Method of palette index signaling for image and video coding

An apparatus for coding a block of video data using palette coding, the apparatus comprising one or more electronic circuits configured to:

• receive input data associated with a current block;
• determine whether there is only one single palette index in the current block based on one or a combination of a first syntax element corresponding to a first number of predicted palette, a second syntax element corresponding to a second number of signaled palette, a third syntax element corresponding to CU_level_escape_flag indicating whether there is any Escape sample in the current block and a forth syntax element corresponding to a maximum possible value for the palette index for the current block;
• and
• if there is only one single palette index in the current block, omit signaling a current palette index map for the current block at an encoder side or omit parsing any syntax for decoding the current palette index map for the current block at a decoder side.

A method for coding a block of video data using palette coding in a video coding system, wherein the video coding system incorporates a first syntax element to indicate whether there is only one single palette index in the block of video data based on one or a combination of a syntax element corresponding to a first number of predicted palette, a syntax element corresponding to a second number of signaled palette, a syntax element corresponding to CU_level_escape_flag indicating whether there is any Escape sample in the current block and a syntax element corresponding to a maximum possible value for the palette index for the current block, and a second syntax element to indicate said one single palette index if the first syntax element is asserted, the method comprising:

• receiving input data associated with a current block;
• after signaling or parsing a current palette table for the current block, deriving corresponding total palette size of the current block including Escape index at an encoder side or at a decoder side;
• and
• if the total palette size of the current block including the Escape index is equal to one, omitting signaling a current first syntax element and a current second syntax element at the encoder side or inferring respective values for the current first syntax element and the current second syntax element at the decoder side.