JP2000217003A - Coding system and decoding system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain coding processing with a high compression rate and at a high speed without the need for addition of a special processing or unit to an input and output sections of coders even when image information is coded by a coding system with a high compression rate in the case that the coders are used to apply parallel coding processing. SOLUTION: This coding system 10 is provided with a coding section 12 having coders, an image distribution section 11 that uniformly distributes a received image to the coders, and a code generating section 13 that generates one code stream among plural codes outputted from the coding section 12. While the received image is uniformly distributed to the coders, the coders conduct processing in parallel and one code stream is generated from the codes outputted from the coders according to a prescribed rule to process the coding.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an encoding device having a plurality of encoders and a decoding device having a plurality of decoders.

[0002]

2. Description of the Related Art With the progress of OA in offices and the like in recent years, devices for handling digital images represented by digital copiers and facsimile machines have become widespread.
In these devices, the amount of information to be handled has been remarkably increased due to the improvement in resolution and the amount of information per pixel, and there is an inevitably demand for faster data processing. To speed up the data processing, it is important to speed up the data processing itself, but it is also particularly necessary to reduce the time spent for transferring large-volume data having a large amount of information.

[0003] Therefore, as one of the methods for shortening the delivery time of large-capacity data, a method of efficiently compressing the data itself to reduce the amount of transfer data has attracted attention. As such a data compression method, there is an MH, MR, MMR coding method conventionally used in facsimile (MH = Mod).
ifif Huffman, MR = Modified
READ, MMR = Modified MR). According to any of these encoding methods, text images can be encoded at a high compression ratio, but a halftone image such as a photographic image can hardly be compressed. is there.

On the other hand, as an encoding method capable of efficiently compressing any image, for example, Japanese Unexamined Patent Publication No.
There is an entropy coding method represented by the arithmetic coding method described in Japanese Patent No. 311045. Examples of the arithmetic coding system include ITU-T (International Telegraph and Telephone Consultative Committee) and I.T.-T, which determine facsimile communication standards.
QM-Code standardized by SO (International Organization for Standardization)
r (ISO / IEC11544 (JBIG), Pro-
Gressive bi-level image c
impression (JBIG)). This QM
According to -Coder, it is possible to encode image information at a compression ratio close to the theoretically limitable compression value. QM
The arithmetic coding method represented by -Coder predicts and encodes a target pixel, and a high predictive predictive value improves a compression ratio.

[0005]

By the way, when the QM-coder, which is an arithmetic coding method, and the MH method, which is a run-length coding method, are compared, the coding processing speed of the MH is much higher. Therefore, even if the image can be efficiently compressed by the QM-coder, as a whole,
Processing time is longer than in the MH method. for that reason,
Even if the compression efficiency is somewhat low, M
H and the like, the overall processing time is shorter,
The high compression rate provided by the M-coder cannot be utilized.

On the other hand, as one of methods for performing high-speed encoding processing while making use of such a high compression rate by QM-coder, a method of performing parallel processing using a plurality of encoders is considered. According to this method, the encoding speed as a whole can be improved as the number of processes performed in parallel increases. But,
In such parallel processing, the problem is how to input and output to a plurality of encoders. When the speed is improved by the above method, generally, at the time of input, the image must be divided in advance according to the number of encoders, and the divided images must be input in parallel. Further, at the time of output, the codes are output independently by the number of encoders processed in parallel, so that these must be held as independent ones. These restrictions increase the complexity of input / output, and in addition, when configured with hardware, increase the cost such as an increase in I / O pins.

[0007] As a high-speed encoding process, there is a predictive encoding method. In this predictive coding method, when predicting the symbol of the pixel of interest, it is general to use the state of surrounding pixels. These surrounding pixels are called reference pixels,
In many cases, it is a pixel near the pixel of interest. However, when neighboring pixels are used as reference pixels, there is no problem as long as the processing is performed one pixel at a time. However, when processing is performed in parallel using a plurality of encoders, the processing speed depends on how to obtain the reference pixel position. There are restrictions. For example, if the pixel immediately to the left of the pixel of interest is the reference pixel, there is no problem because the pixel immediately to the left of the pixel to be processed at the time of encoding is already known, but the pixel immediately to the left of Cannot be started until the pixel of interest is decoded, and consequently, only one pixel at a time can be processed in parallel.

