A wavelet-based image compression system and method are presented. Compression
is accomplished by performing a wavelet transformation of an input digital image.
The resulting wavelet coefficients are compared to a threshold value. Coefficients
falling below the threshold are discarded. The remaining coefficients are quantized.
The quantized coefficients are then compressed using an entropy encoding technique,
such as arithmetic, run length, or Huffman encoding, or a combination of Huffman
and run length encoding. The wavelet transform can be an integer wavelet transform
derived using a lifting scheme or correction method, while the quantization scheme
can be sub-band oriented. Input color image pixels can be reduced using a color
table. In addition, color pixels can be transformed between color spaces prior
to wavelet transformation.
