Data encoding device and data decoding device

• US 6,717,534 B2
• Filed: 01/15/2003
• Issued: 04/06/2004
• Est. Priority Date: 01/18/2002
• Status: Expired due to Fees

• Current Assignee: Fuji Xerox Company Limited (Xerox Holdings Corp.)
• Original Assignee: Fuji Xerox Company Limited (Xerox Holdings Corp.)
• Inventors: Yokose, Taro
• Primary Examiner(s): JeanGlaude, Jean
• Application Number:
  US10/342,204
• Publication Number:
  US 20030137438A1
• Time in Patent Office: 447 Days
• Field of Search: 341/50, 341/67, 341/65, 341/63, 714/701, 704/223
• US Class Current: 341/65
• CPC Class Codes: H03M 7/40 Conversion to or from variable length codes, e.g. Shannon-Fano code, Huffman code, Morse code
• CPC Class Codes: H03M 7/48 alternating with other codes during the code conversion process, e.g. run-length coding being performed only as long as sufficientlylong runs of digits of the same kind are present

Abstract

A data encoding device and a data decoding device. A data encoding device refers to first and second encoding tables to search for a code word correlated with encoding data. One of the code words is selected according to predetermined criteria. When the selected code word requires additional information, additional information is generated. A data decoding device refers to the first and second encoding tables and retrieves a data element from at least one of the tables. When additional information is available, original data is calculated based on the data element and the additional information. When additional information is not available, the retrieved data element is output without modification as original data.

Claims

1. A data encoding device, comprising:

an encoding table for correlating a data element with a code word such that one data element is correlated with N number of code words and one code word is correlated with one data element, the data element serving as a unit of data encoding, N being an integer larger than zero;

a retrieve unit for determining a data element corresponding to each of a series of encoding data and for retrieving the N number of code words correlated with the determined data element with reference to the encoding table;

a selector for selecting one code word from among the N number of code words according to predetermined criteria; and

a generator means for generating, as required, additional information which specifies encoding data correlated with the selected code word among one or more encoding data corresponding to the determined data element correlated with the selected code word,

whereby

each encoding data is converted into either additional information attached encoded data or normal encoded data, the additional information attached encoded data consisting of a code word and additional information, the normal encoded data consisting of a code word.

2. The data encoding device according to claim 1, wherein the selector selects the shortest code word from among the N number of code words as defined as the predetermined criteria.

3. The data encoding device according to claim 1, wherein the selector selects one code word according to a predetermined priority order as defined as the predetermined criteria.

4. A data encoding device, comprising:

encoding tables each for correlating one data element with one code word, the data element serving as a unit of data encoding;

a retrieve unit for determining a data element corresponding to each of a series of encoding data and for retrieving N number of encoding tables which each define a code word correlated with the determined data element, N being an integer larger than zero;

a selector for selecting one encoding table from among the N number of encoding tables according to a predetermined criteria to output a code word which is defined by the selected encoding table as correlated with the determined data element;

a generator for generating, as required, additional information which specifies encoding data correlated with the selected code word among one or more encoding data corresponding to the determined data element correlated with the selected code word,

whereby

each encoding data is converted into either additional information attached encoded data or normal encoded data, the additional information attached encoded data consisting of a code word and additional information, the normal encoded data consisting of a code word.

5. The data encoding device according to claim 4, wherein the selector selects an encoding table which correlates the data element with the shortest code word from among the N number of encoding tables as defined as the predetermined criteria.

6. The data encoding device according to claim 4, wherein the selector selects one encoding table according to a predetermined priority order as defined as the predetermined criteria.

7. The data encoding device according to claim 4, wherein the selector outputs selection information specifying the selected encoding table for correlation with each code word.

8. A data decoding device, comprising:

an encoding table for correlating a data element with a code word such that one data element is correlated with N number of code words and one code word is correlated with one data element, the data element serving as a unit of data encoding, N being an integer larger than zero;

a retrieve unit for sequentially extracting encoded data from a series of encoded data obtained by a data encoding device and for retrieving a data element correlated with a code word contained in the extracted encoded data with reference to the encoding table; and

a decoder for decoding, when the extracted encoded data is additional information attached encoded data, additional information based on the retrieved data element and the extracted additional information.

9. A data decoding device, comprising:

encoding tables each for correlating one data element with a code word, the data element serving as a unit of data encoding;

a retrieve unit for sequentially extracting encoded data from a series of encoded data obtained by a data encoding device and for retrieving a data element correlated with a code word contained in the extracted encoded data with reference to one of the encoding tables; and

a decoder for decoding, when the extracted encoded data is additional information attached encoded data, additional information based on the retrieved data element and the extracted additional information.

10. A data decoding device, comprising:

encoding tables each for correlating one data element with a code word, the data element serving as a unit of data encoding;

a retrieve unit for sequentially extracting encoded data from a series of encoded data obtained by a data encoding device to extract a code word contained in the extracted encoded data, for selecting one encoding table from among the encoding tables based on selection information which is correlated with the extracted code word, and for retrieving a data element correlated with the extracted code word with reference to the selected encoding table; and

a decoder for decoding, when the extracted encoded data is additional information attached encoded data, additional information based on the determined data element and the extracted additional information.