[0008] In addition, an encoder which encodes a binary image in 1-bit units such as a JBIG system used in a facsimile apparatus or a multi-value image which is an object such as a JPEG system is used for an encoder. There is an encoder that performs encoding in units of one byte. However, these encoders use a 1-bit unit or a 1-byte unit as a minimum processing unit, and it is impossible to perform encoding in a unit larger than this. If codes output from a plurality of encoders are created as they are in the order in which they were created, it becomes impossible to determine which code can be passed to which encoder at the time of decoding, and as a result, an image can be reproduced. Will be gone.

Further, when the code length is set to a byte unit in the above-described code generation processing, the code cannot be output unless all the codes output from the encoders are aligned in bytes. Therefore, the extra codes output from each encoder must be stored until the byte-length codes can be determined in all the encoders. In this case, if the output difference between the encoders is large, a large area for storing codes is required.

In order to reproduce an image at high speed from a code created by performing parallel processing by a plurality of encoders using the above-described encoding apparatus, a method of arranging decoders in parallel and performing parallel processing is conceivable. . According to this method, as the number of processes performed in parallel increases, the overall processing speed can be improved. However, this method cannot reproduce an image unless the input and output to the decoder are properly controlled.

Therefore, a first object of the present invention is to provide a method for performing encoding processing in parallel using a plurality of encoders, even when image information is encoded by a high compression rate encoding method. It is an object of the present invention to provide an encoding device that enables encoding processing at a high compression rate and at a high speed without adding any special processing or device to an input unit or an output unit of the encoder.

Further, a second object of the present invention is to provide a decoder for parallel decoding using a plurality of decoders without adding special control to the input and output sections of each decoder. ,
An object of the present invention is to provide a decoding device which enables a decoding process at a high speed.

[0013]

According to the first aspect of the present invention,
Image distributing means for receiving input image data and distributing it uniformly, and encoding means having a plurality of encoders for performing encoding processing in parallel on the image data distributed by the image distributing means And a code generating means for generating one code string by arranging a plurality of codes coded and output by the coding means according to a predetermined rule. Thereby, the first object is achieved.

According to a second aspect of the present invention, the encoding means creates surrounding pixel information of a pixel to be encoded with a template, and then predicts a target pixel from the surrounding pixel information created with the template. Probability is determined by a probability evaluator, and prediction coding means for performing arithmetic coding in an arithmetic coder based on the determined prediction probability is used.Reference pixels used for obtaining the prediction probability are simultaneously processed in parallel. The first object is achieved by providing an encoding device according to claim 1, wherein pixels are not used.

According to a third aspect of the present invention, in accordance with the first aspect of the present invention, there is provided the encoding apparatus according to the first aspect, wherein the image allocating means sequentially allocates the images in accordance with a minimum processing unit of the encoder. Achieve the first objective.

According to a fourth aspect of the present invention, the code generation means converts the codes output from the plurality of encoders of the coding means in a predetermined code length unit and in a predetermined order. The first object is achieved by providing an encoding device according to claim 1, wherein the encoding device is created.

According to a fifth aspect of the present invention, when the difference between the code lengths output from the respective encoders of the encoding means becomes larger than a predetermined code length, the code having the shortest code length is used. The first object is achieved by providing an encoding apparatus according to claim 4, wherein the encoding is performed by inserting a meaningless dummy code.

According to a sixth aspect of the present invention, there is provided a code distributing means for receiving an input code and distributing the same uniformly, and a plurality of decoders for performing decoding processing on the code distributed by the code distributing means in parallel. Decoding means comprising: a decoding means having: a plurality of image information strings output from the decoding means arranged in accordance with a predetermined rule to generate one reproduced image; The second object is achieved by providing an apparatus.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of an encoding apparatus and a decoding apparatus according to the present invention will be described below with reference to FIGS. FIG. 1 shows an encoding device (encoding unit 103) according to this embodiment as a facsimile device 1
It is a block diagram when it applies to 00. The facsimile apparatus 100 includes an image reading unit 101, an image processing unit 102, and an encoding unit 103 on the facsimile transmitting side, and includes a decoding unit 104 on the facsimile receiving side.
, An image processing unit 105, and an image output unit 106. The transmitting side of the facsimile and the receiving side of the other facsimile are connected via a transmission line 107 such as a telephone line. The image reading unit 101 reads a document on the transmission side (encoding side) using a CCD image sensor that is a photoelectric conversion element. The image processing unit 102 includes the image reading unit 10
A process for converting the image data read in step 1 into data suitable as data to be transmitted is performed.

