Back to results
US RE43,649 E1Granted
Progressive block-based coding for image compression
AssigneeAyscough Visuals LLC
InventorDonald Martin Monro
Life of this patent
Estimating the term…
Abstract
A method of image compression includes significance switching of DCT coefficients in block-based embedded DCT procedures. Bitwise digitized DCT coefficients are passed through successive significance sweeps of the whole image from the most significant down to the least significant coefficient bit planes. With each new sweep, newly significant coefficients may appear within a block, and block-masking is used to transmit the addresses of those newly significant coefficients. An off-mask may also be used. The invention further relates to a hardware or software-based image encoder.
Claims22
A method of image compression comprising the steps of:
- (a) dividing an image to be compressed into a plurality of image blocks;
- (b) carrying out a two-dimensional block transform on each block to produce a corresponding plurality of coefficient blocks;
- (c) bitwise digitizing the coefficients within each coefficient block to define a plurality of bit planes for each coefficient block;
- (d) defining a group of one or more consecutive bit planes starting with the most significant bit plane;
- (e) selectively flagging those, by a coder device, coefficients which first become significant within the a group of one or more consecutive bit planes of corresponding coefficient blocks of image blocks resulting from a block transform, starting with the most significant bit plane;
- and
- (f) transmitting, by the coder device, information representative of the positions of the said flagged coefficients and transmitting the bits within the a group of the said flagged coefficients;
- and,
- (g) repeating steps (d) to (f) one or more times, with each new group starting with the most significant bit plane not previously dealt with and, at each repeated pass, also transmitting the bits within the current group of those coefficients which were previously flagged on an earlier pass.
6 more elements
A coder for encoding images device, comprising the steps of:
- (a) means for dividing an image to be compressed into a plurality of image blocks;
- (b) means for carrying out a two-dimensional block transform on each block to produce a corresponding plurality of coefficient blocks;
- (c) means for bitwise digitizing the coefficients within each coefficient block to define a plurality of bit planes for each coefficient block;
- (d) means for defining a group of one or more consecutive bit planes starting with the most significant bit plane;
- (e) means for a mechanism configured to selectively flagging those flag coefficients which first become significant within the a group of one or more consecutive bit planes of corresponding coefficient blocks of image blocks resulting from a block transform, starting with the most significant bit plane;
- and
- (f) means for a mechanism configured to transmitting transmit information representative of the positions of the said flagged coefficients and transmitting the bits within the a group of the said flagged coefficients;
- and,
- (g) means for repeating steps (d) to (f) one or more times, with each new group starting with the most significant bit plane not previously dealt with, and means for transmitting, at each repeated pass, the bits within the current group of those coefficients which were previously flagged on an earlier pass.
6 more elements
A video coder/decoder comprising:
- a coder and an associated decoder, wherein
- (1) the coder encoding images and comprising the steps of comprises:
- (a) means for dividing a mechanism configured to divide an image to be compressed into a plurality of image blocks;
- (b) means for a mechanism configured to carrying carry out a two-dimensional block transform on each block to produce a corresponding plurality of coefficient blocks;
- (c) means for a mechanism configured to bitwise digitizing the digitize coefficients with within each coefficient block to define a plurality of bit planes for each coefficient block;
- (d) means for defining a mechanism configured to define a group of one or more consecutive bit planes starting with the a most significant bit plane;
- (e) means for a mechanism configured to selectively flagging flag those coefficients which first become significant within the group;
- (f) means for a mechanism configured to transmitting transmit information representative of the positions of the said flagged coefficients and for transmitting the bits within the a group of the said flagged coefficients;
- and,
- (g) means for a mechanism configured to repeating steps (d) to (f) repeat operation of the mechanism configured to define a group and the mechanism configured to transmit information one or more times, with each new group starting with the a most significant bit plane not previously dealt with, and means for transmitting, at each repeated pass, the bits within the a current group of those coefficients which were previously flagged on an earlier pass, and
- (2) the decoder being arranged to maintain a running record, as transmission between the coder and the decoder proceeds, of the coefficients which are currently significant.
8 more elements
Dependencies are inferred from the claim text.