a coding part that performs coding on image data based on a result or decomposing the image data into bit planes block by block;

a quantization part that reduces values of image data of a predetermined block to be compressed at an increased rate, the quantization part being provided at an earlier stage than the coding part; and

a transform part configured to perform a discrete wavelet transform to said image data to obtain wavelet coefficients including first blocks of higher-frequency components and second blocks of lower-frequency components,

wherein said quantization part includes a multiplier part configured to multiply a wavelet coefficient by a scaling factor,

wherein said multiplier part multiplies wavelet coefficients in said second blocks of lower-frequency components by a second scaling factor, and multiplies wavelet coefficients in the blocks of higher-frequency components by a first scaling factor that is lower than said second scaling factor applied to wavelet coefficients in said second blocks of lower-frequency components, and

wherein the quantization part further comprises:

a counter configured to receive said wavelet coefficients and output a count value;

a first comparator configured to receive said count value and a first reference value and output a first comparator signal;

a second comparator configured to receive said count value and a second reference value and output a second comparator signal; and

a selector configured to receive the first comparator signal and the second comparator signal, and outputs a scaling factor to said multiplier part in accordance with the first comparator signal and the second comparator signal.