The encoding unit 103 encodes the data processed by the image processing unit 102 and sends the encoded data to the transmission path 107. After receiving the encoded data from the transmission path 107, the decoding unit 104 decodes the encoded data. The image processing unit 105 performs image processing suitable for the output device on the decoded data. The image output unit 106 outputs the image data from the image processing unit 105 as a hard copy via a plotter or the like. Note that examples of image processing performed by the image processing unit 102 and the image processing unit 105 include resolution conversion or size conversion for a binary image, and color (color component) conversion for a multi-valued image including a color. Resolution conversion or size conversion is mentioned.

As an example of an encoding system used in the encoding unit 103 and the decoding unit 104, for a binary image, a MH, MR, MMR system generally used in a facsimile apparatus or a JBIG (Joint) using an arithmetic code is used. Bi-le
vel Image Coding Experts
Group) system, and for multi-valued images, JPEG (Joint Photo) using adaptive discrete cosine transform.
graphical Coding Experts G
loop) method. Here, a QM-coder (JBIG arithmetic encoder), which is one of the arithmetic coding systems, will be described with reference to FIG.

In the QM-coder, first, using the template 201, pixel information around pixels of image data to be encoded is created. After that, the probability estimator 202 determines the prediction probability of the target pixel from the surrounding pixel information created by the template 201. Then, arithmetic coding is performed by the arithmetic coder 203 based on the determined prediction probability. Note that the probability evaluator 202 performs a process of updating the probability based on information from the arithmetic encoder in order to make the prediction probability more accurate.

Next, an arithmetic coding method applied to the arithmetic encoder 203 will be described with reference to FIG. The arithmetic coding method is a conventional run-length coding method (MH, M
It is generally considered that the coding efficiency is better than R). In this arithmetic coding method, a corresponding section (binary decimal [0.0... 0, 0.1... 1]) on a number line of (0, 1) is unequal according to the occurrence probability of each symbol. The coordinates of the points included in the section obtained by dividing the target symbol sequence into corresponding subsections and repeating the division recursively at least can be distinguished from at least other sections by binary division. The code is expressed as a decimal number as it is.

Here, the concept of arithmetic coding will be described using the symbol sequence "0100" as an example. First, when encoding the first symbol, the entire section is divided into A (0) and A (1) according to the ratio of the occurrence probabilities of the symbols “0” and “1”. ) Is selected. Next, when encoding the second symbol, A (0) is further divided by the occurrence probability ratio of both symbols in that state, and A (01) is defined as a section corresponding to the generated symbol sequence.
Is selected. Encoding proceeds by repeating such division and selection processes. On the other hand, at the time of decoding, a process completely opposite to that of the encoding is performed, and the symbol is reproduced based on the binary decimal number indicated by the code. What is important here is the width of the number line when encoding the symbol, and if the width of the number line does not match at the start of encoding and at the start of decoding,
This means that symbols cannot be reproduced accurately. Normally, the width of this number line is set to 1 on both the encoding side and the decoding side.

Next, a basic configuration of the encoding device 10 according to the first embodiment will be described with reference to FIG. The encoding device 10 is an encoding unit 10 of the facsimile device 100 of FIG.
3 (encoding devices 20, 30, 40,
50 is the same). The encoding device 10 includes an image distribution unit 11, an encoding unit 12, and a code generation unit 13. The image sorting unit 11 sorts the input image information from the encoders 1 arranged in parallel in the encoding unit 12 to the encoders 4. The encoding unit 12 arranges the encoders 1 to 4 in parallel and encodes image information input from the image sorting unit 11. The code generation unit 13 generates one code string from the codes generated in parallel by the encoding unit 12 according to a predetermined rule.

