Wavelet filtering

Apparatus for wavelet filtering a digital image, the digital image comprising a plurality of pixels arranged in one or more bands of pixels, the apparatus comprising:

• means for retrieving, for each one of said one or more bands of pixels, a plurality of previous partial results from a first or second storage;
• means for inputting, for each one of said one or more bands of pixels, a current group of adjacent said pixels;
• means for computing coefficients, for each one of said one or more bands of pixels, utilising said current group of adjacent pixels and said plurality of previous partial results;
• means for outputting, for each one of said one or more bands of pixels, said coefficients;
• and
• means for storing a plurality of current partial results in said first storage if said current group is not the last group in the band, in said second storage if said group is the last group in the band.

A computer readable medium comprising a computer program for wavelet filtering a digital image, the digital image comprising a plurality of pixels arranged in one or more bands of pixels, the computer program comprising:

• code for retrieving, for each one of said one or more bands of pixels, a plurality of previous partial results from a first or second storage;
• code for inputting, for each one of said one or more bands of pixels, a current group of adjacent said pixels;
• code for computing coefficients, for each one of said one or more bands of pixels, utilising said current group of adjacent pixels and said plurality of previous partial results;
• code for outputting, for each one of said one or more bands of pixels, said coefficients;
• and
• code for storing a plurality of current partial results in said first storage if said current group is not the last group in the band, in said second storage if said group is the last group in the band.

A wavelet filter for wavelet filtering a digital image, the digital image comprising a plurality of pixels arranged in one or more bands of pixels, the filter comprising:

• a first storage for storing a plurality of previous partial results;
• a second storage for storing a plurality of previous partial results;
• a controller for selecting the plurality of previous partial results from said first or second storage;
• a pixel input mechanism for inputting a current group of adjacent said pixels;
• a lifting lattice of multiplier and adder units for computing coefficients utilising said current group of adjacent pixels and said selected plurality of previous partial results;
• output means for outputting said coefficients;
• and
• a controller for storing a plurality of current partial results in said first storage if said current group is not the last group in the band, in said second storage if said group is the last group in the band.