The image storage unit 307 can temporarily store the RGB image data from the image processing unit 306, read it out, and output it as a copy from the recording unit. The image storage unit 307
In order to reduce the data storage amount, the image processing apparatus has an encoding decoder that separately compresses RGB image data, stores the data as codes, decompresses the image data, and returns the image data. At the time of the sorting operation, the image data of all the pages of the read original is stored in the storage unit (hard disk) of the image storage unit 307, and then stored in the storage unit 308.
By copying the image data to the input order, all pages are copied and output, and these operations are repeated for the required number of copies.

Next, an image storage unit 30 which is a feature of the present invention.
7 will be described in more detail. As shown in FIG. 2, the image storage unit 307 encodes and stores the RGB image data for each component image. Which component code is input to which hard disk 601 to 603 can be selected by the input signal switching unit. As shown in the table of FIG. 3, there are three combinations of settings, namely, settings 1 to 3, in which the sign of each component is input to a different hard disk for each setting. The codes stored in the hard disks 601 to 603 from the encoding units 401 to 403 have an address management table corresponding to each of the hard disks 601 to 603 in the memory of the main control unit 301 as shown in FIG. Image numbers (images 0, 1, 2
..), And the write start address (A10, A
11...) Are stored. Also, according to the excessive number obtained by dividing the image number by 3, the setting of the input signal switching unit is changed as shown in FIG. By switching the hard disk of the storage destination of the code of each component of RGB each time one image is stored in this manner, each code of FIG. 17 in the case of the prior art is sorted as shown in FIG.
1 to 603 can secure a substantially equal free area. Therefore, it is possible to add a new image code to these empty areas. The code data thus accumulated is connected to decoding units 701 to 703 for each hard disk as shown in FIG. 7, and the main control unit 301 refers to the start address in the hard disk for each image number and outputs the data from the hard disk. Reading is performed, and the read code is decoded and returned to the bit plane image. At this time, the output image switching unit switches the connection for each component as shown in FIG. 5 according to the excessive number obtained by dividing the image number by 3 in the main control unit 301. Thus, according to the present invention,
Encode color image data for each RGB by electronic sorting,
By switching the hard disk that stores the codes of the RGB components in order for each image in the method of storing the codes for each RGB on separate hard disks, a uniform storage is provided for each hard disk as compared with the case where the storage destination is fixed for each RGB. A code can be stored in the quantity, and a larger number of images can be stored.

In the above example, the correspondence between the RGB components and the hard disk is switched by an excessive number obtained by dividing the image number by three. However, a method of switching this switching by the size of the free space of the hard disk is also effective. is there. In this case, first, as shown in FIG. 8, the code of the image 0 is stored in the hard disks 601 to 603 for each of the RGB components.
Here, since the free area of the hard disk (1) 601 becomes the smallest, it is expected that the code of the B component having the smallest code amount this time will also have the next smaller code amount. The main control unit 301 switches the setting of the input signal switching unit to the setting 2 in the table of FIG. That is, the setting is switched so that a code of a component expected to have a small code amount is assigned to the hard disk having the smallest free area every time an image of one page is accumulated. When the second image is stored according to this method, the code is stored as shown in FIG. When decoding an image from the hard disk, as shown in FIG. 10, a hard disk (HD) allocation management table in which the setting of the input signal switching unit is stored for each image in the memory of the main control unit 301 is shown. With this arrangement, the assignment of the hard disk to which the code is input for each image can be understood. At the time of decoding, the image can be decoded for each of the RGB components by switching the output signal switching unit of FIG. 7 with reference to this table.

As described above, according to the present invention, in a system in which color image data is encoded for each RGB by electronic sorting, and a code for each RGB is stored on a separate hard disk, one image is encoded, By changing the storage destination to encode and store the component expected to have the least code amount on the least hard disk,
As compared with the case where the storage destination is fixed every time, codes can be stored in equal amounts in each hard disk, and a larger number of images can be stored. It is generally known that when a color image is encoded, if the RGB components are converted into a luminance component and a color component before encoding, the redundancy between components is reduced and the compression ratio is improved. . A description will be given using Y, Cr, and Cb as an example of a color system of a luminance region component and a color component. Y, Cr and Cb can be calculated by the following equations. Y = 0.299R + 0.5865G + 0.1144B Cr = 0.4998R-0.4185G-0.0813B Cb = -0.1686R-0.3311G + 0.4997B Here, the Y component represents luminance, and the Cr and Cb components represent color. Represent.

FIG. 11 shows an embodiment in which the above color system conversion processing is used. This is obtained by adding the color system conversion units 1307 and 1309 to the configuration of FIG. 1, and the color system conversion unit (1) 130 before input to the image storage unit 1308.
In step 7, RGB → YCrCb conversion is performed.
8 in the color system conversion unit (2) 1309 at the subsequent stage.
Performs RGB conversion. Next, the image storage unit 1308 will be described. As shown in FIG.
The CrCb image data is encoded and stored for each component image. Which hard disk has the sign of which component
The input signal switching unit 03 can be selected by the input signal switching unit in accordance with the settings shown in FIG. When encoding is performed in this manner, the amount of information generally increases because the amount of information of the Y component, which is a luminance component, increases. If codes are initially stored at setting 1, as shown in FIG. )
601 has the least amount of free space. Since the code amount of the Y component is expected to always be the largest, the input signal switching unit 50 according to the setting of FIG.
By switching the setting of 1, the three hard disks can be used efficiently. As described above, according to the present invention, the color image data is converted into luminance and color components such as YCrCb by electronic sorting, encoded for each luminance and color component, and these codes are stored in separate hard disks. After encoding the image, the storage destination is changed so that the luminance component expected to have the largest code amount is encoded and stored in the hard disk having the largest free space, thereby storing the code for each luminance and color component. Compared to the case where the destination is fixed, codes can be stored in equal amounts in each hard disk, and a larger number of images can be stored.

