JPH09200534A - Image encoder/decoder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image encoder/decoder with which the code data of interleave format composed of plural components can be encoded and decoded at high speed. SOLUTION: Image data L1 *, L2 *... inputted to an encoding/decoding part 1 are encoded by the encoding/decoding part 1, packed and made into bit data CL1 , CL2 .... A transforming part 4 detects the end of a block while decoding a bit sequence and segments the bit sequence CL1 for which the data L1 * are encoded. When the CL1 is segmented, a bit sequence Ca1 , for which data a1 * are encoded, is similarly segmented and linked to the CL1 . Next, a bit sequence Cb1 is similarly linked and by linking code data for each block while successively repeating this operation, the data can be transformed into interleave format.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image coding apparatus, and more particularly to an image coding / decoding apparatus for coding or decoding a variable length code composed of a plurality of components.

[0002]

2. Description of the Related Art Since a digital image has a large amount of information, its redundancy is normally used for data compression and transfer or recording. As a typical example, there is a standardized system such as an MH / MR / MMR system for a binarized image. In recent years, for more multi-valued images, JPEG
(Joint Photographic Expert
The coding method called tGroup) has been standardized.
This encoding method is based on a plurality of components (for example, RGB and YM).
Since it can handle CK), it can be said that the encoding method is suitable for handling a color image.

Although there are several modes in the JPEG encoding system, a system based on DCT is often used in which one pixel called a baseline is represented by 8 bits. In addition, there is a method called an interleave format for representing a plurality of components in the baseline. This system is a system in which Huffman coding is alternately performed for each block and expressed as one code. In this method, when the signals of the respective components input at the same time using a CCD or the like are encoded, or when the decoded image data is output by a single scan like a printer, a plurality of components are simultaneously output. There is an advantage that the system can be configured without having one page of image data.

However, since each block is represented by a variable length code, it has been impossible to code or decode each component in parallel. Therefore, as a circuit configuration corresponding to the interleave format with such a baseline, "Mitsubishi Technical Report" Vol. 166, No3 (1
994). This method is D
Interleave format is supported by alternately processing CT operation, quantization operation, Huffman code, and Huffman decoding for each component for each block.
However, there is a problem that high-speed operation cannot be realized because the processes are performed alternately.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and is an image in which coded data of an interleaved format composed of a plurality of components can be coded and decoded at high speed. It is an object to provide an encoding / decoding device.

[0006]

According to a first aspect of the present invention, there is provided an image encoding / decoding device for encoding an image including a plurality of components into a variable length code for each block or for decoding an image from the variable length code into an image. , A plurality of encoding / decoding means for performing encoding and decoding, and a converting means for mutually converting the code of each component and the interleave format,
The conversion means is characterized in that conversion is performed on the code of the conversion destination based on the information obtained by decoding the code of the conversion source.

According to a second aspect of the present invention, in the image encoding / decoding apparatus according to the first aspect, the converting means selects the encoding / decoding means as an input / output destination of the code of each component. And block end detecting means for decoding the received code to detect the block end, and control means for switching the selecting means according to the block end detected by the block end detecting means.

According to a third aspect of the present invention, in the image encoding / decoding apparatus according to the first aspect, the encoding / decoding means processes a code including a marker, and the converting means includes each component. Selecting means for selecting the encoding / decoding means to be the input / output destination of the code, block end detecting means for decoding the received code to detect the block end, and marker detecting means for detecting the marker from the received code. A marker processing means for adding a marker to a code and outputting it to the selecting means when the marker is detected by the marker detecting means or deleting the marker from the code and outputting the marker to the outside; It has a control means for switching the selection means according to the end of the block.

[0009]

FIG. 1 is a block diagram showing an example of an embodiment of the present invention. In the figure, reference numerals 1, 2, and 3 are encoding / decoding units, and 4 is a conversion unit. Encoding / decoding units 1, 2, 3
Is for encoding or decoding one component of the image data, and the conversion unit 4 is for performing mutual conversion between the encoded data of each component and the interleave format while decoding. The image data Li ^* , ai ^* , and bi ^* (i is a block number) input to the encoding / decoding units 1, 2, and 3 are color-converted from the RGB input image data, and the luminance is Li ^* and the color difference is It is assumed that ai ^* and bi ^* are input for each block (for example, 8 × 8 pixels).

