Abstract: An image compression apparatus is provided, which includes a wavelet transformer, a quantizer, a comparator, a subtracter, a low data compressor and a high data compressor. The comparator compares the first quantization coefficients of the first quantization data, to output the maximum quantization coefficient. The subtracter subtracts the minimum quantization coefficient from the maximum quantization coefficient, to output a subtraction constant. The low data compressor subtracts the subtraction constant from the first quantization coefficients, to output low compression data obtained by compressing the first quantization data.

Abstract: An image compression method using a wavelet transform is provided. The image compression method includes a first wavelet transform process, a storage process, a second wavelet transform process, a quantization process and an entropy encoding process. The first wavelet transform process wavelet-transforms image data as many as a reference wavelet transform number of times in any one direction of a row-direction or a column-direction, to thereby output first low-frequency wavelet transform data and first high-frequency wavelet transform data. The second wavelet transform process wavelet-transforms the first low-frequency wavelet transform data and the last first high-frequency wavelet transform data which are stored in a memory as many as the reference wavelet transform number of times in a direction differing from that performed in the first wavelet transform process, to thereby output second low-frequency wavelet transform data and second high-frequency wavelet transform data.

Abstract: An image compression apparatus is provided, which includes a wavelet transformer, a quantizer, a comparator, a subtracter, a low data compressor and a high data compressor. The comparator compares the first quantization coefficients of the first quantization data, to output the maximum quantization coefficient. The subtracter subtracts the minimum quantization coefficient from the maximum quantization coefficient, to output a subtraction constant. The low data compressor subtracts the subtraction constant from the first quantization coefficients, to output low compression data obtained by compressing the first quantization data.