For illustrative purposes, the pseudo code of the picture header 300 is shown in FIG. 3 with darkened lines 311-313. Lines 311-313 allows additional chroma QP offset values and defines chroma quantization groups for chroma QP offsets in the picture 102. Specifically, the parameter “additional_chroma_qp_offset” in line 311 informs the decoder that there will be additional chroma QP offset specification in the bitstream. When this variable is not set for a particular picture, the bitstream would not include bits for specifying the additional chroma QP offset for the picture in order to avoid wasting bits.

The parameter “chroma_qp_offset_max_depth” in the line 313 defines the level (and hence the size or the hierarchical depth) of the chroma QG. This parameter can be set to be equal to the size of the entire coding tree unit (CTU) or down to the size of the smallest coding unit possible in the bitstream. Some embodiments allow the specification and signaling of additional chroma QP offsets to occur at any desirable level (e.g., at the CTU level, chroma defined quantization group level, coding unit level, transform unit level, etc.) In some embodiments, instead of defining quantization groups specifically for chroma QP offsets, the bitstream uses the parameter “diff_cu_qp_delta_depth”, which also defines the quantization groups for luma QPs. In some embodiments, if the parameter for defining a quantization group is not available, then the entire picture is assigned the same QP for luma and no QP adaptations for luma are permitted.