Imsubtract Returns Black Image

Hi, I am trying to retrieve the Laplacian pyramid for a given image. Here is a snippet from my code for the n=1 case:

inp = im2double(imread('gray.jpg'));

g = fspecial('gaussian',[5,5], 1.6);

blur = imfilter(inp, g, 'conv');
diff = imsubtract(inp , blur);

figure;
subplot(121);
imshow(blur)
subplot(122);
imshow(diff)

'blur' returns the correct gaussian-filtered image. However, it always returns a black image for the image 'diff'.

I have searched related questions and imsubtract guides, and I have asserted that all of my images have non-zero data in them, and that I am subtracting two images of the same type (double). I am at a loss for how to solve this problem. Any help is greatly appreciated.

Answer 1

[Isaiah Egan]

The solution: normalize the final image for display with

imshow(mat2gray(diff))

Answer 2

[Image Analyst]

Always use [] when using imshow() with floating point variables:

imshow(diffImage, []);

By the way, DON'T USE diff as a variable name since it's a built in function.