First, the processing of the image data Li ^* will be described. The image data L _{1 *} input to the encoding / decoding unit 1,
L _{2 *} , ... Are encoded by the encoding / decoding unit 1 and packed into bit data C _L1 , C _L2 ,.
.. becomes data of a bit string in which _L1 , C _L2 , ... _Are continuously arranged, and the break of the block cannot be identified from this bit string. Therefore, the conversion unit 2 detects the end of the block while decoding the bit string, and cuts out the bit string C _{L1 in} which L _{1 *} is encoded.

When C _L1 is cut out, similarly, a bit string C _{a1 in} which a ₁ ^* is encoded is cut out and connected to C _L1 . Then, similarly, the bit string C _b1 is connected, and this is sequentially repeated to connect the code data for each block,
Can be converted to interleaved format.

When decoding is performed, the data input to the conversion unit 2 includes bit strings C _L1 , C _a1 , C _b1 , C _L2 , C _a2 ,
It is given in an interleaved format of C _b2 , .... The conversion unit 2 detects a block break while decoding the bit string in the same manner as described above, and sequentially distributes to the three encoding / decoding units 1, 2, and 3. Each encoding / decoding unit 1, 2,
3 is capable of converting bit string data for each block into image data and decoding the interleave format data into image data Li ^* , ai ^* , and bi ^* .

FIG. 2 is a block diagram showing a second example of the embodiment of the present invention. In the figure, the same parts as those in FIG. Reference numeral 5 denotes an encoding / decoding unit, which encodes / decodes two-component data.

In this embodiment, the output from the encoding / decoding unit 5 is the color difference signals ai ^* and bi ^* of the image data ^.
A ₁ ^* , a _{2 *} , ... And b _{1 *} , b _{2 *} , ... Encoded data C _a1 , C _a2 , ... And C _b1 , C _b2 , ...
Bit strings C _a1 , C _b1 , C _a2 , C _b2 , ... Converting each of the above into an interleaved format, but by giving information to the conversion unit 2 in advance, the conversion unit 2 can perform encoding / decoding. Connected bit string C from part 5
Code data of individual blocks can be cut out from _a1 , _Cb1 , _Ca2 , _Cb2 , ..., And decoding is performed together with the code data C _L1 , C _L2 , ... From the encoding / decoding unit 1. It is possible to obtain the data of the bit string converted into the interleaved format by cutting out each block while performing the operation. With such a configuration, the number of encoding / decoding units can be reduced by time-divisionally using the encoding / decoding unit 3 for the color difference signals a ^* and b ^{* in} the image data.

As described above, the present invention provides an apparatus for encoding or decoding a variable length code composed of a plurality of components,
By using a plurality of encoding / decoding units and a conversion unit that mutually converts by decoding the coded data of each component and the interleaved format, the data that has been compressed and coded at the same time during the coding operation is converted by the conversion unit. Since the data is rearranged and output in the interleaved format, the coding / decoding unit can operate without waiting for the coding results of other components and the packing operation, and thus can perform coding at high speed. Further, in the decoding operation, since the code for each component converted from the interleaved format is separated and input, the decoding operation can be performed at the same time, which enables a high-speed operation.

FIG. 3 is a block diagram of a first embodiment of the conversion unit 2 shown in FIG. In the figure, 11 is a control unit,
Reference numeral 12 is a block end detection unit, and 13 is a selection unit.
The encoding method is such that an image as shown in FIG. 9A has 8 × 8 pixels as one block, DCT operation is performed, each frequency component is quantized and Huffman encoding is performed, and L ^* , a
Output in interleaved format in the order of ^* and b ^* . This will be described with reference to FIG. Note that the reverse operation is performed in decoding.

