Saving filtered image

I have tested some code that applies homomorphic filtering to an image in the logarithmic space:

%%%%%log of image
im_l=log(1+im);
%%%%%DFT of logged image
im_f=fft2(im_l);
%%%%%Filter Applying DFT image
im_nf=H.*im_f;
%%%%Inverse DFT of filtered image
im_n=abs(ifft2(im_nf));
%%%%%Inverse log 
im_e=exp(im_n);

When this process is complete, the image can be displayed using imshow(im_e,[]), but since im_e is of type double I cannot save it as per what is seen from the imshow statement...

Does anyone know how to solve this problem so that the image can be saved properly?

Many thanks!

Answer 1

[Philip]

% convert image to intensities
int_vals = mat2gray(im_e);

% save intensities using imwrite
imwrite(int_vals, 'filtered_image.png');

Answer 2

[Sean de Wolski]

 doc imwrite

[Philip]

Thanks! Earlier, I used imwrite to save im_e as both png and tiff. Both file types saved an almost completely white image. Am I missing something that allows me to fix the range of values like I can using imshow? (i.e. imshow(im_e, [0 255])...

[Sean de Wolski]

If you look at the formats in doc imwrite you'll see what the requirements are for each format. Since your images are of class double you'll either need a format that supports double or to convert you images to one of the accepted formats.

[Philip]

Thanks, I played about for a while after your last comment and found that the easiest solution was to convert the data values to intensities using "mat2gray", and then saving the image as a PNG using "imwrite". This function converts the intensities to pixel values automatically before saving.

Thanks again!