I am using
ImageTransformation with a slow function. Is there a way to get
ImageTransformation to compute the function at only a few pixels, and then interpolate the function values for pixels in between?
For example, if $f((0,0))=(1,0)$, and $f((0,0.1))=(.9,.9)$, then it would assign the pixel at $(0,0.05)$ to the pixel at $(.95,.95)$.
Note that it should using every pixel of the input image (if warranted), it just shouldn't calculate the function for each pixel of the output image.