Free/open library to find similar images

I'm looking for stable and mature free/opensource library allows to compare two images.

I found this one but I want to know if开发者_StackOverflow社区 you use a better one!

• Similar images finder - .NET Image processing in C# and RGB

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I did it simply.Just download EyeOpen Library here. then use it in your c# class and write this:

 use eyeopen.imaging.processing

write

ComparableImage cc;

ComparableImage pc;

int sim;

void compare(object sender, EventArgs e){
    pc = new ComparableImage(new FileInfo(files));
    cc = new ComparableImage(new FileInfo(file));

    pc.CalculateSimilarity(cc);
    sim = pc.CalculateSimilarity(cc);

    int sim2 = sim*100

    Messagebox.show(sim2 + "% similar");

}

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http://opencv.willowgarage.com/wiki/ this one or use this Question if you want to know how can you find it out by you're self Image Comparing and return Percentage