Low complexity mixed domain collaborative in-loop filter for lossy video coding

A system comprising:

• a video encoding apparatus for encoding a frame of a video;
• and
• a video decoding apparatus for decoding a frame of a video,
• wherein the system comprises a processor and a non-transitory storage medium carrying a program code,
• wherein the program code, when executed by the processor, causes the system to carry out a programmed processor-implemented method comprising:
• reconstructing the frame to render a reconstructed frame;
• determining a set of filter parameters;
• and
• filtering, in a frequency domain and a pixel domain, a block of the reconstructed frame based on the set of filter parameters to obtain a filtered block of the frame,
• wherein the video encoding apparatus is configured to determine the set of filter parameters, during the determining, in a same way as the video decoding apparatus, and
• wherein the filtering a block of the reconstructed frame comprises performing, for the block of the reconstructed frame:
• determining a group of pixel-domain patches that are similar to the block,
• determining first parameters based on the group of pixel-domain patches,
• determining second parameters based on signaling information of the block,
• performing collaborative filtering of the group of pixel-domain patches in the frequency domain to obtain a group of filtered pixel-domain patches, and
• performing collaborative filtering of the filtered pixel-domain patches in pixel domain along pixel-domain patches with same spatial coordinates from different groups.

A non-transitory computer-readable medium comprising computer-executable instructions, wherein the computer-executable instructions, when executed by a computer, cause the computer to carry out a method for encoding or decoding a frame of a video, the method comprising:

• reconstructing the frame of the video to render a reconstructed frame;
• determining a set of filter parameters;
• and
• filtering, in a pixel domain and a frequency domain, a block of the reconstructed frame based on the determined set of filter parameters to obtain a filtered block of the frame,
• wherein the filtering a block of the reconstructed frame comprises performing, for the block of the reconstructed frame:
• determining a group of pixel-domain patches that are similar to the block,
• determining first parameters based on the group of pixel-domain patches,
• determining second parameters based on signaling information of the block,
• performing collaborative filtering of the group of pixel-domain patches in the frequency domain to obtain a group of filtered pixel-domain patches, and
• performing collaborative filtering of the filtered pixel-domain patches in pixel domain along pixel-domain patches with same spatial coordinates from different groups.

A method for encoding or decoding a frame of a video, the method comprising:

• reconstructing the frame of the video to render a reconstructed frame;
• determining a set of one or more filter parameters;
• and
• filtering, in a pixel domain and a frequency domain, a block of the reconstructed frame based on the determined set of filter parameters to obtain a filtered block of the frame,
• wherein the filtering a block of the reconstructed frame comprises performing, for the block of the reconstructed frame:
• determining a group of pixel-domain patches that are similar to the block,
• determining first parameters based on the group of pixel-domain patches,
• determining second parameters based on signaling information of the block,
• performing collaborative filtering of the group of pixel-domain patches in the frequency domain to obtain a group of filtered pixel-domain patches, and
• performing collaborative filtering of the filtered pixel-domain patches in pixel domain along pixel-domain patches with same spatial coordinates from different groups.