Decoding device, distribution estimation method, decoding method and programs thereof

A decoding method comprising:

• approximating distribution data indicating a distribution of signal of other component by a function regarding the component to estimate a distribution of a target component;
• calculating distribution data of the target component by the function based on the approximated process;
• calculating a inverse quantized value by the calculated distribution data of the target component;
• and
• generating decoded data by the calculated inverse quantized value.

A decoding device comprising:

• a first distribution generation unit that generates distribution data indicating a distribution of data before quantization for any of component based on a frequency distribution of quantization index;
• a second distribution generation unit that generates distribution data of other component based on the distribution data generated by the first distribution generation unit;
• and
• a inverse quantized value generation unit that generates a inverse quantized value corresponding to a quantization index based on the distribution data generated by the first distribution generation unit or the distribution data generated by the second distribution generation unit.