How do I compare two images & recognize the pattern in an image?

Question

How do I compare two images & recognize the pattern in an image irrespective of its size and pattern size, and using .Net C#? Also, which algorithms are used for doing so from Image Processing?

Answer 1

See Scale-invariant feature transform , template matching , and Hough transform . A quick and inaccurate guess may be to make a histogram of color and compare it. If the image is complicated enough, you might be able to distinguish between several sets of images.

To make the matter simple, assume we have three buckets for R, G, and B. A completely white image would have (100%, 100%, 100%) for (R, G, B). A completely red image would have (100%, 0%, 0%). A complicated image might have something like (23%, 53%, 34%). If you take the distance between the points in that (R, G, B) space, you can compare which one is "closer".

Answer 2

I am no expert in image recognition by I once stummbeled upon the AForge library which is written in C# and does image recognition. Maybe it can help...

Answer 3

Techniques for image matching and image recognition can be very different. For the first task, you may make use of SIFT or hand craft your own distance function, based on RGB or otherwise. For recognition, there a vast amount of machine learning techniques that you can use, more popular techniques involves Adaboost, SVM and other hybrid neural networks method. There are no lack of related research papers in this field. Google is your friend.

Answer 4

look up pattern recognition. I known very little about it other than the name.

Warning: If that is what you want, it is one of the hardest "real world" programming problems known.

Answer 5

模板匹配，你可以用EmguCV，OpendotnetCV，Aforge.net做到这一点

Answer 6

Jinmala, you've asked a question here that is extremely broad. There are literally thousands of papers in the literature about these topics. There is no correct answer, and there are many unsolved issues in the comparison of images, so you really probably can't hope for a simple solution that just works (unless your situation is quite simple and constrained)

If you narrow things down, I might be able to help.

Answer 7

You might be looking for this

System.Drawing.Bitmap sourceImage = (Bitmap)Bitmap.FromFile(@"C:\\SavedBMPs\\1.jpg"); System.Drawing.Bitmap template = (Bitmap)Bitmap.FromFile(@"C:\\SavedBMPs\\2.jpg"); // create template matching algorithm's instance // (set similarity threshold to 92.5%)

       ExhaustiveTemplateMatching tm = new ExhaustiveTemplateMatching(0.921f);
            // find all matchings with specified above similarity

            TemplateMatch[] matchings = tm.ProcessImage(sourceImage, template);
            // highlight found matchings

       BitmapData data = sourceImage.LockBits(
            new Rectangle(0, 0, sourceImage.Width, sourceImage.Height),
            ImageLockMode.ReadWrite, sourceImage.PixelFormat);
        foreach (TemplateMatch m in matchings)
        {

                Drawing.Rectangle(data, m.Rectangle, Color.White);

            MessageBox.Show(m.Rectangle.Location.ToString());
            // do something else with matching
        }
        sourceImage.UnlockBits(data);

I warn you it is quite slow takes around 6 seconds to process image of 1024x768 finding in it pciture with the size of 50x50. enter code here

Answer 8

ImageMagick有一篇有趣的文章： http ： //www.imagemagick.org/Usage/compare/#sub-image

Answer 9

Scale-invariant feature transform (SIFT) might be what you're looking for. It's not simple to understand or implement, however.