the effect of PSF in x-ray image

hi am trying to find the effect of the PSF on x-ray image , i generate the psf using a for loop then use convolution with the image , after that taking fft for both PSF and image seeing the spectrum ... but after conv function and ifft it give black image why?

clc
clear all
close all
im=imread('xray2.jpg');
[m,n]=size(im);
PSF=zeros(n,m);
Y=size(PSF,1);
X=size(PSF,2);
s_x=1;
s_y=5;

for x=1:X

   for y=1:Y

PSF(y,x) = exp(-((x-X).^2/(2*s_x^2) + (y-Y).^2)/(2*s_y^2));

    end
end

%Display PSF

figure(1)

imshow(PSF)

title('PSF')

colormap gray

figure(2)

imshow(im)

colormap cool

title('x-ray image for hand') %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

im_conv=convn(im,PSF,'full');

figure(3)

imshow(im_conv)

title('x-ray image convolved with PSF') %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

psf_fft=fftshift(fft2(PSF));

im3=fft2(PSF);

fft_res=psf_fft.*im3;

figure(4)

imshow(fft_res)

title('the ruselt of FFT ') %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

im4=ifft(fft_res);

figure(5)

imshow(im4)

title('IFFT')

Answer 1

[Image Analyst]

im needs to be cast to double, and you need to use [] in imshow(fft_res, []). And you can also use conv2() instead of convn().

[Hasan alomari]

it dose't work and the psf generation for loop it give me the PSF in the corner of the image

[Image Analyst]

Attach your script and image file.

[Hasan alomari]

It's attached below.

[Image Analyst]

im is a color image and thus n is not right. See Steve's blog : http://blogs.mathworks.com/steve/2011/03/22/too-much-information-about-the-size-function/ Plus your PSF is ridiculously large - it doesn't need to be as big as the image.

[Image Analyst]

See code:

clc
clear all
close all
fontSize = 20;
grayImage=imread('d:\temporary stuff\xray2.jpg');
[rows,columns, numberOfColorChannels]=size(grayImage);
if numberOfColorChannels > 1
  % Convert color image to gra by taking green channel.
  grayImage = grayImage(:,:,2);
end
subplot(3, 3, 1);
imshow(grayImage);
axis on;
colormap cool
title('x-ray image for hand', 'FontSize', fontSize);
% Enlarge figure to full screen.
set(gcf, 'Units', 'Normalized', 'OuterPosition', [0 0 1 1]);
% Give a name to the title bar.
set(gcf, 'Name', 'Demo by ImageAnalyst', 'NumberTitle', 'Off') 

% Compute a PSF.
psfWidth = 15;
PSF = fspecial('gaussian', psfWidth, 5);
% Display PSF
subplot(3, 3, 2);
imshow(PSF, [])
title('PSF', 'FontSize', fontSize);
axis on;
colormap bone

% Blur the image
im_conv = conv2(double(grayImage),PSF,'full');
subplot(3, 3, 3);
imshow(im_conv, [])
axis on;
title('x-ray image convolved with PSF', 'FontSize', fontSize);

% Calculate FFT of the image and display it.
image_fft = fft2(grayImage);
subplot(3, 3, 4);
niceImageToDisplay = log(fftshift(real(image_fft)));
imshow(niceImageToDisplay, [])
axis on;
title('FFT of hand image.', 'FontSize', fontSize);

% Calculate FFT of the PSF and display it.
psf_fft = fft2(PSF);
subplot(3, 3, 5);
niceImageToDisplay = log(fftshift(real(psf_fft)));
imshow(niceImageToDisplay, [])
axis on;
title('FFT of PSF', 'FontSize', fontSize);

% Calculate the FFT of the blurred image and display it.
blurryImage_fft = fft2(im_conv);
subplot(3, 3, 6);
niceImageToDisplay = log(fftshift(real(blurryImage_fft)));
imshow(niceImageToDisplay, [])
axis on;
title('FFT of blurred hand image.', 'FontSize', fontSize);

% Multiply the FFT of the PSF by the FFT of the image.
p = ceil([rows-psfWidth, columns - psfWidth]/2)
fftSameSize = padarray(fftshift(psf_fft),  p);
% Adjust size slightly so we can multiply them.
fftSameSize = imresize(fftSameSize, [rows, columns]);
fftProduct = fftSameSize .* fftshift(image_fft);
% Display it.
subplot(3, 3, 7);
niceImageToDisplay = log(real(fftProduct));
imshow(niceImageToDisplay, [])
axis on;
title('Product of the two FFTs.', 'FontSize', fontSize);

[Hasan alomari]

it works also with the PSF i generate thank you for your help :)