Fwht
Fast Walsh Hadamard Transform in C
Install / Use
/learn @bvssvni/FwhtREADME
FWHT - Fast Walsh Hadamard Transform in C BSD license. by Sven Nilsen, 2012 http://www.cutoutpro.com
Version: 0.000 in angular degrees version notation http://isprogrammingeasy.blogspot.no/2012/08/angular-degrees-versioning-notation.html
This implementation was made without looking at other FWHT algorithms, so I release under its own license.
// Compile unit tests with GCC.
gcc -o fwht-test fwht-test.c -Wall
// Run code.
./fwht-test
Fast Walsh Hadamard Transform
The input souce has to be in size 2^n.
Example use: You have two similar images where the camera is moved or rotated slightly and you want to find the transformation of the camera movement. You then take two 4x4 pieces of each image and transform each color channel with FWHT and then take the differences, sum them and you will have a number that tells you how similar the two pieces are.
When you apply a FWHT twice, you get the same as before, only multiplied with a factor of the size of the data.
