Indexed color history in image coding

摘要

An encoder may implement an indexed color history that stores color values for previously encoded pixels. The encoder may obtain a current pixel or current group of pixels for encoding and determine whether to encode the current pixel using the indexed color history. In doing so, the encoder may compare a color value of the current pixel with color values of the previously coded pixels to determine whether the current pixel is sufficiently similar to a previously coded pixel color value, e.g., by satisfying one or more similarity criteria. When the similarity criteria are satisfied, the encoder may encode the current pixel as an index value referencing the entry in the indexed color history storing a color value that satisfies the similarity criteria. When the similarity criteria are not satisfied, the encoder may encode the current pixel using another encoding method or technique.

主权项

1. A system comprising:
a memory storing:
an indexed color history comprising an entry storing a color value of a previously coded pixel; encoding circuitry in communication with the memory and configured to:
obtain a current pixel for encoding;determine whether to encode the current pixel by referencing the indexed color history by determining when a color value of the current pixel is within a difference threshold of the color value of the previously coded pixel; andwhen it is determined to encode the current pixel using the indexed color history:
encode the pixel as an index value referencing the entry in the indexed color history.