Encoding device and method utilizing table data for selection of bit planes

• US 7,574,061 B2
• Filed: 09/23/2002
• Issued: 08/11/2009
• Est. Priority Date: 09/25/2001
• Status: Expired due to Fees

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: Sato, Yutaka
• Primary Examiner(s): Bella; Matthew C
• Assistant Examiner(s): Ge; Yuzhen
• Application Number:
  US10/252,335
• Publication Number:
  US 20030081847A1
• Time in Patent Office: 2,514 Days
• Field of Search: 382/240
• US Class Current: 382/239
• CPC Class Codes: H04N 19/12 Selection from among a plurality of transforms or standards, e.g. selection between discrete cosine transform [DCT] and sub-band transform or selection between H.263 and H.264
• CPC Class Codes: H04N 19/152 by measuring the fullness of the transmission buffer
• CPC Class Codes: H04N 19/156 Availability of hardware or computational resources, e.g. encoding based on power-saving criteria
• CPC Class Codes: H04N 19/1883 the unit relating to sub-band structure, e.g. hierarchical level, directional tree, e.g. low-high [LH], high-low [HL], high-high [HH]
• CPC Class Codes: H04N 19/63 using sub-band based transform, e.g. wavelets

Abstract

An encoding process is provided which can easily control the compression rate or guarantee a maximum required processing time when representing the factor data, obtained from a wavelet transformation, as codes corresponding to each of the bit planes. To this end, a plurality of sets of table data each specifying the bit planes to be discarded for each of the sub bands are provided, and by selecting one of these sets according to the various conditions set forth such as the desired compression rate or a maximum required processing time, the amount of data to be encoded can be optionally set and/or a maximum required processing time can be optionally set for an apparatus with a predetermined processing speed.

Claims

1. An encoding device that represents image data in the form of a plurality of bit planes for each of a plurality of sub bands and encodes said image data for each bit plane, comprising:

a plurality of tables with respective sets of table data, wherein each set of table data is associated with a corresponding compression rate and amount of data to be encoded and specifies a corresponding subset of either the bit plane(s) to be discarded or the bit plane(s) to be encoded for each sub band; and

an encoding part configured to encode a predetermined amount of data in an amount X of time and select a set of table data, corresponding to one of said plurality of tables, based on a maximum required processing time Y,

wherein said maximum required processing time is an amount of time within which processing by said encoding device of said image data is required to be completed,

wherein said encoding part selects the set of table data corresponding to the table that is associated with the largest amount of data to be encoded amongst tables associated with amounts of data to be encoded that do not exceed a ratio Y/X.

2. The encoding device as claimed in claim 1, wherein in said sets of table data, the number of bit planes to be discarded increase as the frequency of the corresponding sub band increases.

3. The encoding device as claimed in claim 1, wherein an entropy process is performed on the bit plane(s) specified by the selected set of table data.

4. The encoding device as claimed in claim 1, wherein a number of coding passes is determined from the selected set of table data.

5. The encoding device as claimed in claim 1, wherein said image data comprise coefficient data obtained from a two dimensional discrete wavelet transformation.

6. The encoding device as claimed in claim 1, wherein the selected set of table data specifies the bit plane(s) to be discarded for each sub band.

7. The encoding device as claimed in claim 1, wherein the selected set of table data specifies the bit plane(s) to be encoded for each sub band.

8. The encoding device as claimed in claim 1, wherein said plurality of tables are associated with respective code quantities.

9. The encoding device as claimed in claim 1, wherein said plurality of tables are associated with respective amounts of data to be encoded.

10. The encoding device as claimed in claim 1, wherein said plurality of tables are associated with respective required processing times.

11. An encoding method, performed by an encoding device, for representing image data in the form of a plurality of bit planes for each of a plurality of sub bands and encoding said image data for each bit plane comprising:

storing a plurality of tables with respective sets of table data, wherein each set of table data is associated with a corresponding compression rate and amount of data to be encoded and specifies a corresponding subset of the bit plane(s) to be discarded or the bit plane(s) to be encoded for each sub band;

selecting by an encoding device configured to encode a predetermined amount of data in an amount X of time, and based on a maximum required processing time Y, a set of table data corresponding to one of said plurality of tables,

wherein said encoding device selects the set of table data corresponding to the table that is associated with the largest amount of data to be encoded amongst tables associated with amounts of data to be encoded that do not exceed a ratio Y/X; and

using the selected set of table data to determine either the bit plane(s) to be discarded or the bit plane(s) to be encoded for each sub band,

wherein said maximum required processing time is an amount of time within which processing by said encoding method is required to be completed.

12. The encoding method as claimed in claim 11, wherein in said sets of table data, the number of bit planes to be discarded increase as the frequency of the corresponding sub band increases.

13. The encoding method as claimed in claim 11, further comprising determining a number of coding passes based on the selected set of table data.

14. The encoding method as claimed in claim 11, wherein said image data comprise coefficient data obtained from a two dimensional discrete wavelet transformation.

15. The encoding method as claimed in claim 11, wherein the selected set of table data is utilized to determine the bit plane(s) to be discarded for each sub band.

16. The encoding method as claimed in claim 11, wherein the selected set of table data is utilized to determine the bit plane(s) to be encoded for each sub band.

17. A computer readable medium tangibly embodying a program of instructions executable by a computer to perform a process for representing image data in the form of a plurality of bit planes for each of a plurality of sub bands and encoding said image data for each bit plane, said process comprising:

storing a plurality of tables with respective sets of table data, wherein each set of table data is associated with a corresponding compression rate and specifies a corresponding subset of the bit plane(s) to be discarded or the bit plane(s) to be encoded for each sub band;

selecting by an encoding device configured to encode a predetermined amount of data in an amount X of time, and based on a maximum required processing time Y, a set of table data corresponding to one of said plurality of tables,

wherein said encoding device selects the set of table data corresponding to the table that is associated with the largest amount of data to be encoded amongst tables associated with amounts of data to be encoded that do not exceed a ratio Y/X; and

using the selected set of table data to determine either the bit plane(s) to be discarded or the bit plane(s) to be encoded for each sub band,

wherein said maximum required processing time is an amount of time within which processing by said process is required to be completed.