Inverse DWT method and apparatus
AssigneeCanon Kabushiki Kaisha
InventorTimothy John Lindquist
Life of this patent
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Abstract
A method for performing an Inverse Discrete Wavelet Transform is disclosed. The method comprises inverse transforming, using filters (706–710) having specified filter widths, data from associated sub-bands in a first sub-band level, to form processed data in a corresponding sub-band in the second sub-band level. The method further inverse transforms, in a pipeline fashion, using second filters (712–716) having the same corresponding associated filter widths, the processed data in conjunction with corresponding data from associated sub-bands in the second sub-band level.
Claims18
A method for performing an Inverse Discrete Wavelet Transform (IDWT) comprising, for a first sub-band level and a second sub-band level in an N level Discrete Wavelet Transform, the steps of:
- (i) processing, as soon as a first computation block is filled with sets of data points from corresponding sub-bands of the first sub-band level, those sets of data points from corresponding sub-bands of the first sub-band level, to form a set of processed data points in a sub-band of the second sub-band level;
- and
- (ii) processing, as soon as a second computation block is filled with the set of processed data points in the sub-band of the second sub-band level in conjunction with at least one set of data points from a corresponding at least one sub-band of the second sub-band level, that set of processed data points in the sub-band of the second sub-band level in conjunction with the at least one set of data points from said corresponding at least one sub-band of the second sub-band level, to form a set of processed data points in a sub-band of a subsequent sub-band level,
- wherein each set of data points is smaller than the number of data points in a corresponding sub-band level.
A method for performing an Inverse Discrete Wavelet Transform IDWT in relation to a 2-dimensional N level Discrete Wavelet Transform, said method comprising the steps of:
- (i) processing, as soon as a first computation block is filled with sets of M×M data points from corresponding sub-bands of a first sub-band level, those sets of M×M data points from corresponding sub-bands of a first sub-band level, to form a set of M×M processed data points in a sub-band of a second sub-band level;
- and
- (ii) processing, as soon as a second computation block is filled with the set of M×M processed data points in the sub-band of the second sub-band level in conjunction with sets of M×M data points from corresponding sub-bands of the second sub-band level, the set of M×M processed data points in the sub-band of the second sub-band level in conjunction with sets of M×M data points from corresponding sub-bands of the second sub-band level to form a set of M×M processed data points in a sub-band of a subsequent sub-band level,
- wherein each said set of M×M data points is smaller than the number of data points in a corresponding sub-band level.
An apparatus for performing an Inverse Discrete Wavelet Transform IDWT comprising, for a first sub-band level and a second sub-band level in an N level Discrete Wavelet Transform:
- (i) means for processing, as soon as a first computation block is filled with sets of data points from corresponding sub-bands of the first sub-band level, those sets of data points from corresponding sub-bands of the first sub-band level, to form a set of processed data points in a sub-band of the second sub-band level;
- and
- (ii) means for processing, as soon as second computational block is filled with the set of processed data points in the sub-band of the second sub-band level in conjunction with at least one set of data points from a corresponding at least one sub-band of the second sub-band level, the set of processed data points in the sub-band of the second sub-band level in conjunction with at least one set of data points from a corresponding at least one sub-band of the second sub-band level, to form a set of processed data points in a sub-band of a subsequent sub-band level,
- wherein each said set of data points is smaller than the number of data points in a corresponding sub-band level.
An apparatus for performing an Inverse Discrete Wavelet Transform IDWT in relation to a 2-dimensional N level Discrete Wavelet Transform, said apparatus comprising:
- (i) means for processing, as soon as a first computational block is filled with sets of M×M data points from corresponding sub-bands of a first sub-band level, those sets of M×M data points from corresponding sub-bands of a first sub-band level, to form a set of M×M processed data points in a sub-band of a second sub-band level;
- and
- (ii) means for processing, as soon as a second computational block is filled with the set of M×M processed data points in the sub-band of the second sub-band level in conjunction with sets of M×M data points from corresponding sub-bands of the second sub-band level, the set of M×M processed data points in the sub-band of the second sub-band level in conjunction with sets of M×M data points from corresponding sub-bands of the second sub-band level, to form a set of M×M processed data points in a sub-band of a subsequent sub-band level,
- wherein each said set of M×M data points is smaller than the number of data points in a corresponding sub-band level.
A computer readable memory medium storing a program for performing an Inverse Discrete Wavelet Transform IDWT, said program comprising in relation to a first sub-band level and an N level Discrete Wavelet Transform:
- (i) code for processing, as soon as a first computational block is filled with sets of data points from corresponding sub-bands of the first sub-band level, those sets of data points from corresponding sub-bands of the first sub-band level, to form a set of processed data points in a sub-band of the second sub-band level;
- and
- (ii) code for processing, as soon as a second computational block is filled with the set of processed data points in the sub-band of the second sub-band level in conjunction with at least one set of data points from a corresponding at least one sub-band of the second sub-band level, the set of processed data points in the sub-band of the second sub-band level in conjunction with at least one set of data points from a corresponding at least one sub-band of the second band level, to form a set of processed data points in a sub-band of a subsequent sub-band level,
- wherein each said set of data points is smaller than the number of data points in a corresponding sub-band level.
A computer readable memory medium storing a program for performing an Inverse Discrete Wavelet Transform IDWT in relation to a 2-dimensional N level Discrete Wavelet Transform, said program comprising:
- (i) code for processing, as soon as first computational block is filled with sets of M×M data points from corresponding sub-bands of a first sub-band level, those sets of M×M data points from corresponding sub-bands of a first sub-band level, to form a set of M×M processed data points in a sub-band of a second sub-band level;
- and
- (ii) code for processing, as soon as a second computational block is filled with the set of M×M processed data points in the sub-band of the second sub-band level in conjunction with sets of M×M data points from corresponding sub-bands of the second sub-band level, the set of M×M processed data points in the sub-band of the second sub-band level in conjunction with sets of M×M data points from corresponding sub-bands of the second sub-band level, to form a set of M×M processed data points in a sub-band of a subsequent sub-band level,
- wherein each said set of M×M data point is smaller than the number of data points in a corresponding sub-band level.
Dependencies are inferred from the claim text.