High pass filter in MATLAB

Hi,

I understand that high pass filter is essentially, orignal image - low pass filter.

I attempted the following but gotten a black screen. Anyone knows what when wrong? Thanks lots!

--CODE-

A=imread('image.jpg');

G=fspecial('gaussian', [50 50], 5); 

Ig=imfilter(A,G,'same'); 

JK=A-Ig; 

S=imshow(JK) >>> the output here is black image.

Answer 1

[Christian Lenz]

normalize image...

 A = double( imread('image.jpg'));
 A = A./max(max(max(A)));

keep the rest.

[Yvonne]

I add the 2 lines, the image is still black.

[Ryan]

S = imshow(JK,[])

[Christian Lenz]

It's not black when I do it... Tried another image?

[Christian Lenz]

Or play with your parameters (thresholding)

[Yvonne]

Thanks! I need to do mat2gray as well =)