Encoder, decoder, methods and computer programs for an improved lossless compression

A method for encoding a picture into a data stream, the method comprising:

• signaling a plurality of coding parameters in the data stream which relate to a predetermined portion of the picture and control a prediction residual transform mode and a quantization accuracy with respect to the predetermined portion;
• checking whether the plurality of coding parameters are indicative of a coding parameter setting corresponding to a lossless prediction residual coding;
• and
• responsive to the plurality of coding parameters being indicative of the coding parameter setting corresponding to the lossless prediction residual coding, setting one or more predetermined coding options relating to one or more tools of the encoder for processing a prediction residual corrected predictive reconstruction with respect to the predetermined portion so that the one or more tools are disabled with respect to the predetermined portion.

A non-transitory digital storage medium having a computer program stored thereon to perform a method for encoding a picture into a data stream when the computer program is run on a computer, the method comprising:

• signaling a plurality of coding parameters in the data stream which relate to a predetermined portion of the picture and control a prediction residual transform mode and a quantization accuracy with respect to the predetermined portion;
• checking whether the plurality of coding parameters are indicative of a coding parameter setting corresponding to a lossless prediction residual coding;
• and
• responsive to the plurality of coding parameters being indicative of the coding parameter setting corresponding to the lossless prediction residual coding, setting one or more predetermined coding options relating to one or more tools of the encoder for processing a prediction residual corrected predictive reconstruction with respect to the predetermined portion so that the one or more tools are disabled with respect to the predetermined portion.