The feature transform is a bit like the distance transform, but instead of storing the distance of each pixel from the nearest background pixel, it stores to co-ordinates of the nearest background pixel.
/** feature transform - like distance transform except gets the co-ordinates of the nearest background pixel Returns: feature transfrom [2][height][width] with rows in the first half of the buffer and columns in the second. */ int *featuretransform(unsigned char *binary, int width, int height)