Lossless Compression in HEVC with Integer-to-Integer Transforms
This work addresses lossless video compression for HEVC users, but it is incremental as it builds on prior approaches like DPCM.
The paper tackled the problem of inefficient lossless compression in HEVC by exploring integer-to-integer transforms as an alternative to existing methods, achieving competitive results in experiments with the HEVC reference software.
Many approaches have been proposed to support lossless coding within video coding standards that are primarily designed for lossy coding. The simplest approach is to just skip transform and quantization and directly entropy code the prediction residual, which is used in HEVC version 1. However, this simple approach is inefficient for compression. More efficient approaches include processing the residual with DPCM prior to entropy coding. This paper explores an alternative approach based on processing the residual with integer-to-integer (i2i) transforms. I2i transforms map integers to integers, however, unlike the integer transforms used in HEVC for lossy coding, they do not increase the dynamic range at the output and can be used in lossless coding. Experiments with the HEVC reference software show competitive results.