SEI Truncation Signaling for Video Bit Depth Conversion

The patent applies preliminary action by performing forward truncation function during encoding to pre-reduce bit depth from first bit depth to second bit depth, and preparing reverse truncation function parameters in SEI messages beforehand. This allows the decoder to reconstruct the original bit depth representation without introducing artifacts, thus improving encoding efficiency while maintaining image quality.

The patent changes the bit depth parameter from a fixed value to a variable that can be converted between first bit depth and second bit depth using forward and reverse truncation functions. The SEI messages carry syntax elements indicating these conversion functions, allowing dynamic parameter adjustment between encoding and decoding stages to resolve the contradiction between encoding efficiency and image quality.

The patent introduces SEI messages as an intermediary carrier that transports forward truncation function parameters and reverse truncation function parameters between encoder and decoder. These messages contain syntax elements that enable the decoder to accurately reconstruct the original data representation, thus reducing data volume while preventing information loss through the intermediary information channel.

The encoder performs forward truncation function preliminarily during encoding to reduce bit depth, and simultaneously prepares the reverse truncation function parameters in advance within SEI messages. This preliminary action ensures that the data volume is reduced while the information needed for accurate reconstruction is preserved and transmitted to the decoder.