How to fix the Background Image scale in a overlay image

Here is referece code http://stackoverflow.com/questions/6524886/image-overlay-with-matrix

%# some image I = im2double( imread('peppers.png') );

%# I create here a random mask (gaussian centered in middle of image) [r,c,~] = size(I); [X Y] = meshgrid(1:r,1:c); Z = mvnpdf([X(:) Y(:)], [r c]./2, diag(15.*[r c])); Z = (Z-min(Z(:)))./range(Z(:)); Z = reshape(Z',[c r])';

%# show image and mask separately subplot(121), imshow(I) subplot(122), imshow(Z)

%# show overlayed images figure, imshow(I), hold on hImg = imshow(Z); set(hImg, 'AlphaData', 0.6);

The result image shows that the background rgb image is different from the original image Can you fix the original scale? I don't want the black area to have any effect.

[Rik]

Select your code and click on the {}Code button.

Have you tried the suggestion on StackOverflow of using h=imshow(I); set(h, 'AlphaData',Z)?