[0010]

As described above, according to the present invention, the following excellent effects can be exhibited. According to the first and second aspects of the present invention, in a device for encoding a color image for each component such as RGB and storing it in a storage medium allocated for each component and performing electronic sorting, a code for each component is provided. By switching the storage destination in the storage medium in order for each image, the code can be stored in an equal amount in each storage medium as compared with the case of fixed component, and a larger number of images can be stored. it can. According to the present invention, a color image is encoded for each component such as RGB and stored in a storage medium allocated for each component to perform electronic sorting. By switching the storage destination of the code in the storage medium for each image based on the current free space of the storage medium and the result of the code amount for each component so far,
Compared to the case of fixed components, codes can be stored in equal amounts in each storage medium, and a larger number of images can be stored. According to the first, third and fifth aspects of the present invention, a color image is encoded for each component such as a luminance component and a color component such as YCrCb, and stored in a storage medium allocated for each component to perform electronic sorting. In the apparatus, the storage destination of the code for each component in the storage medium is switched for each image based on the current free space of the storage medium and the nature of the coding efficiency of each component, so that each storage is compared with the case where the component is fixed. The code can be stored in a uniform amount on the medium, and a larger number of images can be stored.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating an overall configuration of an image data encoding / decoding device according to the present invention.

FIG. 2 is a functional block diagram of an image storage unit shown in FIG.

FIG. 3 is a diagram showing a combination of which component code is input to which hard disk when RGB image data is encoded and stored for each component image.

FIG. 4 is an explanatory diagram showing an address management table corresponding to each hard disk.

FIG. 5 is a table showing the correspondence between the number of remainders obtained by dividing the image number by 3 and the setting of the input signal switching unit.

FIG. 6 is a diagram exemplifying a distribution state of each code to each hard disk.

FIG. 7 is a functional block diagram of an image storage unit shown in FIG.

FIG. 8 is a diagram exemplifying a state in which respective codes of RGB components of an image 0 are stored in different hard disks.

9 is a diagram exemplifying a state in which the respective codes of the RGB components of the image 1 are stored in separate hard disks following the state of FIG.

FIG. 10 is an explanatory diagram showing an HD management table.

FIG. 11 is a block diagram of an image data encoding / decoding device showing another example of the embodiment of the present invention.

12 is a functional block diagram of the image storage unit shown in FIG.

FIG. 13 is a diagram exemplifying a state in which each code of each component of YCrCb image data of image 0 is stored in a separate hard disk.

FIG. 14 is a diagram showing combinations of codes of which components are input to which hard disks when YCrCb image data is encoded for each component image and stored.

FIG. 15 is a diagram exemplifying a setting of an input signal switching unit that stores a Y-component code in a hard disk having the largest free area.

FIG. 16 is a functional block diagram of an image storage unit according to the related art.

FIG. 17 is a diagram exemplifying an accumulation state of each code of RGB components in each hard disk in the related art.

[Explanation of symbols]

304: scanner (image input unit), 306: image processing unit (conversion unit), 307: image storage unit (encoding unit),
308: main control unit (signal switching control means), 401 to
403: coding section (decoding means), 501: input signal switching section (first signal switching means), 601 to 603:
Hard disk (code storage unit), 701 to 703: decoding unit (second signal switching unit), 1304: scanner (image input unit), 1306: image processing unit (conversion unit), 1307: image storage unit (coding unit) ), 130
8: Main control unit (signal switching control means).

Claims (5)

[Claims] 1. An image input unit for inputting a color document image as image data one page at a time, a conversion unit for converting the image data into two or more n components, and image data for each of the converted components N encoding means for respectively compressing the codes, n code accumulating means for storing the code for each compressed component, n codes for each of the components, and n for accumulating the code
A first signal switching means for switching the correspondence with the number of code storage means for each image, and n number of reproduction means for expanding and reproducing the code of each component stored in the n code storage means for each image. Image data comprising: signal means; and second signal switching means for switching, for each image, the correspondence between the code of each component stored in the n code storage means and the decoding means. Encoding decoder. 2. An image data encoding / decoding apparatus according to claim 1, wherein said image data management means assigns a number to each page of the image data inputted by said image input means and manages said page. Image data encoding / decoding comprising signal switching control means for controlling the first signal switching means and the second signal switching means with reference to the numbers of the respective images given by the means. apparatus. 3. An image data encoding / decoding apparatus according to claim 1, wherein said n number of code accumulating means compares a free capacity with a free capacity comparing means, and based on a result of said free capacity comparing means. The first signal switching means and the second signal switching means;
And a signal switching control unit for controlling the signal switching unit. 4. The image data encoding / decoding device according to claim 1, wherein said first signal switching means and said second signal switching means are connected to each other.
The signal switching control means for controlling the signal switching means is controlled by the code amount of each component of the previously coded image in addition to the result of the free space comparison means. Compound decoding device. 5. The image data encoding / decoding apparatus according to claim 1, wherein said n components converted by said conversion means are clearly encoded as in the case of a luminance component and a color component. In the case where the code amount has a property of being different, the signal switching control means for controlling the first signal switching means and the second signal switching means has a relative capacity between the components in addition to the result of the free space comparison means. An image data encoding / decoding apparatus controlled by information on a difference in encoding efficiency.