These functions perform one-dimensional reversible (_B53 modifier) and irreversible (_D97 modifier) wavelet transforms of image rows or columns for lossless and lossy compressions, respectively, in accordance with [ISO15444], Annex F, Discrete Wavelet Transformation of Tile-Components. The transformations are the lifting-based implementations of filtering by 5-3 reversible and 9-7 irreversible wavelet filters.
The filters have odd length: 5 (9) - for lowpass filters, and 3 (7) - for highpass filters.
There are two possible relative positions of lowpass and highpass filters allowed by the standard, as shown in the Figure “Sample Image Changed by the ippiResize Function”. The relative position is specified by the phase argument that has two possible values:
ippWTFilterFirstLow |
corresponds to positions a), |
ippWTFilterFirstHigh |
corresponds to positions b). |
The wavelet transform functions do not apply any fixed border extension (symmetrical, wraparound or other) to the source image ROI, instead they require valid and accessible border data outside of the source image ROI.
