Image decoding method, image coding method, image decoding apparatus, image coding apparatus, program, and integrated circuit

A decoding apparatus for decoding a coded stream to generate a picture, the picture including a plurality of units, each of the units including a plurality of blocks, the decoding apparatus comprising:

• a processor;
• and
• a non-transitory memory having stored thereon executable instructions, which when executed, cause the processor to perform:
• determining, using first information in a picture header of a picture, whether or not a first quantization parameter to be used for decoding a first block is provided for a unit, the picture including the unit, the unit including the first block;
• and
• decoding the first block,
• wherein, when the first quantization parameter is determined to be provided, (i) the decoding includes deriving a value for dequantization by using the first quantization parameter and (ii) the first quantization parameter is used for other blocks included in the unit, and
• wherein, when the first quantization parameter is determined not to be provided, the decoding includes deriving a value for dequantization by not using the first quantization parameter and by using a second quantization parameter which is provided for the first block.

A coding method for coding a picture to generate a coded stream, the picture including a plurality of units, each of the units including a plurality of blocks, the coding method comprising:

• determining, using first information in a picture header of a picture, whether or not a first quantization parameter to be used for coding a first block is provided for a unit, the picture including the unit, the unit including the first block;
• and
• coding the first block,
• wherein, when the first quantization parameter is determined to be provided, (i) the coding includes deriving a value for dequantization by using the first quantization parameter and (ii) the first quantization parameter is used for other blocks included in the unit, and
• wherein, when the first quantization parameter is determined not to be provided, the coding includes deriving a value for dequantization by not using the first quantization parameter and by using a second quantization parameter which is provided for the first block.

A coding apparatus for coding a picture to generate a coded stream, the picture including a plurality of units, each of the units including a plurality of blocks, the coding apparatus comprising:

• a processor;
• and
• a non-transitory memory having stored thereon executable instructions, which when executed, cause the processor to perform:
• determining, using first information in a picture header of a picture, whether or not a first quantization parameter to be used for coding a first block is provided for a unit, the picture including the unit, the unit including the first block;
• and
• coding the first block,
• wherein, when the first quantization parameter is determined to be provided, (i) the coding includes deriving a value for dequantization by using the first quantization parameter and (ii) the first quantization parameter is used for other blocks included in the unit, and
• wherein, when the first quantization parameter is determined not to be provided, the coding includes deriving a value for dequantization by not using the first quantization parameter and by using a second quantization parameter which is provided for the first block.