How did you convert the image to double? If you did something like
A = imread('mypicture.jpg');
A = double(A);
then the image will be just be cast without being normalized. You'd want to use im2double() which does both.
Otherwise, if you did some operations on the image which pushed all the values outside the range [0 1], then you'll have to normalize it.
The image processing tools expect images to be scaled appropriately according to their class. For uint8, that'd be [0 255]. For floating point classes, it's [0 1]. If you have a [0 255] image cast as double and try to view it with imshow(), almost all the pixels will be rendered as white. When you use
imshow(A,[])
it handles the data ranging internally.
Long story short, yes it handles double images. Just make sure your images are scaled according to their class (normalized in this case).
