Linear Time Complexity of 2D Wavelet Transform
Let n = number of pixels and let b be the number of coefficients in the filters.
One level of transform takes time
k levels of transform takes time proportional to
- bn + bn/4 + ... + bn/4k-1 < (4/3)bn.
The wavelet transform is linear time when the filters have constant size.
- The point of wavelets is to use constant size filters unlike many other transforms.