Next, the overall operation of the encoding device 10 will be described. First, the image information is input to the image sorting unit 11 and divided according to a predetermined rule according to the number of parallel encoders at the next stage, and each image information is output. As an example of the division here, division into 1-bit units can be mentioned. The divided image information is simultaneously input to the encoding unit 12 in which the encoders are arranged in parallel, and each is independently encoded. In the encoding device 10 of this example, the number of encoders arranged in parallel is four. Encoder 1 to Encoder 4
Are different in code length, and the generated codes are input to the code generation unit 13. The code generation unit 13 creates one code string from code strings input in parallel based on a predetermined rule. As an example of creating a code string, there is a method of sequentially arranging the codes created by the respective encoders in byte units into a code string. Code information is created for image information by such a processing procedure.

According to the first embodiment, a process is performed in parallel by a plurality of encoders while distributing input image information to a plurality of encoders according to a predetermined rule, and output from the plurality of encoders is performed. 1 according to a predetermined rule
One code string is created. As a result, when parallel encoding is performed using a plurality of encoders, high-speed processing can be performed as before, without adding special processing or equipment to the input and output sections of each encoder. Become. In the first embodiment, the number of encoders arranged in parallel is four, but the number is not limited. However, although the encoding process can be sped up as the number of encoders increases, the encoding process may be complicated.

Next, an encoder used in the encoding apparatus according to the second embodiment will be described with reference to FIGS. The basic configuration of the encoding device according to the second embodiment is the first configuration.
The configuration is the same as the basic configuration of the encoding device according to the embodiment, and thus will not be described here. FIGS. 5 and 6 are diagrams for explaining an effective use method of the template 201 in the arithmetic coding method using the arithmetic encoder shown in FIG. 2 as an encoder. 5 and 6, the position of surrounding pixel information used in predictive coding is shown, and the state of the surrounding pixel represented by “○” is predicted as information for the pixel of interest represented by “x”. Information has been created.

In the method using the template shown in FIG. 5, since the surrounding pixel information of the current line having the target pixel is not used, high-speed processing can be performed without being affected by the state of the previous pixel even in the parallel processing. is there. On the other hand, in the method using the template shown in FIG. 6, four encoders are parallelized, and templates (a), (b), (c), and (d) composed of different surrounding pixel information in encoders 1 to 4 respectively. ), But none of the image information itself to be processed in parallel is used as surrounding pixel information, so that high-speed processing is possible.

In FIGS. 5 and 6, the processing by the template shown in FIG. 5 is simpler, but the processing by the templates (a), (b), (c) and (d) shown in FIG. In many cases, the coding efficiency is slightly lower than the processing. As described above, according to the second embodiment, when a template is used at the time of encoding in an arithmetic coding method, the reference pixel of the template does not use the pixel state of the pixel position to be processed at the same time. The processing can be executed at high speed.

Next, an encoding device 20 and an encoding device 30 according to the third embodiment will be described with reference to FIGS. As shown in FIG. 7, the encoding device 20 includes an image sorting unit 21, an encoding unit 22, and a code generation unit 23. On the other hand, as shown in FIG.
Includes an image distribution unit 31, an encoding unit 32, and a code generation unit 33. The operations of the code generation unit 23 and the code generation unit 33 are the same as the operation of the code generation unit 13 of the first embodiment, and thus description thereof will be omitted. The encoders arranged in parallel in the encoding unit include an encoder 22 composed of a binary encoder as shown in FIG. 7 and an encoder 32 composed of a multi-level encoder as shown in FIG. And divided into

Here, the unit of the encoding process in the case of FIG. 7 is a bit, while the unit of the encoding process in the case of FIG. 8 is a byte. Therefore, unless image information is input for each encoding processing unit, an extra storage unit for storing an extra part is required. However, in the third embodiment, the image sorting unit 21 or the image sorting unit 31 performs sorting in units of bits in the case of a binary encoder, and performs assignment in units of bytes in the case of a multi-level encoder. By such processing, high-speed encoding can be realized with a lean configuration. Third
According to the embodiment, considering the minimum processing unit of the encoder,
Even if the encoder of the encoding unit is changed by performing the image distribution processing according to the minimum processing unit of the encoder, it is possible to always achieve highly efficient encoding by changing the distribution pixel unit corresponding to it. Become.

