fn compare_to_truth<P, F>(input_file_name: &str, truth_file_name: &str, op: F)
where
    P: Pixel<Subpixel = u8> + PixelWithColorType,
    Image<P>: FromDynamic,
    F: Fn(&Image<P>) -> Image<P>,
{
    compare_to_truth_with_tolerance(input_file_name, truth_file_name, op, 0u8);
}
Loads an input image, applies a function to it and checks that the result matches a 'truth' image.
tests/regression.rs