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Patent

Encoding perceptually-quantized video content in multi-layer vdr coding

25 Mar 2014-
TL;DR: In this article, a set of image blocks of non-zero standard deviations in VDR code words in at least one input VDR image is constructed, and a candidate set of function parameter values for a mapping function is selected from multiple candidate sets.
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.
Citations
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Patent
16 Jun 2014
TL;DR: In this paper, a polynomial approximation technique for representing reverse-mapping functions and chromaticity translation schemes to reduce color shifts are also presented, where the reverse mapping function may be transmitted to a decoder as a look-up table or it may be approximated using a piecewise approximation.
Abstract: An encoder receives an input enhanced dynamic range (EDR) image to be coded in a layered representation. Input images may be gamma-coded or perceptually-coded using a bit-depth format not supported by one or more video encoders. The input image is remapped to one or more quantized layers to generate output code words suitable for compression using the available video encoders. Algorithms to determine optimum function parameters for linear and non-linear mapping functions are presented. Given a mapping function, the reverse mapping function may be transmitted to a decoder as a look-up table or it may be approximated using a piecewise polynomial approximation. A polynomial approximation technique for representing reverse-mapping functions and chromaticity translation schemes to reduce color shifts are also presented.

52 citations

Patent
Jan Froehlich1, Robin Atkins1, Qiuwei Wang1, Guan-Ming Su1, Yin Peng1 
24 Sep 2015
TL;DR: In this article, a color cross-talk transformation after the RGB/XYZ to LMS transformation is proposed to increase luma and chroma correlation for color appearance models, but improves perceptual uniformity and overall coding efficiency for wide color gamut.
Abstract: Compared to traditional gamma-coded video, perceptually quantized video provides greater flexibility for the transmission and display management of high-dynamic range video, but it does not compresses as efficiently using existing standard codecs. Techniques are described to improve the coding efficiency of perceptually coded video by applying a color cross-talk transformation after the RGB/XYZ to LMS transformation. Such a transform increases luma and chroma correlation for color appearance models, but improves perceptual uniformity and overall coding efficiency for wide color gamut, HDR, signals.

25 citations

Patent
18 Jan 2018
TL;DR: In this paper, a portion of source video content is adaptively reshaped, based on the selected adaptive reshaping function to generate a part of reshaped video content, which is represented by the one or more source images.
Abstract: Statistical values are computed based on received source images. An adaptive reshaping function is selected for one or more source images based on the one or more statistical values. A portion of source video content is adaptively reshaped, based on the selected adaptive reshaping function to generate a portion of reshaped video content. The portion of source video content is represented by the one or more source images. An approximation of an inverse of the selected adaptive reshaping function is generated. The reshaped video content and a set of adaptive reshaping parameters defining the approximation of the inverse of the selected adaptive reshaping function are encoded into a reshaped video signal. The reshaped video signal may be processed by a downstream recipient device to generate a version of reconstructed source images, for example, for rendering with a display device.

21 citations

Patent
01 Mar 2016
TL;DR: In this article, a noise-mask generation process is applied to the input image to generate a noise mask image which characterizes each pixel in the input images in terms of its perceptual relevance in masking quantization noise.
Abstract: A content-adaptive quantizer processor receives an input image with an input bit depth. A noise-mask generation process is applied to the input image to generate a noise mask image which characterizes each pixel in the input image in terms of its perceptual relevance in masking quantization noise. A noise mask histogram is generated based on the input image and the noise mask image. A masking-noise level to bit-depth function is applied to the noise mask histogram to generate minimal bit depth values for each bin in the noise mask histogram. A codeword mapping function is generated based on the input bit depth, a target bit depth, and the minimal bit depth values. The codeword mapping function is applied to the input image to generate an output image in the target bit depth.

21 citations

Patent
Su Guan-Ming1
03 May 2018
TL;DR: In this article, the in-loop, region-based, reshaping for the coding of high-dynamic range video is described, using a high bit-depth buffer to store input data and previously decoded reference data.
Abstract: Systems and methods are disclosed for in-loop, region-based, reshaping for the coding of high-dynamic range video. Using a high bit-depth buffer to store input data and previously decoded reference data, forward and backward, in-loop, reshaping functions allow video coding and decoding to be performed at a target bit depth lower than the input bit depth. Methods for the clustering of the reshaping functions to reduce data overhead are also presented.

