Image coding apparatus, image coding method and computer readable medium storing program

摘要

An image coding apparatus includes: a transformation unit that transforms spatial domain image data having plural pixels, by a pixel block including plural pixels as a unit, into plural coefficient groups each including plural frequency domain coefficients; a grouping unit that classifies the plural coefficient groups into plural groups for classification of values in these coefficient groups; a quantization coefficient calculation unit that calculates a quantization coefficient used for quantizing plural coefficients included in the respective plural coefficient groups based on the number of coefficient groups classified in the plural groups and the values of the coefficient groups classified in the plural groups; a quantization unit that quantizes the respective plural coefficients included in the respective plural coefficient groups obtained by the transformation by using the calculated quantization coefficient; and a coding unit that encodes the plural coefficients included in the plural quantized coefficient groups to generate codes.