Can someone please confirm if this is indeed the correct way to compute DWT:
load image
load Haar wavelet
for i = 1: Level
periodize edges of image
convolve image with Low pass Haar wavelet filter and store result in G
convolve image with Low pass Haar wavelet filter and store result in H
convolve G with low pass Haar to calculate approximation co-eff
convolve G with high pass Haar to calculate horizontal co-eff
convolve H with low pass Haar to calculate vertical co-eff
convolve H with high pass Haar to calculate diagonal co-eff
i = i + 1
downsample approximation by 2
end
In case of SWT, instead of down-sampling the approximation, Haar filter co-efficients are up-sampled twice at each level and the same process is repeated. Am I correct here?