Appendix E: Introduction to wavelet theory
-
PDF
75.548828125Kb
At first sight, wavelet transformation seems to combine several advantages of sub-band coding and conventional FFT or DCT while being computationally more efficient. The continuous nature of the transform, as opposed to DCT blocks, helps to avoid artefacts, and it appears to be better suited to the spatial de-correlation of texture in images. In the form of quadrature mirror filters (QMFs), a special case of wavelet filters has been known for some time. Wavelet theory generalises the principle of QMFs and provides a broader mathematical basis.