Code converter, encoder, image output device and method thereof

• US 20030044079A1
• Filed: 03/14/2002
• Published: 03/06/2003
• Est. Priority Date: 09/06/2001
• Status: Active Grant

• Current Assignee: Fuji Xerox Company Limited (Xerox Holdings Corp.)
• Original Assignee: Fuji Xerox Company Limited (Xerox Holdings Corp.)
• Inventors: Yokose, Taro
• Granted Patent: US 7,039,249 B2
• Time in Patent Office: Days
• US Class Current: 382/246
• CPC Class Codes: G06T 9/00 Image coding bandwidth or redundancy reduction for static pictures H04N1/41; coding or decoding of static colour picture signals H04N1/64; methods or arrangements for coding, decoding, compressing or decompressing digital video signals H04N19/00

Abstract

Conversion between different codes can be implemented at high speed by a small device. A code input unit inputs a code. A compatible information reference unit refers to compatible information of each compressed symbol before and after code conversion, which then sends out compatible information data to a compressed symbol conversion unit. The compressed symbol conversion unit converts each of the compressed symbols in the input code data to a form adapted to a code to be converted based on the compatible information data, which then sends out converted code data to a converted code output unit.

Claims

1. A code converter comprising:

a code input part which inputs a code;

a compatible information reference part which refers to compatible information;

a conversion part which converts the input code based on the compatible information; and

a code output part which outputs a converting result of the conversion part,

wherein, to ensure compatibility between at least two codes, a correspondence between compressed symbols before and after conversion is described into the compatible information, whereby the conversion part converts the symbols while keeping them compressed.

2. The code converter according to claim 1, wherein the conversion part comprises a codeword cutting part which cuts out a codeword from the input code, a codeword substitution part which substitutes the cut-out codeword, and a codeword coupling part which couples the codeword substituted by the codeword substitution part to generate a code.

9. The code converter according to claim 1, wherein the compatible information reference part comprises one of a look-up table and a multistage look-up table through virtual representation.

10. The code converter according to claim 1, wherein the compatible information reference part uses a predetermined relational expression to calculate a relation between the symbols by computation.

11. The code converter according to claim 1, wherein one of objects of code conversion is quantizing coefficient conversion, and the compatible information shows a relation between quantizing results by different quantizing coefficients.

12. The code converter according to claim 1, wherein one of objects of code conversion is codeword conversion, and the compatible information shows a relation between codewords in different codes.

13. The code converter according to claim 12, wherein the codeword is a Huffman code.

14. The code converter according to claim 1, wherein one of objects of code conversion is maximum run length conversion, and the compatible information shows a relation between run values in different maximum run lengths.

15. The code converter according to claim 1, wherein code conversion has plural objects, and the compatible information comprises parallelized or logically combined plural pieces of compatible information.

16. The code converter according to claim 1, wherein when symbols described into the compatible information are not independent on the code, the conversion part comprises a symbol cutting part which cuts out the described symbols.

17. The code converter according to claim 1, wherein even additional information is useful only for specific encoding, the additional information is described into the compatible information and included in a code.

18. The code converter according to claim 1, wherein additional information which is useful only for specific encoding is not described into the compatible information when it is known that no later code conversion is performed, and the additional information is removed from a code.

19. The code converter according to claim 1, wherein the compatible information reference part can change the compatible information to be described to control setting of the compatible information reference part according to a peripheral condition.

3. An encoder comprising:

a data input part which inputs data;

a compatible information reference part which refers to compatible information;

an encoding part which encodes the input data by a predetermined method based on the compatible information; and

a code output part which outputs an encoding result of the encoding part,

wherein a component of a compressed symbol to be encoded necessary to ensure compatibility between at least two codes is described into the compatible information, whereby the encoding part performs encoding which facilitates conversion.

4. The encoder according to claim 3, wherein the encoding part comprises a symbol generation part which generates a symbol from the input data, a codeword substitution part which substitutes a codeword for the generated symbol, and a codeword coupling part which couples the codeword to generate a code.

