How can I remove noise from an image with Matlab?

Question

I need to remove the noise from this image using matlab http://www.flickr.com/photos/63036721@N02/5742366240/in/photostream

The aim is to improve the quality of the coins and, if it is possible, to see the shape inside them.

I thought that maybe it is a gaussian noise so I tried to use the Wiener filter but it don't work so good. Is really gaussian noise?

Thanks

Answer 1

This is salt and pepper noise. Apply a median filter. It should work.

http://www.mathworks.com/help/toolbox/images/ref/medfilt2.html

• Alessandro: I am not sure that this is salt-and-pepper because looking at the histogram I can not see many pixels totally white and many totally black, indeed the median filter don't work so good.
• R1234: Can you please post the image of the histogram?
• R1234: ok. I really can't try things out because my license for matlab has expired. Do you see those peaks in the histogram? Those are the values which need to be deleted. Please post the images corresponding to 1. gaussian 2.median 3. min filter. Gonzalez and Woods- Digital Image Processing 3rd edition is a good reference for all the various filters in it. Is it a college assignment?