Adaptive chroma downsampling and color space conversion techniques

Abstract

A method of adaptive chroma downsampling is presented. The method comprises converting a source image to a converted image in an output color format, applying a plurality of downsample filters to the converted image and estimating a distortion for each filter chose the filter that produces the minimum distortion. The distortion estimation includes applying an upsample filter, and a pixel is output based on the chosen filter. Methods for closed loop conversions are also presented.

1 .- 28 . (canceled) 
     
     
         29 . A video processor, comprising:
 a decoder for decoding an image from a compressed video sequence, wherein the compressed video sequence includes side information relating to a filter selection; and   a format converter for converting the decoded image, including a color format converter and a plurality of upsampling filters, and wherein the side information is used at least in part to determine which of the plurality of upsampling filters are used to upsample a chroma channel of the decoded images.   
     
     
         30 . The video processor of  claim 29 , wherein the color format converter converts a luma-chroma color format into an RGB color format. 
     
     
         31 . The video processor of  claim 29 , wherein the side information indicates which of a plurality of possible upsample filters best matches a downsample filter selected from a plurality of downsample filters and used to encode the image in the compressed video sequence. 
     
     
         32 . The video processor of  claim 29 , wherein the side information is encoded in the compressed video sequence in a Supplemental Enhancement Information (SEI) message. 
     
     
         33 . The video processor of  claim 31 , wherein the SEI message is a post-filter hint SEI message. 
     
     
         34 . The video processor of  claim 31 , wherein the SEI message is a chroma resampling filter hint SEI message. 
     
     
         35 . The video processor of  claim 29 , wherein the side information includes a color transform matrix used in the color format converter. 
     
     
         36 . The video processor of  claim 29 , wherein the side information includes information about the filters used in a downsampling filter optimization process at an encoder for the compressed video sequence. 
     
     
         37 . A method for processing compressed video, comprising:
 decoding an image from a compressed video sequence including extracting, from the compressed video sequence, side information specifying a filter selection relating to the image;   converting a format of the image including converting a color format of the image and upsampling a chroma channel of the image, wherein the side information is used to determine which of a plurality of upsampling filters to use in the upsampling.   
     
     
         38 . The method of  claim 37 , wherein the converting a color format converts a luma-chroma color format into an RGB color format. 
     
     
         39 . The method of  claim 37 , wherein the side information indicates which of a plurality of possible upsample filters best matches a downsample filter selected from a plurality of downsample filters and used to encode the image in the compressed video sequence. 
     
     
         40 . The method of  claim 37 , wherein the side information is encoded in the compressed video sequence in a Supplemental Enhancement Information (SEI) message. 
     
     
         41 . The method of  claim 40 , wherein the SEI message is a post-filter hint SEI message. 
     
     
         42 . The method of  claim 40 , wherein the SEI message is a chroma resampling filter hint SEI message. 
     
     
         43 . The method of  claim 37 , wherein the side information includes a color transform matrix used in the converting a color format. 
     
     
         44 . The method of  claim 37 , wherein the side information includes information about the filters used in a downsampling filter optimization process at an encoder for the compressed video sequence. 
     
     
         45 . A non-transitory computer readable medium comprising instructions that, when executed on a computer, cause the computer to:
 decode an image from a compressed video sequence including extracting, from the compressed video sequence, side information specifying a filter selection relating to the image;   convert a format of the image, where the converting includes converting a color format of the image and upsampling a chroma channel of the image, wherein the side information is used to determine which of a plurality of upsampling filters to use in the upsampling.   
     
     
         46 . The medium of  claim 45 , wherein the color format converter converts a luma-chroma color format into an RGB color format. 
     
     
         47 . The medium of  claim 45 , wherein the side information includes a color transform matrix used in the color format converter. 
     
     
         48 . The medium of  claim 45 , wherein the side information includes information about the filters used in a downsampling filter optimization process at an encoder for the compressed video sequence.