Method and apparatus for performing compression of a color image

A method for compressing a color image comprising color image samples Sij arranged in a reference grid according to a sampling pattern, the reference grid comprising a number of lines and columns, the index i starting at 0 and increasing with the lines, and the index j starting at 0 and increasing with the columns, into a packed data set, the method comprising:

• a) performing a decorrelative transform, wherein for each position (i,j) of the reference grid, a component sample Ckij is determined, k being a component index depending on the sampling pattern, Ckij being a linear combination of the image samples Si′j′ at positions (i′,j′), wherein i′ is comprised between i−4 and i+4, and j′ is comprised between j−4 and j+4, producing component images C0, C1, and C2, and, depending on the sampling pattern, an optional component image C3;
• b) repeating for each component Ck:
• Nlky being a number of vertical DWT decompositions to be applied to component Ck, being an integer >=0,
• Nlkx being a number of horizontal DWT decompositions to be applied to component Ck, being an integer >=Nlky,
• considering the component Ck as an auxiliary subband;
• if Nlky >0, repeat, for n=0 to Nlky−1,
• performing on said auxiliary subband a vertical DWT decomposition, by performing a lifting scheme with (5,3) filter-bank on the columns of said auxiliary subband, the resulting even numbered samples being a LLn subband, the resulting odd numbered samples being a LHn subband, keeping for each resulting sample a reference to the position (i,j) in the reference grid wherefrom they are determined;
• performing on said LLn subband a horizontal DWT decomposition, by performing a lifting scheme with (5,3) filter-bank on the lines of said subband, the resulting even numbered samples being a LLn subband, the resulting odd numbered samples being a HLn subband, keeping for each resulting sample a reference to the position (i,j) in the reference grid wherefrom they are determined;
• performing on said LHn subband a horizontal DWT decomposition, by performing a lifting scheme with (5,3) filter-bank on the lines of said subband, the resulting even numbered samples being a LHn subband, the resulting odd numbered samples being a HHn subband, keeping in for each resulting sample a reference to the position (i,j) in the reference grid wherefrom they are determined;
• considering subband LLn as an auxiliary subband, if Nlkx > Nlky, repeat, for n=Nlky to Nlkx−1,
• performing on said LLn−1 subband a horizontal DWT decomposition, by performing a lifting scheme with (5,3) filter-bank on the lines of said subband, the resulting even numbered samples being a LLn subband, the resulting odd numbered samples being a HLn subband, keeping for each resulting sample a reference to the position (i,j) in the reference grid, wherefrom they are determined;
• and
• considering subband LLn as an auxiliary subband;
• and
• c) for each consecutive line of the reference grid,
• for each component Ck,
• grouping all samples of said component Ck in said line in one or more packets;
• and
• appending the one or more packets to the packed data set, wherein the packed data set comprises:
• a sequence of the packets, wherein each of the packets contains only data from a single component image, wherein each of the packets contains only data from a single line of a component image, and wherein all of the packets containing data from a given line of a component image are located in the packed data set before any packet containing data from a subsequent line of any component image.