Image processing loop after loop

first post ever, and im kinda desperate ...

So there is my code, and i know i can do it by a simple function. But its not the point of the task i have ;(

And my question is how to show an image here correctly. cause disp(array) works perfectly, it shows whole array in matlab window with values from 1 to 255, lovely. But when i want to show it as an image (with imshow after mat2gray) its either black for Imagemy2(n,k)=0; or white for anything else i want to put there. Thank you for your help :)

ImageBasic = imread('rentgen.jpg');

Imagemy = imresize(ImageBasic,[40 40]);

array = zeros(40,40);

Imagemy2= mat2gray(array);

K = 40;
N = 40;

for k=1:K

      for n=1:N
      Imagemy2(k,n)=Imagemy(k,n);

      end
  end
  disp(Imagemy2);
  figure(2);
  subplot(121)
  imshow(Imagemy);
  subplot(122)
  imshow(Imagemy2);

Answer 1

[Walter Roberson]

ImageBasic = imread('rentgen.jpg');
Imagemy = imresize(ImageBasic,[40 40]);
Imagemy2 = rgb2gray(Imagemy);
imshow(Imagemy2)

[Damian Pietron]

will try in a minute, i made everything by premade functions ( mix max filters, median filter, different masks aka 2x2 3x3 4x4, negatives ) and named one of the sections ' hall of shame ' on my paper for labs

and if this will make my problem disapear ill feel dumb

[Damian Pietron]

no, wait, not the problem, image is in grey scale cause its pantomogram ( an x-ray CT)

so the rgb2gray changes nothing

[Walter Roberson]

In the several decades since JPEG was released, I have only seen one legitimate grey-scale JPEG image "in the wild" (that is, outside of test images produced just to prove that it could be done.) JPEG images are almost always RGB images even when they are representing gray tones.

That said, you might want to apply mat2gray() after you do the rgb2gray(). You can test ahead of time whether that is necessary by using the above code and changing

imshow(Imagemy2)

to

imshow(Imagemy2, [])

If your desired image shows up, then you should probably insert the mat2gray() call.

[Image Analyst]

You've marked it as solved, so I assume it's solved. If not, post 'rentgen.jpg' so we can try it.