FIG. 8 is an explanatory diagram of an example of Huffman code data. It is an example of data of one block of image data Li ^* , ai ^* , and bi ^* . FIG. 7 shows the data of each block as serial data. In FIG. 7, the portion underlined with a single line is Huffman code data, and the portion underlined with a double line is additional bit data. As can be seen from the comparison with FIG. 8, additional bit data is added after the Huffman code data to form a code string. In the description of FIG. 3, it is assumed that the code string shown in FIG. 7 is transferred from the encoding / decoding unit.

First, in the case of encoding, when the encoded data can be transferred from the encoding / decoding unit, the encoding / decoding unit 1
Issues the L ^* code REQ signal. Control unit 11 by this signal, relative to L ^* coding decoding unit 1, together with the issue L ^* code EN signal, to select section 13, and outputs a select signal to receive block termination detecting portions 12. When the block end detection unit 12 can decode the received code data string, the code data “01
0 ", run length 0, and additional bit length 1 can be obtained.

Next, when the data of the additional bit length is received from the L ^* encoding / decoding unit 1 and transferred as it is to the outside,
The next data received will be the first bit of the Huffman code. When this operation is repeated and the sum of the number of times the run length and the additional bit are transferred becomes 64, or
When (End Of Block) is detected, one block is formed. Next, when a code string is received from the a ^* encoding / decoding unit 2 and one block can be similarly formed, this time, the code string is received from the b _* encoding / decoding unit 3 and one block is similarly formed. Form. Thus, 1
An interleaved format is formed by connecting code data block by block.

In the case of decoding, the data transferred from the outside is input to the block end detection unit 12 and also transferred to the L ^* encoding / decoding unit 1. When one block is formed in the same way as the encoding, the encoding / decoding unit 2 of a ^* , b
Each E so that it is transferred in order of the encoding / decoding unit 3 of ^*.
It is sufficient to control the N signal and the select signal.

FIG. 4 is a block diagram of a second embodiment of the conversion unit 2 shown in FIG. In the figure, 21 is a control unit,
22 is a block end detecting unit, 23 is a selecting unit, 24 is a packing unit, 25 is an unpacking unit, 26 is a selecting unit, 2
Reference numerals 7 and 28 are registers. The coding method is the same as that described in the first embodiment, and interleave output is performed in the order of L ^* , a ^* , and b ^* . Further, it is assumed that the encoding / decoding units 1, 2, 3 output as 8-bit parallel data. Also in this description, the code string shown in FIG. 7 will be described as an example with reference to FIG.

In the case of encoding, when the encoded data can be transferred from the encoding / decoding unit, the encoding / decoding unit 1 outputs L ^*.
Issue the code REQ signal. With this signal, the control unit 21 outputs a select signal to the select unit 23 to select the code data from the L ^* encoding / decoding unit 1. The code data of L ^* sent is 8 bits of "01
001101 ”, and the selection unit 26 to the unpacking unit 2
After passing 5 as it is, it is input to the block end detection unit 22 and the packing unit 24 and stored in the register 27.
The code data sent to the packing unit 24 is stored in the register 2
8 is stored. The block end detection unit 22 performs Huffman decoding, but the decoded data is "0100".
Therefore, the break signal "4" is output. This "4"
Is a value obtained by adding both code lengths of the code length 3 and the additional bit length 1. This break signal is stored in the register 28.

The unpacking section 25 reads out from the register 27 by the break signal, finds the next Huffman code, and starts the next Huffman code, and the code string from the fifth bit and the next code transferred from the encoding / decoding section 1. 1-byte code data “1
The code data of a total of 8 bits up to the 4th bit of "0111111" is input to the block end detection unit 22, sent to the packing unit 24, and stored in the register 28. This 1-byte code data is “110110
11 ". The block end detector 22 decodes this code data. This coded data can be decoded up to the 7th bit, and the delimiter signal becomes "7", which is sent to the packing unit 24 and stored in the register 28. The packing unit 24 packs 1 byte of valid data from the delimiter signals “4” and “7” stored in the register 28 and outputs it to the outside.