Next, an encoding device 40 according to a fourth embodiment will be described with reference to FIGS. As shown in FIG. 9, the encoding device 40 includes an image distribution unit 41, an encoding unit 42, and a code generation unit 43. The operations of the image sorting unit 41 and the encoding unit 42 are the same as those of the image sorting unit 1 described above.
1 and the operation is the same as that of the encoding unit 12, and the description is omitted here. The code generation unit 43 creates a code in which the codes output from the respective encoders are arranged for each fixed code length shown in FIG. 10 from the code strings input in parallel. According to such a code string, it is easy to distribute codes at the time of decoding. Further, since there is no useless portion for converting codes input in parallel into one code string, a code string can be created without reducing efficiency.

According to the fourth embodiment, the output code is converted into a predetermined code length unit (eg, byte unit).
By creating codes in a predetermined order (for example, in the order of encoders), it is possible to pass the codes to an appropriate decoder at the time of decoding, and to reproduce image information without error.

Next, an encoding device 50 according to a fifth embodiment will be described with reference to FIGS. As shown in FIG. 11, the encoding device 50 includes an image sorting unit 51,
An encoding unit 52 and a code generation unit 53 are provided. The operation of the image sorting unit 51 is the same as the operation of the image sorting unit 11, and a description thereof will be omitted.

In the fourth embodiment shown in FIGS. 9 and 10, a code string can be created without lowering the coding efficiency. However, an extra code string is input until each of the code strings input in parallel has a predetermined length. The code string must be stored. Therefore, in the fifth embodiment, although the coding efficiency is slightly lowered, in order to solve the problem of the storage area for the extra code string, the stored code length is set to be smaller than the predetermined storage length. When it becomes long, a code string is created using a code that has no meaning, and the setting is made so as to output.

In the fifth embodiment, for example, as shown in FIG. 12, the output of the encoder 2 provided in the encoder 52 has not yet reached a certain length, and the output of the encoder 1 and the encoder have already been output. Since the output of No. 4 is stored four times as long as a certain length, a code string is created using the code corresponding to the encoder 2 as a dummy code. Here, the meaningless code (dummy code) is a code that never appears in a code string, and if such a code is found during decoding, it is ignored. Become.

According to the fifth embodiment, since a certain encoder cannot generate a code having a predetermined code length, the code length output by another encoder becomes longer than a predetermined length. In this case, by inserting a meaningless code string into the undecided code string and generating a code, and outputting the code, high-speed processing can be performed without increasing the area for storing the code.

Next, a decoding device 60 according to a sixth embodiment will be described with reference to FIG. It should be noted that the decoding device 60 is the decoding unit 10 of the facsimile device 100 of FIG.
4 applies. As shown in FIG. 13, the decoding device 60 includes a code distribution unit 61, a decoding unit 62, and an image generation unit 63. The code distribution unit 61 distributes the input code information for the decoders arranged in parallel. The decoding unit 62 arranges decoders for reproducing images in parallel, and performs decoding from input code information. The image generator 63 creates one playback image from the image information sequence created in parallel.

The overall operation of converting the code information into image information by the decoding device 60 configured as described above will be described. First, code information is input to the code distribution unit 61. In this code distributing unit 61, division is performed according to the same rule as at the time of encoding according to the number of parallel decoders in the next stage.
Each code information is output. The divided code information is simultaneously input from the decoders 1 arranged in parallel to the decoding unit 62 composed of the multiplexer 4, and the decoding processing is performed independently of each other. The image information created by each of the decoders 1 to 4 is input to the image generator 63. At the time of encoding from the image information sequence input in parallel, the image generation unit 63 performs the reverse connection according to the same rule as the rule distributed by the image distribution units 11, 21, 31 to generate reproduced image information.

According to the sixth embodiment, a decoding process is performed in parallel by a plurality of decoders while distributing an input code to a plurality of decoders according to the rules for creating codes at the time of coding. Then, by creating one reproduced image from the image information sequence output from a plurality of decoders, high-speed processing can be performed without adding special control to the input unit and output unit of each decoder. Becomes possible.

The case where the embodiment according to the present invention is applied to the facsimile apparatus 100 has been described above.
The embodiments according to the present invention are not limited to these, and the present invention can be applied to, for example, digital copiers and digital multifunction peripherals.

[0043]

According to the first aspect of the present invention, an input image is distributed in parallel by a plurality of encoders while equally distributed to the plurality of encoders, and an encoding process is performed. Since one code string is created from predetermined codes according to a predetermined rule, coding processing can be performed at a high compression rate and at a high speed.

