Compression and decompression system with reversible wavelets and lossy reconstruction

An apparatus for performing reconstruction comprising:

• means for saving DS and DD coefficients effected by a boundary;
• means for reconstructing SD coefficients to be smooth across the boundary;
• means for applying a vertical inverse transform individually on each tile;
• means for reconstructing D coefficients to be smooth across the boundary;
• and
• means for applying a horizontal inverse transform individually on each tile.

A computer software product including a medium readable by a processor, the medium having stored thereon a sequence of instructions which, when executed by the processor, causes the processor, for each level, to:

• save DS and DD coefficients effected by a boundary,
• reconstruct SD coefficients to be smooth across the boundary,
• apply a vertical inverse transform individually on each tile,
• reconstruct D coefficients to be smooth across the boundary, and
• apply a horizontal inverse transform individually on each tile.

A method of performing an inverse transform comprising the steps of:

• a) performing an inverse vertical transform on SS and SD coefficients only;
• b) performing the inverse vertical transform on DS and DD coefficients on two current lines of coefficients using DS coefficients from two previous lines;
• c) performing an inverse horizontal transform for two vertically adjacent S and D coefficient pairs in said two current lines of coefficients;
• and
• d) repeating b) and c) for each pair of lines after the two current lines.

An apparatus for performing an inverse transform comprising:

• means for performing an inverse vertical transform on SS and SD coefficients only;
• means for performing the inverse vertical transform on DS and DD coefficients on two current lines of coefficients using DS coefficients from two previous lines;
• means for performing an inverse horizontal transform for two vertically adjacent S and D coefficient pairs in said two current lines of coefficients;
• and
• wherein the means for performing an inverse vertical transform on SS and SD coefficients, the means for performing the inverse vertical transform on DS and DD coefficients, and the means for performing an inverse horizontal transform perform their operations repeatedly for each pair of lines after the two current lines.

A computer software product including a medium readable by a processor, the medium having stored thereon a sequence of instructions which, when executed by the processor, causes the processor to:

• a) perform an inverse vertical transform on SS and SD coefficients only,
• b) perform the inverse vertical transform on DS and DD coefficients on two current lines of coefficients using DS coefficients from two previous lines,
• c) perform an inverse horizontal transform for two vertically adjacent S and D coefficient pairs in said two current lines of coefficients, and
• d) repeat b) and c) for each pair of lines after the two current lines.

A method of creating a preferred reconstruction comprising the steps of:

• a) for each SD coefficient, computing a preferred reconstruction and clipping the preferred reconstruction to be consistent with quantization;
• b) performing an inverse vertical transform on SS and SD coefficients only;
• c) for each DS and DD coefficient, computing a preferred reconstruction and clipping the preferred reconstruction to be consistent with quantization;
• d) performing the inverse vertical transform on DS and DD coefficients on two current lines of coefficients using DS coefficients from two previous lines;
• e) performing an inverse horizontal transform for two vertically adjacent S and D coefficient pairs in said two current lines of coefficients;
• and
• f) repeating d) and e) for each pair of lines after the two current lines.

An apparatus for creating a preferred reconstruction comprising:

• means for computing, for each SD coefficient, a preferred reconstruction and clipping the preferred reconstruction to be consistent with quantization;
• means for performing an inverse vertical transform on SS and SD coefficients only;
• means for computing, for each DS and DD coefficient, a preferred reconstruction and clipping the preferred reconstruction to be consistent with quantization;
• means for performing the inverse vertical transform on DS and DD coefficients on two current lines of coefficients using DS coefficients from two previous lines;
• means for performing an inverse horizontal transform for two vertically adjacent S and D coefficient pairs in said two current lines of coefficients;
• and
• wherein the means for performing the inverse vertical transform on DS and DD coefficients and the means for performing an inverse horizontal transform for two vertically adjacent S and D coefficient pairs operate repeatedly for each pair of lines after the two current lines.

A computer software product including a medium readable by a processor, the medium having stored thereon a sequence of instructions which, when executed by the processor, causes the processor to:

• a) for each SD coefficient, compute a preferred reconstruction and clipping the preferred reconstruction to be consistent with quantization,
• b) perform an inverse vertical transform on SS and SD coefficients only,
• c) for each DS and DD coefficient, compute a preferred reconstruction and clipping the preferred reconstruction to be consistent with quantization,
• d) perform the inverse vertical transform on DS and DD coefficients on two current lines of coefficients using DS coefficients from two previous lines,
• e) perform an inverse horizontal transform for two vertically adjacent S and D coefficient pairs in said two current lines of coefficients, and
• f) repeat d) and e) for each pair of lines after the two current lines.

A method for processing encoded data, said method comprising the steps of:

• receiving an indication of the amount of data used to encode importance levels over n tiles in the encoded data;
• determining a predetermined amount of the encoded data to decode;
• and
• decoding only the predetermined amount of the encoded data so that decoded data is obtained with the same fidelity over each tile.

An apparatus for processing encoded data, said apparatus comprising:

• means for receiving an indication of the amount of data used to encode importance levels over n tiles in the encoded data;
• means for determining a predetermined amount of the encoded data to decode;
• and
• means for decoding only the predetermined amount of the encoded data so that decoded data is obtained with the same fidelity over each tile.

A computer software product including a medium readable by a processor, the medium having stored thereon a sequence of instructions which, when executed by the processor, causes the processor to:

• receive an indication of the amount of data used to encode importance levels over n tiles in the encoded data;
• determine a predetermined amount of the encoded data to decode;
• and
• decode only the predetermined amount of the encoded data so that decoded data is obtained with the same fidelity over each tile.

A method of reconstructing comprising the steps of:

• determining a difference between a first coefficient and a second coefficient of predetermined number of coefficients where the first coefficient has a minimum value among the coefficients and the second coefficient has a maximum value among the coefficients;
• reconstructing to other than a step edge where the difference between the predetermined number of coefficients is less than a predetermined threshold value;
• reconstructing to a step edge where the difference between the predetermined number of coefficients is greater than a predetermined threshold value, wherein the step of reconstructing to a step edge comprises the steps of
• computing first and second partial reconstruction values based on a predetermined number of coefficient values to the right and to the left of a location of a potential step edge,
• computing a reconstruction value using one of the first and second partial reconstruction values based on whether one of the first and second partial reconstruction values is zero and whether signs of the first and second partial reconstruction values are the same.

A method of modeling binary data comprising the steps of:

• determining whether a first predetermined number of bits in a frequency band are the same;
• sending a first bit having a first state and a second bit to a coder if the predetermined number of bits in the frequency band are the same, where the second bit indicates whether the first predetermined number of bits are all 1 or all 0;
• sending the first bit having a second state different from the first state to the coder if the first predetermined number of bits in the frequency band are not the same;
• if the first predetermined number of bits in the frequency band are not the same, then determining whether a second predetermined number of bits are the same;
• sending a third bit indicating whether the second predetermined number of bits are the same;
• and
• sending a context for a target bit based on neighboring coefficients if the second predetermined number of bits are not the same.

A method for processing data comprising the steps of:

• determining whether to attempt to code a predetermined number of coefficients as a group;
• coding the predetermined number of coefficients individually using a first context model if not attempting to code the predetermined number of coefficients as a group;
• first coding the predetermined number of coefficients when the data is in a predetermined state and attempting to code the predetermined number of coefficients as a group is successful;
• and
• second coding each coefficient in the predetermined number of coefficients independently when the data is not in the predetermined state and attempting to code the predetermined number of coefficients as a group fails, wherein second coding uses a second context model different than the first context model.