https://au.mathworks.com/help/images/ref/imgradient.html#bthgcil-method
imgradient does not normalize the gradient output. If the range of the gradient output image has to match the range of the input image, consider normalizing the gradient image, depending on the method argument used. For example, with a Sobel kernel, the normalization factor is 1/8, for Prewitt, it is 1/6, and for Roberts it is 1/2.
I'm confused with the last sentence. So excatly how to calculate the normalised gradient image with a sobel kernel for example?
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