According to the second aspect of the present invention, when the encoding means is the prediction encoding means, the reference pixels used for obtaining the prediction probability do not use pixels that are processed in parallel at the same time. Encoding processing can be performed at a high compression rate and high speed.

According to the third aspect of the present invention, since the pixel distributing means sequentially distributes the images in accordance with the minimum processing unit of the encoder, the encoding process can be performed at a high compression rate and at a high speed.

According to the fourth aspect of the present invention, the code generation means generates the codes output from the plurality of encoders in a predetermined code length unit and in a predetermined order. Encoding processing can be performed at a high compression rate and a high speed.

According to the fifth aspect of the present invention, when the difference between the code lengths output from the respective encoders is larger than a predetermined code length, the code having the shortest code length has no meaning. By performing code creation by inserting a missing code, encoding processing can be performed at a high compression rate and at a high speed.

According to the sixth aspect of the present invention, a decoding process is performed in parallel by a plurality of decoders while distributing an input code to the plurality of decoders, and one image data sequence is output from the plurality of decoders. By creating one reproduced image, decoding processing can be performed at high speed.

[Brief description of the drawings]

FIG. 1 is a block diagram when an encoding device is applied to a facsimile device.

FIG. 2 is a block diagram illustrating an arithmetic coding method.

FIG. 3 is a diagram for explaining an effective method in an arithmetic coding method according to a second embodiment.

FIG. 4 is a block diagram illustrating an encoding device 10 according to the first embodiment.

FIG. 5 is a diagram for explaining an effective method in the arithmetic coding method according to the second embodiment.

FIG. 6 is a diagram for explaining an effective method in the arithmetic coding method according to the second embodiment.

FIG. 7 is a block diagram illustrating an encoding device 20 according to a third embodiment.

FIG. 8 is a block diagram illustrating an encoding device 30 according to a third embodiment.

FIG. 9 is a diagram for describing an encoding device 40 according to a fourth embodiment.

FIG. 10 is a diagram for describing an encoding device 40 according to a fourth embodiment.

FIG. 11 is a block diagram illustrating an encoding device 50 according to a fifth embodiment.

FIG. 12 is a diagram for describing an encoding device 50 according to a fifth embodiment.

FIG. 13 is a block diagram illustrating a decoding device 60 according to a sixth embodiment.

[Explanation of symbols]

 10, 20, 30, 40, 50 Encoding device 11, 21, 31 Image distribution unit 12, 22, 32, 42, 52 Encoding unit 13, 23, 33, 43, 53 Code generation unit 60 Decoding device 61 Code Distributing unit 62 Decoding unit 63 Image generating unit 101 Image reading unit 102 Image processing unit 103 Encoding unit 104 Decoding unit 105 Image processing unit 106 Image output unit

Claims (6)

[Claims] An image distributing means for receiving input image data and distributing it uniformly, and a plurality of encoders for performing encoding processing on the image data distributed by the image distributing means in parallel And a code generating means for generating a single code string by arranging a plurality of codes coded and output by the coding means according to a predetermined rule. Device. 2. The encoding means creates surrounding pixel information of a pixel to be encoded, and then determines a prediction probability of a target pixel from a surrounding pixel information created by a template by a probability evaluator. Prediction coding means for performing arithmetic coding with an arithmetic coder based on the calculated prediction probabilities, wherein reference pixels used for obtaining the prediction probabilities do not use pixels processed in parallel at the same time. Item 7. The encoding device according to Item 1. 3. The encoding apparatus according to claim 1, wherein said image distribution unit sequentially distributes images according to a minimum processing unit of an encoder. 4. The code generating means generates codes output from a plurality of encoders of the coding means in a predetermined code length unit and in a predetermined order. The encoding device according to claim 1, wherein 5. A dummy code meaningless for a code having the shortest code length when a difference between code lengths output from the respective encoders of the coding means becomes larger than a predetermined code length. 5. The encoding apparatus according to claim 4, wherein the encoding is performed by inserting a symbol. 6. A code distribution means for receiving an input code and uniformly distributing the code, and a decoding means having a plurality of decoders for performing decoding processing in parallel on the code distributed by the code distribution means. An image generating means for generating one reproduced image by arranging a plurality of image information sequences output from the decoding means according to a predetermined rule.