Hardware efficient sparse FIR filtering in layered video coding
In a decoder, a processor extracts a control map of false contour filtering from a part of a multi-layer video signal that includes a low dynamic range image mapped from an original high-dynamic range (HDR) image. It determines one or more filter parameters for a sparse finite-impulse-response (FIR) filter, where the one or more filter parameters relate to at least in part on the control map of false contour filtering and a predicted image predicted from the low dynamic range image. It applies the sparse FIR filter to filter pixel values in a portion of the predicted image based at least in part on the control map of false contour filtering, and it reconstructs a version of the original HDR image based at least in part on the portion of the predicted image as filtered by the FIR filter.
1. In a decoder comprising one or more processors, a method, comprising:
extracting a control map of false contour filtering from a part of a multi-layer video signal that includes a low dynamic range image mapped from an original high-dynamic range (HDR) image;
determining one or more filter parameters for a sparse finite-impulse-response (FIR) filter, the one or more filter parameters relating to at least in part on the control map of false contour filtering and a predicted image predicted from the low dynamic range image;
applying the sparse FIR filter to filter pixel values in a portion of the predicted image based at least in part on the control map of false contour filtering; and
reconstructing a version of the original HDR image based at least in part on the portion of the predicted image as filtered by the FIR filter.
2. The method as recited in claim 1 , further comprising:
extracting the one or more filter parameters for the sparse FIR filter from a part of the multi-layer video signal that includes the low dynamic range image.
3. The method as recited in claim 1 , wherein the low dynamic range image is encoded as a part of base-layer (BL) image data in the multi-layer video signal.
4. The method as recited in claim 1 , wherein one of the one or more filter parameters represents a number of taps in the sparse FIR filter; and wherein the number of taps is constrained to be no more than a fixed number.
5. The method as recited in claim 1 , wherein a second different sparse FIR filter is used to filter a second different portion of the predicted image.
6. The method as recited in claim 1 , wherein the sparse FIR filter is used to filter an entire area of the predicted image.
7. The method as recited in claim 1 , wherein the sparse FIR filter is used to filter pixel values for a specific channel in a plurality of channels of a color space.
8. The method as recited in claim 7 , 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.
9. A non-transitory computer readable storage medium, storing software instructions, which when executed by one or more processors causes performance of the method recited in claim 1 .
10. A computing device comprising one or more processors and one or more storage media, storing a set of instructions, which when executed by one or more processors cause performance of the method recited in claim 1 .