20 citations

References
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Patent
21 Apr 2011
TL;DR: In this paper, a first image stream has a first dynamic range and a first color space, and a second image stream is encoded to obtain an encoded image stream, which is decoded to obtain a decoded image stream.
Abstract: A first image stream has a first dynamic range and a first color space. First and the second image streams are received in a layered codec. The second image stream has a second dynamic range, which is higher than the first dynamic range. The first image stream is in the codec's base layer; the second image stream is in its enhancement layer. The first image stream is encoded to obtain an encoded image stream, which is decoded to obtain a decoded image stream. The decoded image stream is converted from the first non-linear or linear color space to a second, different color space to obtain a color converted image stream. A higher dynamic range image representation of the color converted image stream is generated to obtain a transformed image stream. Inverse tone mapping parameters are generated based on the transformed image stream and the second image stream.

187 citations

Patent
14 May 2007
TL;DR: In this paper, a method of automatic mapping of image data includes representing image data for an image as luminance values (104), determining a key value as a function of an average luminance value of the image and of minimum and maximum luminances values of image (108), generating offset-adjusted luminance, and computing a tone reproduction curve for at least a region of an image which includes applying a mapping function to the offset adjusted luminance.
Abstract: A method of automatic mapping of image data includes representing image data for an image as luminance values (104), determining a key value as a function of an average luminance value of the image and of minimum and maximum luminance values of the image (108), generating offset-adjusted luminance values including applying an offset to each of the luminance values, the offset being a function of the determined key value, and computing a tone reproduction curve for at least a region of the image which includes applying a mapping function to the offset-adjusted luminance values.

124 citations

Patent
23 Aug 2011
TL;DR: In this paper, an input video signal that is represented in a first color space with a first colour gamut, which is related to a first dynamic range, is converted to a video signal representing in a second color space and associated with a second dynamic range; at least two (e.g., three) color-related components of the converted video signal are mapped over the second dynamic ranges.
Abstract: Enhancing image dynamic range is described. An input video signal that is represented in a first color space with a first color gamut, which is related to a first dynamic range, is converted to a video signal that is represented in a second color space with a second color gamut. The second color space is associated with a second dynamic range. At least two (e.g., three) color-related components of the converted video signal are mapped over the second dynamic range.

124 citations

Patent
07 Sep 2006
TL;DR: In this paper, a method for encoding high dynamic range (HDR) images involves providing a lower dynamic range image, generating a prediction function for estimating the values for pixels in the HDR image based on the values of corresponding pixels in LDR image, and obtaining a residual frame based on differences between the pixel values of HDR image and estimated pixel values.
Abstract: A method for encoding high dynamic range (HDR) images involves providing a lower dynamic range (LDR) image, generating a prediction function for estimating the values for pixels in the HDR image based on the values of corresponding pixels in the LDR image, and obtaining a residual frame based on differences between the pixel values of the HDR image and estimated pixel values The LDR image, prediction function and residual frame can all be encoded in data from which either the LDR image of HDR image can be recreated

116 citations

Patent
06 Oct 2006
TL;DR: In this paper, a method and apparatus for decoding an encoded baseline video stream and an enhancement stream is provided for decoding, upscaling and enhancing by applying adaptive filters specified by the enhancement stream.
Abstract: A method and apparatus is provided for decoding an encoded baseline video stream and an enhancement stream. The baseline video stream is decoded, upscaled and enhanced by applying adaptive filters specified by the enhancement stream. Baseline upscaled images are then coded to motion compensate enhanced high resolution images using previously decoded enhanced images, thus recycling these enhanced images. The enhancement stream provides the best predictor method for the decoder to combine blocks from previous enhanced images and upscaled images to produce a motion compensated enhanced image. Likewise, forward and backward motion compensated images are blended according to feature classification and filter extraction methods provided by the enhancement stream to produce a bidirectionally predicted frame. Lastly, the decoder applies residual data from the enhancement stream to produce a completed enhanced image.

108 citations