US Patent 9723318 Compression and decompression of reference images in a video encoder

Methods and devices transform image data, which are transformed by a compression filter before being compressed and stored in a reference image memory. In an extension, an inverse transformation to that of the compression filter is performed by a decompression filter when image data from the reference memory are read out and decompressed. The methods and devices can be used for image compression methods and image decompression methods that use reference image memories.