Remove noise from an image

Hi everybody, I am a student and I am at the beginning in a course of Machine Vision. It is one week that I try to solve this problem but without success so maybe someone can help me. I have to remove the noise and improve the quality of this image http://www.filedropper.com/image_5

Can you explain me how it is possible a show some code?

Thanks

Ale

Answer 1

[Sean de Wolski]

I2 = bwareaopen(I,3);

[Alessandro]

It doesn't work! I got a completely withe image.

[Sean de Wolski]

It was a shot in the dark. I didn't download your image (I don't trust the site). I also don't want to do your homework for you. If you posted your image to a site that's trustworthy (i.e. no download; e.g. www.uploadhouse.com) and showed us, in code, what you've tried so far, we'll be able to give you non-useless answers.

Answer 2

[Alessandro]

This is the image: http://img8.uploadhouse.com/fileuploads/10299/10299638860eea3f63a6d0d4279798a3ec3fbba3.jpg

This is my code so far:

I = rgb2gray(imread('L3S1T2.jpg'));
imshow(I); title('Original');

figure;
imhist(I);

B = wiener2(I);
figure;
imshow(B);

I thought that the noise could be a Gaussian Noise so I applied a wiener filter but the result is not so good. Then looking in the histogram I saw some spikes and I thought that maybe the spikes are related to the noise, so I am looking for a way to "remove" the spikes.

Answer 3

[Sean de Wolski]

X = imread(your_image);
Q = uint8(imclearborder(imfill(conv2(double(X(:,:,1)),ones(3),'same')<1400,'holes'))).*X(:,:,1); %quarters
imtool(Q)

[Alessandro]

This doesn't look like a real improvement.

And I don't want only the solution, if it is possible I would also understand and learn something.

[Sean de Wolski]

That was the point. I have you six things to look into that you may find useful: convolution, hole filling, extraction of one slice, threshold, border clearing, map application. You can play with the parameters and or look at other functions such as imdilate, imerode, bwdist...