FIG. 4 illustrates an example coding tree unit 400 that can be in a quantization group. The coding tree unit 400 is described by pseudo code modified from the H.265 pseudo code in order to accommodate additional chroma QP offsets. The coding tree unit 400 is in the quantization group 122, which is in the slice 112 of the picture 102.

The pseudo code for the coding tree unit 400 is illustrated with darkened lines 411-413, which are added for the purpose of determining whether the coding tree unit is part of a QG. Specifically, at line 411, the parameter “additional_chroma_qp_offset” (e.g., from the picture header 300) is used to indicate whether additional chroma information is allowed. The parameter “chroma_qp_offset_max_depth” is compared against a variable “l(fā)og 2CbSize” for determining whether the coding tree unit 400 is in a quantization group (such as the quantization group 122). If so, the pseudo code sets the variable “1sCrCuQpOffsetCoded” to 0 at line 412. For some embodiments, this also initializes the starting point of the chroma quantization group.

FIG. 5 illustrates the specification of additional chroma QP offsets within the QG 122. As discussed above by reference by FIGS. 3 and 4, the QG 122 has been defined by the picture header 300 to include the coding tree unit 400. The additional chroma QP offsets are specified within a transform unit 500 of the coding tree unit 400. The transform unit 500 is described by pseudo code modified from the H.265 pseudo code in order to accommodate additional chroma QP offsets.