IPC분류정보
| 국가/구분 |
United States(US) Patent
등록
|
| 국제특허분류(IPC7판) |
|
| 출원번호 |
US-0986270
(2011-01-07)
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| 등록번호 |
US-8576907
(2013-11-05)
|
|
발명자
/ 주소 |
- Demos, Gary A.
- Ruhoff, David
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| 출원인 / 주소 |
- Dolby Laboratories Licensing Corporation
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| 대리인 / 주소 |
|
| 인용정보 |
피인용 횟수 :
3 인용 특허 :
72 |
초록
▼
Methods, systems, and computer programs for improved quality video compression. Image quality from MPEG-style video coding may be improved by preserving a higher number of bits during intermediate encoding and decoding processing steps. Problems of inverse discrete cosine transform (IDCT) mismatch c
Methods, systems, and computer programs for improved quality video compression. Image quality from MPEG-style video coding may be improved by preserving a higher number of bits during intermediate encoding and decoding processing steps. Problems of inverse discrete cosine transform (IDCT) mismatch can be eliminated by exactly matching the IDCT function numerical algorithm of the decoder to the IDCT function numerical algorithm used for the decoding portion of the encoder. Also included is an application of high precision compression to wide dynamic range images by extending the range of the “quantization parameter” or “QP”. The extension of QP may be accomplished either by increasing the range of QP directly, or indirectly through a non-linear transformation. Also included is an application of extended intermediate processing precision and an extended QP range to reduced contrast regions of an image to extend the precision with which the low-contrast portions are compression coded.
대표청구항
▼
1. A method for coding a picture of a wide dynamic range, the method being performed with a video coding system comprising at least an encoder, the method comprising: determining a set of representational quantization parameter (QP) codes for quantizing blocks of transformed pixel values in a pictur
1. A method for coding a picture of a wide dynamic range, the method being performed with a video coding system comprising at least an encoder, the method comprising: determining a set of representational quantization parameter (QP) codes for quantizing blocks of transformed pixel values in a picture, the set of representational quantization parameter codes having at least 32 values, wherein the set of representational quantization parameters codes is within a first set of levels;extending the first set of levels of said representational quantization parameter codes into a second set of levels using a non-linear mapping function, wherein the second set of levels is wider than the first set of levels, depends on an image bit depth, and corresponds to a set of determined quantization parameter (QPd) values, and wherein extending the first set of levels of the representation quantization parameter codes comprises a mapping of respective representational quantization parameter codes to corresponding determined quantization parameter values;for a block of transformed pixel values of the picture, selecting a representational quantization parameter code from the set of representational quantization parameter codes;for the block of transformed pixel values of the picture, using the mapping to select a determined quantization parameter value for the selected representational quantization parameter code; andquantizing the block of transformed pixel values, with the encoder, using the selected determined quantization parameter value. 2. The method of claim 1, wherein the picture is a wide dynamic range picture that has a bit depth greater than 8 bits. 3. The method of claim 2, wherein determining each quantization parameter value is based upon regional information with respect to the picture. 4. The method of claim 3, wherein the regional information includes local image region contrast within the picture. 5. The method of claim 3, wherein the regional information includes local dynamic range within the picture. 6. The method of claim 3, wherein the regional information includes local detail amplitudes within the picture. 7. The method of claim 3, wherein the regional information includes local motion between one or more sequential frames. 8. The method of claim 3, further comprising determining the regional information for a macroblock in the picture based on a brightness and a contrast within the respective macroblock. 9. The method of claim 2, wherein the video coding system further comprises a decoder, wherein the method further comprises: accessing the compressed picture by the decoder;selecting with the decoder, at least one representational quantization parameter code for a block of transformed pixel values of the received picture;for the block of transformed pixel values of the received picture, using the mapping to select the determined quantization parameter value corresponding to the selected representational quantization parameter code; anddequantizing, with the decoder, the block of transformed pixel values of the picture using the selected determined quantization parameter value. 10. A method for decoding a picture of a wide dynamic range, the method being performed with a video coding system comprising at least a decoder, the method comprising: accessing a compressed picture, wherein the compressed picture comprises coded blocks of transformed pixel values using a first set of levels of a set of representational quantization parameter (QP) codes that have been extended into a wider second set of levels using a non-linear mapping function, wherein the set of representational quantization parameter codes comprises at least 32 values, wherein the wider second set of levels depends on a bit-depth of the picture and corresponds to a set of determined quantization parameter (QPd) values, and wherein the wider second set of levels utilizes a mapping of respective representational quantization parameter codes to corresponding determined quantization parameter values;for a block of transformed pixel values of the picture, selecting, with the decoder, at least one representational quantization parameter code from the set of representational quantization parameter codes;for the block of transformed pixel values of the picture, using the mapping to select at a determined quantization parameter value corresponding to the selected representational quantization parameter code; anddequantizing, with the decoder, the block of transformed pixel values of the picture using the selected determined quantization parameter value. 