11. A data encoding method employing an encoding table which correlates a data element with a code word such that one data element is correlated with N number of code words and one code word is correlated with one data element, the data element serving as a unit of data encoding, N being an integer larger than zero;

the method, comprising;

a search step of determining a data element corresponding to each of a series of encoding data to determine the N number of code words correlated with the determined data element with reference to the encoding table;

a selection step of selecting one code word from among the N number of code words according to a predetermined criteria; and

a generation step of generating, as required, additional information which specifies encoding data correlated with the selected code word among one or more encoding data corresponding to the determined data element correlated with the selected code word,

whereby

each encoding data is converted into either additional information attached encoded data or normal encoded data, the additional information attached encoded data consisting of a code word and additional information, the normal encoded data consisting of a code word.

12. A data decoding method employing a table which correlates a data element with a code word such that one data element is correlated with N number of code words and one code word is correlated with one data element, the data element serving as a unit of data encoding, N being an integer larger than zero, the method, comprising:

a search step of sequentially extracting encoded data from a series of encoded data obtained by a data encoding device and determining a data element correlated with a code word contained in the extracted encoded data with reference to the table; and

a decoding step of decoding, when the extracted encoded data is additional information attached encoded data, additional information based on the determined data element and the extracted additional information.

13. Encoded data, generated using an encoding table which correlates a data element with a code word such that one data element is correlated with N number of code words and one code word is correlated with one data element, the data element serving as a unit of data encoding, N being an integer larger than zero, as the product of:

a search step of determining a data element corresponding to each of a series of encoding data and for determining the N number of code words correlated with the determined data element with reference to the encoding table;

a selection step of selecting one code word from among the N number of code words according to a predetermined criteria; and

a generation step of generating, as required, additional information which specifies encoding data correlated with the selected code word among one or more encoding data corresponding to the determined data element correlated with the selected code word,

to thereby convert each encoding data into either additional information attached encoded data or normal encoded data, the additional information attached encoded data consisting of a code word and additional information, the normal encoded data consisting of a code word,

wherein

the encoded data contains at least one of the additional information attached encoded data and the normal encoded data based on the series of encoding data.

14. Encoded data generated by encoding a series of encoding data, including additional information attached encoded data and normal encoded data, the additional information attached encoded data consisting of a code word and additional information and the word data consisting of a code word.

15. Encoded data, generated using two or more encoding tables which respectively correlate one data element with different code words, the data element serving as a unit of data encoding, as the product of:

a search step of determining a data element corresponding to each of a series of encoding data and determining N number of encoding tables which each define a code word correlated with the determined data element, N being an integer larger than zero;

a selection step of selecting one encoding table from among the N number of encoding tables according to predetermined criteria to output a code word correlated with the determined data element according to the selected encoding table;

a generation step of generating, as required, additional information which specifies encoding data correlated with the selected code word among one or more encoding data corresponding to the determined data element correlated with the selected code word,

to thereby convert each encoding data into either additional information attached encoded data or normal encoded data, the additional information attached encoded data consisting of a code word and additional information, the normal encoded data consisting of a code word,

wherein

the encoded data contains at least one additional information attached encoded data and one normal encoded data according to the series of encoding data.

16. Encoded data according to claim 15, further containing information specifying an encoding table which is selected when outputting each code word.

17. A storage medium storing a data encoding program which employs an encoding table which correlates a data element with a code word such that one data element is correlated with N number of code words and one code word is correlated with one data element, the data element serving as a unit of data encoding, N being an integer larger than zero, and which, when executed, causes a computer to execute:

a search step of determining a data element corresponding to each of a series of encoding data and determining the N number of code words correlated with the determined data element with reference to the encoding table;

a selection step of selecting one code word from among the N number of code words according to a predetermined criteria; and

a generation step of generating, as required, additional information which specifies encoding data correlated with the selected code word among one or more encoding data corresponding to the determined data element correlated with the selected code word,

to thereby convert encoding data into either additional information attached encoded data or normal encoded data, the additional information attached encoded data consisting of a code word and additional information, the normal encoded data consisting of a code word.

18. A storage medium storing a data decoding program which employs an encoding table which correlates a data element with a code word such that one data element is correlated with N number of code words and one code word is correlated with one data element, the data element serving as a unit of data encoding, N being an integer larger than zero, and which, when executed, causes a computer to execute:

a search step of sequentially extracting encoded data from a series of encoded data obtained through encoding according to a data encoding program and determining a data element correlated with a code word contained in the extracted encoded data with reference to the encoding table, the data encoding program employing an encoding table which correlates a data element with a code word such that one data element is correlated with N number of code words and one code word is correlated with one data element, the data element serving as a unit of data encoding, N being an integer larger than zero, and causing a computer to execute a search step of determining a data element corresponding to each of a series of encoding data to determine the N number of code words correlated with the determined data element with reference to the encoding table;

a selection step of selecting one code word from among the N number of code words according to a predetermined criteria; and

a generation step of generating, as required, additional information which specifies encoding data correlated with the selected code word among one or more encoding data corresponding to the determined data element correlated with the selected code word,

to thereby convert encoding data into either additional information attached encoded data or normal encoded data, the additional information attached encoded data consisting of a code word and additional information, the normal encoded data consisting of a code word;

and

a decoding step of extracting, when the extracted encoded data is additional information attached encoded data, additional information from the extracted encoded data to restore data before encoding based on the determined data element and the extracted additional information.