The next 1-byte data is "1111101".
1 ". Since the code is not fixed even if this 1-byte data is decoded, the delimiter signal is set to "8" and the next 1-byte data is similarly sent. The sign is determined by the first bit, and the break signal is output as "1". The EOB is detected by the next 1-byte data. The EOB is 4 bits of the coded data that has been cued, and the remaining 4 bits and the delimiter signal “4” are recorded in the register 27 of the unpacking unit 25. Used to connect the next L ^* data. When the block end of L ^* is detected, the same operation is performed in the order of a ^* and b ^* to obtain an interleaved format.

In the case of decoding, the code data inputted from the outside is sent from the selection circuit 26 to the unpacking section 25 for cueing, and is effective while Huffman decoding is performed by the block end detecting section 22 as described above. When the data has 1 byte, it is packed by the packing unit 24 and sent to the encoding / decoding unit 1. When the end of the block of L ^* code data is detected, the subsequent code data is searched for, and similarly, the code data of a ^* and b ^* are encoded / decoded by the encoding / decoding units 2 and 3.
Output to

Thus, the first and second embodiments are
A select unit that selects the input / output destination of the code data of each component, a block end detecting unit that decodes the received Huffman code data and detects the block end, and a select unit when the block end detecting unit detects the block end. It is composed of a control unit that switches the units. This allows
When receiving the coded data of each component according to the order of the interleaved format, the received coded data of the component is Huffman-decoded to detect the fixed length data, the data is sent to the corresponding circuit, and the block end of the component can be detected. The decoding operation can be performed in parallel by switching the code data destination of the transmission destination. On the other hand, the data sent in parallel for each component is Huffman-decoded to detect fixed-length data, and when the block end of the component is detected, the code data from the next component is received and connected. By doing so, an interleave format code can be created.

FIG. 5 is a block diagram of a third embodiment of the conversion unit 2 shown in FIG. Reference numeral 31 is a control unit, 32 is a block end detection unit, 33 is a selection unit, 34 is a marker detection unit, and 35 is a marker processing unit. The first encoding method
Although it is the same as that described in the above embodiment, a marker can be further added to the code data, and therefore the same as the JPEG baseline method. Further, it is assumed that L ^* , a ^* , and b ^* are interleaved in order. In this embodiment, code data is serially sent from the encoding / decoding unit as in the first embodiment, but code data is transferred in 8-bit parallel as in the second embodiment. You may do it. The difference from the first embodiment described in FIG. 3 is that a marker detection unit 34 and a marker processing unit 35 are added.

FIG. 6 shows an example of a coding method using a marker used in the third embodiment, in which an RST marker is inserted.
FIG. 6 (A) is an interleave format, and FIG. 6 (B).
Is a non-interleaved format, CLn ^* block, which Ln ^* block of image data is encoded, likewise, Can ^* block, Cbn ^* block, Can ^* block of image data, Cbn ^* block The encoded one is shown.

At the time of encoding, the non-interleaved format encoded by the encoding / combining section is converted into the interleaved format by the converting section. First, the CLn ^* block shown in FIG. 6B is transferred from the selection unit 33 to the block end detection unit 32, the marker detection unit 34, and the marker processing unit 35. When the marker detection unit 34 detects the RST marker, the marker processing unit 35 adjusts the required bit number "1" for byte alignment and outputs the adjusted signal to the outside. Then, the RST marker of the Can ^* block and the Cbn ^* block sequentially transferred from the select unit and the bit “1” added for byte alignment are deleted,
As shown in (A), the interleave format is obtained by sequentially outputting to the outside.

In the decoding, the data in the interleaved format shown in FIG.
2, input to the marker detection unit 34 and the marker processing unit 35. When the marker detection unit 34 detects the RST marker before converting the CLn ^* block into the non-interleaved format, the marker processing unit 35 adjusts and adds the bit “1” for byte alignment, and the encoding / decoding unit. Transfer to 1. Regarding the Can ^* block and the Cbn ^* block, before transferring to the encoding / decoding units 2 and 3,
Bit "1" and R for byte alignment respectively
Add an ST marker. Further, the marker processing unit 35
It is also possible to perform byte stuffing that occurs during interleaved format conversion.

