VIDEO ENCODING MODE DECISIONS ACCORDING TO CONTENT CATEGORIES

In some embodiments, encoding modes for a video image block are enabled according to similarity measures of the block with respect to multiple content categories. Content categories may identify potentially overlapping content types such as sky, water, grass, skin, and red content. In a priority mode, the encoding modes specified by a priority content category (e.g. a red category) are selectively enabled for the block, regardless of the block's similarity to other (non-priority) content categories, provided the block is sufficiently similar to the priority category. In a dominant mode, the encoding modes enabled by a maximum-similarity content category are enabled for the block. In an all-inclusive mode, any mode enabled by any sufficiently-similar content category is enabled for the block. Enabled encoding modes may be further evaluated for selection for the block. Encoding modes may include inter/intra modes, macroblock partition sizes, and intra-prediction directions.