Method and system for weighted encoding

• US 9,106,914 B2
• Filed: 05/25/2006
• Issued: 08/11/2015
• Est. Priority Date: 05/25/2006
• Status: Expired due to Fees

• Current Assignee: Interdigital Vc Holdings, Inc. (InterDigital, Inc.)
• Original Assignee: Thomson Licensing (Vantiva SA)
• Inventors: Doser, Ingo Tobias
• Primary Examiner(s): Truong, Thanhnga B
• Application Number:
  US12/226,856
• Publication Number:
  US 20090067506A1
• Time in Patent Office: 3,365 Days
• Field of Search: 375/240.18, 375/E7.134, 375/E7.145, 375/240.24, 382/232, 382/239, 358/1.1, 358/1.8, 348/229.1, 345/690, 341/61
• US Class Current: 1/1
• CPC Class Codes: H04N 19/115 Selection of the code volume for a coding unit prior to coding
• CPC Class Codes: H04N 19/124 Quantisation
• CPC Class Codes: H04N 19/126 Details of normalisation or weighting functions, e.g. normalisation matrices or variable uniform quantisers
• CPC Class Codes: H04N 19/154 Measured or subjectively estimated visual quality after decoding, e.g. measurement of distortion use of rate-distortion criteria H04N19/147
• CPC Class Codes: H04N 19/17 the unit being an image region, e.g. an object
• CPC Class Codes: H04N 19/176 the region being a block, e.g. a macroblock
• CPC Class Codes: H04N 19/60 using transform coding

Abstract

A method and system for weighted encoding of image data includes a transformation device configured to determine a non-linear transformation function for use in weighting an encoding of image data such that selected areas of the image data where increased detail is desired are encoded using a disproportionately greater number of bits of a total number of bits available for characterizing the image data. The system of the present invention can further include an encoding device configure to encode the weighted image data. In one embodiment of the present invention, the transformation device includes an analysis device configured to arrange pixel information into groups according to bit depths of the pixels of the image data, a post processing device configured to receive the organized pixel information and determine respective gains for the groups, and a transformation generation device configured to determine the transformation function based upon the respective gains.

Claims

1. A method for weighted encoding of image data, comprising:

applying, using a transforming device, a non-linear transformation function to said image data such that selected areas of said image data where increased precision is desired are encoded with an increased bit depth, wherein the step of applying the non-linear transformation function further comprising;

arranging pixel information into groups according to bit depths of the pixels of said image data;

determining respective gains for said groups, wherein said respective gains are dependent upon a respective number of pixels in said groups; and

determining said transformation function based upon said respective gains.

2. The method of claim 1, wherein said selected areas of said image data include areas where quantization artifacts are likely to occur.

3. The method of claim 1, further comprising:

applying a sliding window to said image data to determine a subset of said image data for creating said groups.

4. The method of claim 1, wherein said groups comprise bins of a histogram.

5. The method of claim 1, wherein said gains are used to weigh said selected areas of said image data to adjust the bit depths of the pixels of said image data.

6. The method of claim 1, wherein said transformation function is applied to said image data using a lookup table.

7. The method of claim 6, wherein said lookup table comprises a respective lookup table for different colors of the pixels of said image data.

8. The method of claim 1, further comprising determining an inverse transformation function for use in decoding said image data.

9. A system for weighted encoding of image data, comprising:

a transformation device configured to determine a non-linear transformation function to be applied to said image data such that selected areas of said image data where increased detail is desired can be encoded with an increased bit depth; and

an encoding device configured to encode said image data;

wherein said transformation device comprises;

an analysis device configured to arrange pixel information into groups according to bit depths of the pixels of said image data;

a post processing device configured to receive the organized pixel information and determine respective gains for said groups, wherein said respective gains are dependent upon a respective number of pixels in said groups; and

a transformation generation device configured to determine said transformation function based upon said respective gains, said transformation function transforming said image data to a second signal of lower bit depth based upon the corresponding gains.

10. The system of claim 9, wherein said analysis device arranges pixel information into bins of a histogram based upon respective pixel values of said pixels.

11. The system of claim 9, wherein said transformation device comprises a lookup table for applying the transformation function to said image data.

12. The system of claim 11, wherein the lookup table includes a respective lookup table for different colors of the pixels of said image data.

13. The system of claim 9, further comprising an inverse transformation device configured to apply an inverse transformation function to said image data.

14. The system of claim 13, wherein said inverse transformation device comprises a lookup table for applying the inverse transformation function to said encoded image data.

15. The system of claim 14, wherein the lookup table includes a respective lookup table for different colors of the pixels of said image data.

16. The system of claim 9, wherein said analysis device arranges the pixel information based upon a sliding window, the sliding window determining a subset of said image data for creating said groups.

17. The system of claim 9, wherein said transformation device applies said transformation function to said image data for weighting said image data to be encoded.

18. A method for weighted encoding of image data, comprising:

applying a transformation function to said image data such that selected areas of said image data where increased precision is desired are encoded with an increased bit depth;

wherein said applying is performed using a transformation device, and said transformation function is applied to said image data using a lookup table;

wherein the applying step further comprising;

arranging pixel information into groups according to bit depths of the pixels of said image data;

determining respective gains for said groups, wherein said respective gains are dependent upon a respective number of pixels in said groups; and

determining said transformation function based upon said respective gains.

19. The method of claim 18, wherein said selected areas of said image data include areas where quantization artifacts are likely to occur.

20. The method of claim 18, wherein said transformation function comprises a non-linear transformation function.