Palette coding for screen content coding

Abstract

Sketch copy mode may be used to code blocks comprising irregular lines, syntax redundancy may be removed from blocks with special characteristics, and/or run value coding may be simplified. The parsing dependencies in palette coding design may be removed. For example, the context modeling dependency of the syntax element palette_transpose_flag be removed, for example, by simplifying the corresponding context model. The context modeling of the syntax element palette mode may be removed, for example, by using run-length coding without using context. The syntax parsing dependencies and/or the syntax signaling dependencies that are related with escape color signaling may be removed. A palette table generation process may handle input screen content video with high bit depths, for example, at the encoder side.

1 - 20 . (canceled) 
     
     
         21 . A method for video decoding, the method comprising:
 receiving a scan direction indication for a coding unit (CU) in video data, the scan direction indication indicating a palette coding scan direction associated with the CU, wherein the scan direction indication is coded with a single context; and   decoding the CU based on the first scan direction indication.   
     
     
         22 . The method of  claim 21 , wherein a context value for decoding the scan direction indication for the CU is independent of a palette coding scan direction associated with another CU. 
     
     
         23 . The method of  claim 21 , wherein the CU is a first CU, and a context value for decoding the scan direction indication for the first CU is independent of a palette coding scan direction associated with a second CU neighboring the first CU. 
     
     
         24 . The method of  claim 21 , wherein the CU is a first CU, and the scan direction indication for the first CU is coded with a context that does not depend on a palette coding scan direction associated with a second CU neighboring the first CU. 
     
     
         25 . The method of  claim 21 , wherein the scan direction indication for the CU is a palette transpose flag configured to indicate whether a horizontal traverse scan or a vertical traverse scan is applied for scanning palette indices of samples in the CU. 
     
     
         26 . The device for video decoding, comprising:
 a processor configured to:
 receive a scan direction indication for a coding unit (CU) in video data, the scan direction indication indicating a palette coding scan direction associated with the CU, wherein the scan direction indication is coded with a single context; and 
 decode the CU based on the scan direction indication. 
   
     
     
         27 . The device of  claim 26 , wherein a context value for decoding the scan direction indication for the CU is independent of a palette coding scan direction associated with another CU. 
     
     
         28 . The device of  claim 26 , wherein the CU is a first CU, and a context value for decoding the scan direction indication for the first CU is independent of a palette coding scan direction associated with a second CU neighboring the first CU. 
     
     
         29 . The device of  claim 26 , wherein the CU is a first CU, and the scan direction indication for the first CU is coded with a context that does not depend on a palette coding scan direction associated with a second CU neighboring the first CU. 
     
     
         30 . The device of  claim 26 , wherein the scan direction indication for the CU is a palette transpose flag configured to indicate whether a horizontal traverse scan or a vertical traverse scan is applied for scanning palette indices of samples in the CU. 
     
     
         31 . A method for video encoding, the method comprising:
 determining a palette coding scan direction for a coding unit (CU); and   encoding a scan direction indication configured to indicate the determined palette coding scan direction associated with the CU, wherein the scan direction indication is coded with a single context.   
     
     
         32 . The method of  claim 31 , wherein a context value for encoding the scan direction indication for the CU is independent of a palette coding scan direction associated with another CU. 
     
     
         33 . The method of  claim 31 , wherein the CU is a first CU, and a context value for encoding the scan direction indication for the first CU is independent of a palette coding scan direction associated with a second CU neighboring the first CU. 
     
     
         34 . The method of  claim 31 , wherein the CU is a first CU, and the scan direction indication for the first CU is coded with a context that does not depend on a palette coding scan direction associated with a second CU that neighbors the first CU. 
     
     
         35 . The method of  claim 31 , wherein the scan direction indication for the CU is a palette transpose flag configured to indicate whether a horizontal traverse scan or a vertical traverse scan is applied for scanning palette indices of samples in the CU. 
     
     
         36 . The device for video encoding, comprising:
 a processor configured to:
 determine a palette coding scan direction for a coding unit (CU); and 
 encode a scan direction indication configured to indicate the determined palette coding scan direction associated with the CU, wherein the scan direction indication is coded with a single context. 
   
     
     
         37 . The device of  claim 36 , wherein a context value for encoding the scan direction indication for the CU is independent of a palette coding scan direction associated with another CU. 
     
     
         38 . The device of  claim 36 , wherein the CU is a first CU, and a context value for encoding the scan direction indication for the first CU is independent of a palette coding scan direction associated with a second CU neighboring the first CU. 
     
     
         39 . The device of  claim 36 , wherein the CU is a first CU, and the scan direction indication for the first CU is coded with a context that does not depend on a palette coding scan direction associated with a second CU that neighbors the first CU. 
     
     
         40 . The device of  claim 36 , wherein the scan direction indication for the CU is a palette transpose flag configured to indicate whether a horizontal traverse scan or a vertical traverse scan is applied for scanning palette indices of samples in the CU.