Patent ID: 8433151

Claim:
An image coding apparatus comprising: a processor; and a memory storing instructions, which when executed cause the processor to act as: a transformation unit that is configured to transform spatial domain image data having a plurality of pixels, by a pixel block including a plurality of pixels as a unit, into a plurality of coefficient groups each including a plurality of frequency domain coefficients; a grouping unit that is configured to classify the plurality of coefficient groups into a plurality of groups for classification of values in these coefficient groups; a quantization coefficient calculation unit that is configured to calculate a quantization coefficient used for quantizing a plurality of coefficients included in the respective plurality of coefficient groups based on the number of coefficient groups classified in the plurality of groups and the values of the coefficient groups classified in the plurality of groups; a quantization unit that is configured configured to quantize the respective plurality of coefficients included in the respective plurality of coefficient groups obtained by the transformation by using the calculated quantization coefficient; and a coding unit that is configured to encode the plurality of coefficients included in the plurality of quantized coefficient groups to generate codes.