5. An image output device comprising:

an image input part which inputs an image;

a compatible information reference part which refers to compatible information;

an encoding part which encodes the input image to generate a code based on the compatible information;

at least one conversion part which converts the code based on the compatible information to generate a converted code;

a code decoding part which decodes the code;

at least one converted code decoding part which decodes the converted code;

an image output part which outputs a decoding result of the code decoding part; and

at least one image output parts which outputs a decoding result of the corresponding at least one converted code decoding part,

wherein a component of a compressed symbol to be encoded necessary to ensure compatibility between at least two codes is described into the compatible information, whereby the encoding part performs encoding which facilitates conversion, and a correspondence between compressed symbols before and after conversion is described into the compatible information, whereby the conversion part converts the symbols while keeping them compressed.

7. The image output device according to claim 5, wherein the code is converted by the conversion part before or after a code managing process such as storage or transmission.

8. The image output device according to claim 5, wherein the compatible information reference part comprises a compatible information reference part for the encoding part and a compatible information reference part for the conversion part which are prepared independently, thereby storing only necessary information.

6. An image output device comprising:

an image input part which inputs an image;

a compatible information reference part which refers to compatible information;

an encoding part which encodes the input image based on the compatible information;

at least one conversion part which converts the code based on the compatible information to generate a converted code;

at least one converted code decoding part which decodes the converted code; and

at least one image output part which outputs a decoding result of the corresponding at least one converted code decoding part,

wherein a component of a compressed symbol to be encoded necessary to ensure compatibility between at least two codes is described into the compatible information, whereby the encoding part performs encoding which facilitates conversion, and a correspondence between compressed symbols before and after conversion is described into the compatible information, whereby the conversion part converts the symbols while keeping them compressed.

20. A code converting method comprising the steps of:

inputting a code;

referring to compatible information showing a correspondence between codes to convert a code while keeping it compressed; and

outputting a converting result.

21. An encoding method comprising the steps of:

inputting data;

referring to compatible information including a component of a compressed symbol to be encoded necessary to ensure compatibility between at least two codes to encode the data; and

outputting an encoding result.

22. A code converting method comprising:

inputting a code;

referring to compatible information;

converting the input code based on the compatible information; and

outputting a converting result of the conversion step,

wherein to ensure compatibility between at least two codes, a correspondence between compressed symbols before and after conversion is described into the compatible information, whereby the symbols are converted while being kept compressed.

23. An encoding method comprising:

inputting data;

referring to compatible information;

encoding the input data by a predetermined method based on the compatible information; and

outputting an encoding result of the encoding step,

wherein a component of a compressed symbol to be encoded necessary to ensure compatibility between at least two codes is described into the compatible information, whereby the encoding step performs encoding which facilitates conversion.

24. An image output method comprising:

inputting an image;

referring to compatible information;

encoding the input image based on the compatible information;

converting the code based on the compatible information to generate a converted code;

decoding the code;

decoding the converted code;

outputting a decoding result of the code decoding step; and

outputting a decoding result of the converted code decoding step,

wherein a component of a compressed symbol to be encoded necessary to ensure compatibility between at least two codes is described into the compatible information, whereby the encoding part performs encoding which facilitates conversion, and a correspondence between compressed symbols before and after conversion is described into the compatible information, whereby the symbols are converted while being kept compressed.

25. A storage medium readable by a computer, the storage medium storing a program of instructions executable by the computer to perform a function for converting a code, the function comprising the steps of:

inputting a code;

referring to compatible information;

converting the input code based on the compatible information; and

outputting a converting result of the conversion step,

wherein to ensure compatibility between at least two codes, a correspondence between compressed symbols before and after conversion is described into the compatible information, whereby the symbols are converted while being kept compressed.

26. A storage medium readable by a computer, the storage medium storing a program of instructions executable by the computer to perform a function for encoding which assumes later code conversion, the function comprising the steps of:

inputting data;

referring to compatible information;

encoding the input data by a predetermined method based on the compatible information; and

outputting an encoding result of the encoding step,

wherein a component of a compressed symbol to be encoded necessary to ensure compatibility between at least two codes is described into the compatible information, whereby encoding which facilitates conversion is performed in the encoding step.

27. A storage medium readable by a computer, the storage medium storing a program of instructions executable by the computer to perform a function for converting a code to generate a converted code, decoding the converted code, and outputting the decoding result, the function comprising the steps of:

inputting a code;

referring to compatible information;

converting the code based on the compatible information to generate a converted code;

decoding the converted code; and

outputting a decoding result of the converted code decoding step,

wherein a correspondence between compressed symbols before and after conversion is described into the compatible information, whereby the symbols are converted while being kept compressed.