pub fn adaptive_threshold(image: &GrayImage, block_radius: u32) -> GrayImageExpand description
Applies an adaptive threshold to an image.
This algorithm compares each pixel’s brightness with the average brightness of the pixels
in the (2 * block_radius + 1) square block centered on it. If the pixel is at least as bright
as the threshold then it will have a value of 255 in the output image, otherwise 0.