Encoding Perceptually-Quantized Video Content In Multi-Layer VDR Coding

Patent metadata

Field	Value
Publication number	US-2016014420-A1
Application number	US-201414771101-A
Country	US
Kind code	A1
Filing date	Mar 25, 2014
Priority date	Mar 26, 2013
Publication date	Jan 14, 2016
Grant date	—

Abstract

Input VDR images are received. A candidate set of function parameter values for a mapping function is selected from multiple candidate sets. A set of image blocks of non-zero standard deviations in VDR code words in at least one input VDR image is constructed. Mapped code values are generated by applying the mapping function with the candidate set of function parameter values to VDR code words in the set of image blocks in the at least one input VDR image. Based on the mapped code values, a subset of image blocks of standard deviations below a threshold value in mapped code words is determined as a subset of the set of image blocks. Based at least in part on the subset of image blocks, it is determined whether the candidate set of function parameter values is optimal for the mapping function to map the at least one input VDR image.

First claim

1 - 29 . (canceled)

30 . A method, comprising:
receiving a sequence of input images; selecting a candidate set of function parameter values for a mapping function from a plurality of candidate sets of function parameter values for the mapping function; dividing each input image into image blocks; determining, for each image block, a standard deviation of pixel values in that block; constructing a set of image blocks, from among said image blocks, having non-zero standard deviation in pixel values for at least one input image in the sequence of input images; generating mapped image blocks by applying the mapping function with the candidate set of function parameter values to the pixel values in the set of image blocks in the at least one input image; determining, for each mapped image block, a standard deviation of the pixel values in that block; constructing a subset of mapped image blocks from among the mapped image blocks, each mapped image block of said subset having a standard deviation larger than a predefined threshold value; and
determining, based on a comparison between the number of mapped image blocks with non-zero standard deviations in said subset relative and the number of image blocks in said set, whether the candidate set of function parameter values is optimal for the mapping function to map the at least one input image.

31 . The method as recited in claim 30 , wherein a bit depth of the input images is equal to or larger than 12 bits.

32 . The method as recited in claim 30 , wherein said determining whether the candidate set of function parameter values is optimal for the mapping function to map the at least one input image is based on whether the number of mapped image blocks in said subset is equal to the number of image blocks in said set.

33 . The method as recited in claim 30 , further comprising:
in response to determining that the candidate set of function parameter values is optimal for the mapping function to map the at least one input image, determining whether the candidate set of function parameter values should be used as an overall optimal set of function parameter values by the mapping function to map a plurality of input images that include the at least one input image.

34 . The method as recited in claim 33 , further comprising:
in response to determining that the candidate set of function parameter values should be used as an overall optimal set of function parameter values by the mapping function to map the plurality of input images that include the at least one input image, performing: generating a plurality of mapped images that correspond to the plurality of input images by applying the mapping function with the overall optimal set of function parameter values to the plurality of images; compressing the plurality of mapped images as base-layer (BL) image data into an output multi-layer video signal.

35 . The method as recited in claim 34 , further comprising:
decoding the BL image data; generating prediction image data based at least in part on an inverse mapping of the BL image data; generating residual values based at least in part on the prediction image data and the at least one input image; applying non-linear quantization to the residual values to generate enhancement layer (EL) image data, the residual values comprising high bit depth values, and the EL image data comprising low bit depth values; and compressing the EL image data into the output multi-layer video signal.

36 . The method as recited in claim 35 , further comprising outputting metadata comprising the determined overall optimal set of function parameter values as a part of the output multi-layer video signal to a downstream device.

37 . The method as recited in claim 35 , wherein the inverse mapping of the BL image data is based on one or more lookup tables generated from the mapping function with the overall optimal set of function parameter values.

38 . The method as recited in claim 30 , wherein the mapping function represents at least one of power functions, linear quantization functions, or piece-wise linear quantization functions.

39 . The method as recited in claim 30 , wherein the candidate set of function parameter values for the mapping function represents a candidate exponent value for a power function.

40 . The method as recited in claim 30 , wherein the candidate set of function parameter values for the mapping function represents one or more pivots for a piece-wise linear quantization function.

41 . The method as recited in claim 30 , wherein the set of image blocks of non-zero standard deviations is computed with the code words within a specific value range in a plurality of value ranges.

42 . The method as recited in claim 41 , wherein the plurality of value ranges comprise one or more of high value ranges, medium value ranges, or low value ranges, wherein the pixel values in the high value ranges have higher values than the pixel values in the medium value ranges and low value ranges and wherein the pixel values in the medium value ranges have higher values than the pixel values in the low value ranges and lower values than the pixel values in the high value ranges.

43 . The method as recited in claim 42 , further comprising:
computing a set of statistical values for the set of image blocks of non-zero standard deviations, wherein an individual statistical value in the set of statistical values represents at least one of: an arithmetic average, an arithmetic medium, a geometric average, a geometric medium, a maximum, or a minimum in pixel values of an individual image block in the set of image blocks of non-zero standard deviations; generating, based on the set of statistical values, the plurality of pixel value ranges.

44 . The method as recited in claim 30 , wherein the set of image blocks of non-zero standard deviations is computed with the pixel values for a specific channel in a plurality of channels of a color space.

45 . The method as recited in claim 44 , wherein the plurality of channels comprises one or more of a luminance channel, a chroma channel, a red color channel, a blue color channel, a green color channel, or other primary channels.

46 . The method as recited in claim 44 , wherein a different mapping function is used to map different pixel values for a different channel in the plurality of channels.

47 . The method as recited in claim 30 , wherein base layer (BL) image data derived from the sequence of input images is compressed by a first 8 bit encoder into a multi-layer video signal, and wherein enhancement layer (EL) image data derived from the sequence of input images is compressed by a second 8 bit encoder in the multi-layer encoder into the multi-layer video signal.

48 . The method as recited in claim 47 , wherein at least one of the first 8 bit encoder and the second 8 bit encoder comprises at least one of: an advanced video coding (AVC) encoder, a Moving Picture Experts Group (MPEG)-2 encoder, or a High Efficiency Video Coding (HEVC) encoder.

49 . The method as recited in claim 30 , wherein the sequence of input images has been perceptually encoded.

50 . The method as recited in claim 30 , wherein at least one of the non-zero standard deviations is represented with one of non-zero max-min differences, non-zero variances, or smoothness measurement values each of which corresponds to a non-zero standard deviation.

51 . An encoder performing with a processor

Assignees

• Dolby Lab Licensing Corp

Inventors

• Su Guan-Ming
• Chen Qian
• Koepfer Hubert

Classifications

• H04N19/50

  using predictive coding (H04N19/61 takes precedence) · CPC title

• H04N19/136

  Incoming video signal characteristics or properties · CPC title

• H04N19/30 Primary

  using hierarchical techniques, e.g. scalability (H04N19/63 takes precedence) · CPC title

• H04N19/70

  characterised by syntax aspects related to video coding, e.g. related to compression standards · CPC title

• H04N19/44

  Decoders specially adapted therefor, e.g. video decoders which are asymmetric with respect to the encoder · CPC title