Methods of escape pixel coding in index map coding

A method of video encoding, comprising:

• obtaining samples of a current block that is to be coded according to a palette coding mode;
• determining a palette table associated with the current block, each entry of the palette table including values of different color components in a color space;
• determining a palette index map for coding the samples of the current block, including palette coded samples and escape samples of the current block, according to the palette table, the palette index map including respective index values for all the samples of the current block, each index value of the index values indicating whether a corresponding sample is one of the palette coded samples having values of an entry of the palette table or one of the escape samples having values not included in the palette table;
• generating, by processing circuitry of a encoder, coded data of the current block according to the palette coding mode, the coded data including information indicating at least the palette index map and the escape samples, values of the different color components of the escape samples being separately grouped into groups of values on a color-by-color basis, each group containing values of a single color component, and the groups of values being sequentially arranged one group after another in the coded data;
• and
• generating, by the processing circuitry of the encoder, a bitstream carrying the coded data, wherein
• the escape samples of the current block are signaled at an end of coded palette data for the current block, and
• the coded palette data includes the escape samples and parameters specifying one or more of a palette run type, a palette index, a palette run, escape flags, and the palette table associated with the current block.

An apparatus for video decoding, comprising:

• processing circuitry configured to
• receive a bitstream carrying coded data of a current block, the current block being coded according to a palette coding mode;
• determine a palette table associated with the current block, each entry of the palette table including values of different color components in a color space;
• determine a palette index map for the current block from the coded data, the palette index map including respective index values for all samples of the current block, including palette coded samples and escape samples of the current block, each index value of the index values indicating whether a corresponding sample is one of the palette coded samples having values of an entry of the palette table or one of the escape samples having values not included in the palette table;
• decode the palette coded samples of the current block according the palette index map and the palette table;
• obtain all the escape samples of the current block from the coded data, values of the different color components of the escape samples being separately grouped into groups of values on a color-by-color basis, each group containing values of a single color component, and the groups of values being sequentially arranged one group after another in the coded data;
• and
• decode the current block according to the coded samples and the escape samples of the current block, wherein
• the escape samples of the current block are signaled at an end of coded palette data for the current block, and
• the coded palette data includes the escape samples and parameters specifying one or more of a palette run type, a palette index, a palette run, escape flags, and the palette table associated with the current block.