sharpening picture using unsharp - please check my code

I have a grayscale picture, uint8 jpeg. The picture is about a blurred tomato. I tried to do some unsharp, I tried to blur it, take it edges, and add to the original one. But it seems different. Im using matlab 7.9.0(r2009b)

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blur_filter = [1/9 1/9 1/9; 1/9 1/9 1/9; 1/9 1/9 1/9];

tomato = imread('tomato.jpg');

blur_filter = blur_filter / sum(sum(blur_filter));

blur_tomato = imfilter(tomato, blur_filter);

edge_filter = [-1,-1,-1;-1,8,-1;-1,-1,-1];

edge_tomato=imfilter(blur_tomato, edge_filter);

sharp_tomato = tomato + edge_tomato;

subplot(2,2,1), image(tomato), title('Original tomato');

subplot(2,2,2), image(blur_tomato), title('Blur tomato');

subplot(2,2,3), image(edge_tomato), title('The edge taken from the 
blur');

subplot(2,2,4), image(sharp_tomato), title('Sharp tomato');
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sorry i dont know how to attach the picture here.

The problem is, I get pictures like a vision of predator from the predator movie, if you get what i mean.

[Chandra Kurniawan]

Would you upload your image??

I just wonder how can 'tomato' image becomes 'predator' image after you perform edge_detection on that.

[Walter Roberson]

http://www.mathworks.com/matlabcentral/answers/7924-where-can-i-upload-images-and-files-for-use-on-matlab-answers