Restoration for video coding with self-guided filtering and subspace projection
AssigneeGoogle Inc.
InventorDebargha Mukherjee
Life of this patent
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Abstract
Restoring a degraded frame resulting from reconstruction of a source frame is described. A method includes generating, using first restoration parameters, a first guide tile for a degraded tile of the degraded frame, determining a projection parameter for a projection operation, and encoding, in an encoded bitstream, the first restoration parameters and the projection parameter. The projection operation relates differences between a source tile of the source frame and the degraded tile to differences between the first guide tile and the degraded tile.
Claims18
A method of restoring a degraded frame resulting from reconstruction of a source frame, the method comprising:
- generating, using first restoration parameters, a first guide tile for a degraded tile of the degraded frame, wherein the generating the first guide tile comprising:
- determining, using pixel values of the degraded tile in a second window centered at the pixel, an average baseline value that is approximated by:
- assigning respective weights to at least some pixel locations of the second window such that a sum of the respective weights is a power of 2;
- calculating a weighted sum;
- and
- bit-shifting the weighted sum by the power of 2;
- determining a projection parameter for a projection operation, the projection operation relating differences between a source tile of the source frame and the degraded tile to differences between the first guide tile and the degraded tile;
- and
- encoding, in an encoded bitstream, the first restoration parameters and the projection parameter.
An apparatus for restoring a degraded frame resulting from reconstruction of a source frame, comprising:
- a processor configured to execute instructions stored in a non-transitory storage medium to:
- generate, using first restoration parameters, a first guide tile for a first degraded tile of the degraded frame, wherein to generate the first guide tile comprises to:
- determine, using pixel values of the degraded tile in a second window centered at the pixel, an average baseline value that is approximate by steps comprising:
- assigning respective weights to at least some pixel locations of the second window such that a sum of the respective weights is a power of 2;
- calculating a weighted sum;
- and
- bit-shifting the weighted sum by the power of 2;
- determine a projection parameter for a projection operation;
- and
- encode, in an encoded bitstream, the first restoration parameters and the projection parameter.
A method of restoring a degraded frame, the method comprising:
- determining, from an encoded bitstream, a first projection parameter and a second projection parameter;
- determining, from the encoded bitstream, first restoration parameters and second restoration parameters;
- generating, using the first restoration parameters, a first guide tile for a degraded tile of the degraded frame, wherein the generating the first guide tile comprising:
- determining, using pixel values of the degraded tile in a window centered at the pixel, an average baseline value that is approximate by:
- assigning respective weights to at least some pixel locations of the window such that a sum of the respective weights is a power of 2;
- calculating a weighted sum;
- and
- bit-shifting the weighted sum by the power of 2;
- generating, using the second restoration parameters, a second guide tile for the degraded tile;
- and
- performing a projection operation using the first guide tile, the second guide tile, the first restoration parameters, and the second restoration parameters to generate a reconstructed tile of a reconstructed frame.
Dependencies are inferred from the claim text.