Luminance based coding tools for video compression
Sample data and metadata related to spatial regions in images may be received from a coded video signal. It is determined whether specific spatial regions in the images correspond to a specific region of luminance levels. In response to determining the specific spatial regions correspond to the specific region of luminance levels, signal processing and video compression operations are performed on sets of samples in the specific spatial regions. The signal processing and video compression operations are at least partially dependent on the specific region of luminance levels.
1 . An apparatus for processing a spatial region of a video image represented in a video signal, the apparatus comprising:
an input for receiving an input image in a video bitstream comprising luminance and chroma pixel values; and
a processor, wherein the processor:
determines a luminance indicator of a spatial image region in the input image based on a plurality of luminance pixel values in the spatial image region, wherein the luminance indicator indicates that a specific partition corresponds to a specific range of luminance levels within two or more ranges of luminance levels in the spatial image region;
determines one or more filtering parameters for a deblocking filter, wherein the filtering parameters depend on the luminance indicator in the spatial image region; and
applies the deblocking filter to the spatial image region to generate a filtered image region, wherein the deblocking filter with the one or more filtering parameters is applied to filter the plurality of luminance pixel values in the spatial image region to generate a plurality of filtered luminance pixel values in the filtered image region.
2 . The apparatus of claim 1 wherein the luminance indicator is determined based on an average of the plurality of luminance pixel values in the spatial image region.
3 . The apparatus of claim 1 , wherein a parameter from the one or more filtering parameters for the deblocking filter comprises an offset to another operational parameter for deblocking.
4 . The apparatus of claim 1 , wherein the processor further determines, based at least in part on the luminance indicator, values of operational parameters used in one or more signal processing operations related to the spatial image region of the input image.
5 . The apparatus of claim 4 , wherein a determined operational parameter used in signal processing operations related to the spatial image region of the input image comprises an offset to another operational parameter for deblocking.
6 . The apparatus of claim 1 , wherein the deblocking filter is selected from a first deblocking filter or a second deblocking filter stronger than the first deblocking filter based on the luminance indicator.
7 . The apparatus of claim 4 , wherein the one or more signal processing operations include performing a smoothing operation on pixels in the spatial image region that is enabled by a set of smoothing operational parameters whose values are selected based at least in part on the two or more ranges of luminance levels.