Visually progressive ordering of compressed subband bit-planes and rate-control based on this ordering

A method of rate-control for one or more images comprising the steps of:

• a) encoding the images in a visually progressive manner to form a compressed bit-stream for each image;
• b) generating a table of visual significance values and corresponding file sizes for possible truncation points of the compressed bit-stream for each image;
• c) initializing a current truncation point for each image;
• d) truncating the compressed bit-stream for each image to the corresponding current truncation point;
• e) calculating a total compressed file size for the truncated compressed bit-streams;
• f) comparing the total compressed file size with a pre-determined bit-budget;
• g) updating the current truncation point to the next possible truncation point for the image having the lowest visual significance value at the next possible truncation point;
• and
• h) repeating steps d through g until the total compressed file size is equal to or less than the bit-budget.

A computer program product for encoding a digital image in a visually progressive manner comprising:

• a computer readable storage medium having a computer program stored thereon for performing the steps of:
• i) inputting the digital image;
• j) decomposing the digital image into two or more subbands;
• k) quantizing the subbands of the decomposed digital image to create quantized output values for each subband, wherein each subband is quantized with a specific quantizer step size;
• l) forming bit-planes from the quantized output values of each subband and calculating an effective quantizer step size for each bit-plane;
• m) computing a visual significance value for each bit-plane from the effective quantizer step size associated with that bit plane;
• n) ordering the bit-planes in decreasing order of the corresponding visual significance value;
• o) entropy coding the ordered bit-planes to produce a compressed bit-stream;
• and
• p) combining the compressed bit-stream with bit-plane ordering information to produce an encoded representation of the digital image.

A computer program product for rate-control for one or more images comprising:

• a computer readable storage medium having a computer program stored thereon for performing the steps of:
• a) encoding the images in a visually progressive manner to form a compressed bit-stream for each image;
• b) generating a table of visual significance values and corresponding file sizes for possible truncation points of the compressed bit-stream for each image;
• c) initializing a current truncation point for each image;
• d) truncating the compressed bit-stream for each image to the corresponding current truncation point;
• e) calculating a total compressed file size for the truncated compressed bit-streams;
• f) comparing the total compressed file size with a pre-determined bit-budget;
• g) updating the current truncation point to the next possible truncation point for the image having the lowest visual significance value at the next possible truncation point;
• and
• h) repeating steps d through g until the total compressed file size is equal to or less than the bit-budget.