title: artifacts in processed images
body: <p>This question is related to my previous post <a href="https://stackoverflow.com/questions/10863734/image-processing-algorithm-in-matlab">Image Processing Algorithm in Matlab</a> in stackoverflow, which I already got the results that I wanted to. </p>
  
  <p>But now I am facing another problem, and getting some artefacts in the process images. In my original images (stack of 600 images) I can't see any artefacts, please see the original image from finger nail:</p>
  
  <p><img src="https://i.stack.imgur.com/5hM3u.png" alt="enter image description here"></p>
  
  <p>But in my 10 processed results I can see these lines:</p>
  
  <p><img src="https://i.stack.imgur.com/QO2yM.png" alt="enter image description here"></p>
  
  <p>I really don't know where they come from? </p>
  
  <p>Also if they belong to the camera's sensor why can't I see them in my original images? Any idea?</p>
  
  <p><strong>Edit:</strong></p>
  
  <p>I have added the following code suggested by @Jonas. It reduces the artefact, but does not completely remove them.</p>
  
  <pre><code>%averaging of images
  im = D{1}(:,:);
  for i = 2:100
   im = imadd(im,D{i}(:,:));
  end
  im = im/100;
  imshow(im,[]);
  
  for i=1:100
  SD{i}(:,:)=imsubtract(D{i}(:,:),im(:,:))
  end
  </code></pre>
  
  <p>@belisarius has asked for more images, so I am going to upload 4 images from my finger with speckle pattern and 4 images from black background size( 1280x1024 ):</p>
  
  <p><img src="https://i.stack.imgur.com/0dPEl.png" alt="image1">
  <img src="https://i.stack.imgur.com/8rzW1.png" alt="image2">
  <img src="https://i.stack.imgur.com/gjUcq.png" alt="image3">
  <img src="https://i.stack.imgur.com/UiuKK.png" alt="iamge4"></p>
  
  <p>And here is the black background:</p>
  
  <p><img src="https://i.stack.imgur.com/ENVl1.png" alt="blackbackground1">
  <img src="https://i.stack.imgur.com/RCx97.png" alt="blackbackground2">
  <img src="https://i.stack.imgur.com/JcW9X.png" alt="blackbackground3"></p>