11. The method of claim 10, wherein the picture is a wide dynamic range picture that has a bit depth greater than 8 bits. 12. An encoder configured to code a picture of a wide dynamic range, the encoder being operable with a video coding system, the encoder being operable to: determine a set of representational quantization parameter (QP) codes having at least 32 values, wherein the set of representation quantization parameters codes are within a first set of levels;extend the first set of levels of said representational quantization parameter codes into a second set of levels using a non-linear mapping function, wherein the second set of levels is wider than the first set of levels, depends on an image bit depth, and corresponds to a set of determined quantization parameter (QPd) values, and wherein extending the first set of levels of the representation quantization parameter codes comprises a mapping of respective representational quantization parameter codes to corresponding determined quantization parameter values;for a block of transformed pixel values of the picture, select a representational quantization parameter code from the set of representational quantization parameter codes;for the block of transformed pixel values of the picture, use the mapping to select a determined quantization parameter value for the selected representational quantization parameter code; andquantize the block of transformed pixel values of the picture, with the encoder, using the selected determined quantization parameter value. 13. A decoder configured to decode a picture of a wide dynamic range, the decoder being operable with a video coding system, the decoder being operable to: access a compressed picture, wherein the compressed picture comprises coded blocks of transformed pixel values using a first set of levels of a set of representational quantization parameter (QP) codes that have been extended into a wider second set of levels using a non-linear mapping function, wherein the set of representational quantization parameter codes comprises at least 32 values, wherein the wider second set of levels depends on a bit-depth of the picture and corresponds to a set of determined quantization parameter (QPd) values, and wherein the wider second set of levels utilizes a mapping of respective representational quantization parameter codes to corresponding determined quantization parameter values;for a block of transformed pixel values of the picture, select, with the decoder, at least one representational quantization parameter code from the set of representational quantization parameter codes;for the block of transformed pixel values of the picture, use the mapping to select at a determined quantization parameter value corresponding to the selected representational quantization parameter code; anddequantize, with the decoder, the block of transformed pixel values of the picture using the selected determined quantization parameter value. 14. The decoder of claim 13, wherein the picture is a wide dynamic range picture that has a bit depth greater than 8 bits. 15. The decoder of claim 14, wherein each quantization parameter value is based upon regional information with respect to one or more frames of a picture. 16. A computer program product, stored on a non-transitory computer-readable medium, for decoding pictures of a wide dynamic range, the computer program being operable with a video coding system comprising at least a decoder, the computer program comprising instructions for causing a computer to: access a compressed picture, wherein the compressed picture comprises coded blocks of transformed pixel values using a first set of levels of a set of representational quantization parameter (QP) codes that have been extended into a wider second set of levels using a non-linear mapping function, wherein the set of representational quantization parameter codes comprises at least 32 values, wherein the wider second set of levels depends on a bit-depth of the picture and corresponds to a set of determined quantization parameter (QPd) values, and wherein the wider second set of levels utilizes a mapping of respective representational quantization parameter codes to corresponding determined quantization parameter values;for a block of transformed pixel values of the picture, select, with the decoder, at least one representational quantization parameter code from the set of representational quantization parameter codes;for the block of transformed pixel values of the picture, use the mapping to select a determined quantization parameter value corresponding to the selected representational quantization parameter code; anddequantize, with the decoder, the block of transformed pixel values of the picture using the selected determined quantization parameter value. 17. The computer program product of claim 16, wherein the picture is a wide dynamic range picture that has a bit depth greater than 8 bits. 18. The computer program product of claim 17, wherein each quantization parameter value is based upon regional information with respect to one or more frames of a picture. 19. A method to decode a picture with a decoder, the picture comprising coded blocks of transformed pixel values, the method comprising: for a block of transformed pixel values of the picture, receiving a representational quantization parameter code from a first set of levels of representational quantization parameter codes, the first set of levels of representational quantization parameter codes having at least 32 values;mapping using a non-linear mapping function the received representational quantization parameter code from the first set of levels to a second set of levels for determined quantization parameter values, the second set of levels differing in number of levels from the first set of levels; anddequantizing the block of transformed pixel values of the picture using the determined quantization parameter. 20. The method of claim 19, wherein the non-linear mapping function is linear for mapping a first portion of the first set of levels and non-linear in mapping a second portion of the first set of levels, the second portion comprising level values that are greater than the level values of the first portion. 21. The method of claim 19, wherein the second set of levels has a great number of levels than the first set of levels.
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