In this embodiment, a selector for selecting the input / output destination of the code data of each component, a block end detector for decoding the received Huffman code data to detect the block end, and a marker for the code data are detected. And a marker processing unit that adds or deletes a marker to the code data in accordance with the marker detection, and a control unit that switches the selection unit when the block end detection unit detects the block end. This allows
When receiving the coded data of each component according to the order of the interleave format, Huffman decoding the coded data of the received component to detect the fixed length data, send the data to the corresponding circuit, and further, when detecting the marker, While transmitting the marker as the code data, the block end of the component is detected, the destination of the code data of the component is switched, and then the detected marker is added to the beginning of the next component code data to be transmitted. Conversely, if the data sent in parallel for each component is Huffman-decoded to detect fixed-length data, and if a marker is detected,
If the marker block can detect the block end of the component while sending the code data, if the same marker that was detected previously is sent after switching the code data destination of the destination, delete the marker and delete the code data. Can be converted to interleaved format by connecting.

[0032]

As is apparent from the above description, according to the present invention, since the encoding processing and the decoding processing can be performed in parallel for each component, it is possible to operate at high speed. Further, even in a lossy encoding method such as JPEG, since only the Huffman code is decoded and converted into the interleaved format, there is an effect that deterioration in image quality due to rearrangement does not occur.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment of an image encoding / decoding device of the present invention.

FIG. 2 is a block diagram showing a second embodiment of an image encoding / decoding device of the present invention.

[Fig. 3] Fig. 3 is a block diagram illustrating a first example of a conversion unit in the first embodiment of the image encoding / decoding device of the present invention.

FIG. 4 is a block diagram showing a second example of the conversion unit in the first embodiment of the image encoding / decoding apparatus of the present invention.

FIG. 5 is a block diagram showing a third working example of the conversion unit in the first embodiment of the image coding / decoding apparatus of the present invention.

FIG. 6 is an explanatory diagram of an interleaved format and a non-interleaved format.

FIG. 7 is an explanatory diagram of an example of a code string.

FIG. 8 is an explanatory diagram of an example of Huffman code data.

FIG. 9 is a block diagram of a general encoding method.

[Explanation of symbols]

1, 2, 3, 5 ... Encoding / decoding section, 4 ...
1, 31 ... Control unit, 12, 22, 32 ... Block end detection unit, 13, 23, 33 ... Select unit, 24 ...
Packing unit, 25 ... Unpacking unit, 26 ... Selection unit, 27, 28 ... Register, 34 ... Marker detection unit, 35
... Marker processing unit.

Claims (3)

[Claims] 1. An image coding / decoding device for coding an image composed of a plurality of components into a variable-length code for each block or for decoding an image from the variable-length code into a plurality of coding / decoding. And a conversion means for mutually converting the code of each component and the interleave format, wherein the conversion means performs conversion to the conversion destination code based on the information obtained by decoding the conversion source code. Image encoding / decoding device. 2. The converting means includes a selecting means for selecting the encoding / decoding means as an input / output destination of the code of each component, a block end detecting means for decoding the received code and detecting a block end. The image coding / decoding apparatus according to claim 1, further comprising a control unit that switches the selecting unit according to a block end detected by the block end detecting unit. 3. The encoding / decoding means processes a code including a marker, and the conversion means selects a selection means for selecting the encoding / decoding means as an input / output destination of the code of each component. Block end detecting means for decoding the received code and detecting the block end, marker detecting means for detecting a marker from the received code, and adding a marker to the code when the marker is detected by the marker detecting means 7. A marker processing means for outputting to the selecting means or deleting a marker from a code and outputting the marker to the outside, and a control means for switching the selecting means according to the block end detected by the block end detecting means. 1. The image encoding / decoding device according to 1.