# how can we find the percentage of similarity between images? and what's the function or algorithms should I used?

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morouj makhlouf on 24 Aug 2019
Commented: Image Analyst on 25 Aug 2019
This is my first time using Matlab so I'm sorry if this isn't clear enough. Thanks in advance for any reply.
I'm currently doing a project on Matlab which is due in the next 4 weeks so this is a little urgent. The project should allow a user to input multiple images and the system should then compare them for similarity.
first I want to made the GUI and allowed the user to input the images and the system can check if the images are similare to eachother .
second I want to be able to compare how the two images are similar in many terms or is this image belong to the same persone or not.
I'm very confused about how to compare/analyse the images for similarity. If any one can point me to the right direction as to what libraries/papers/projects/methods I need for the project or what to do next would be perfect.

Image Analyst on 24 Aug 2019
Edited: Image Analyst on 24 Aug 2019
Not an easy question to ask at all. It can be as simple or as compilcated as you want to make it. You can subtract the images and look for the percentage of pixels that are not 100% equal. But two snapshots of the same scene will most likely tell you almost 100% of the pixels are different. Anyway, you can start with immse(), ssim(), or psnr(). For color images you can look at the global or local delta E color difference. For binary images, you can look at the Sorensen Dice coefficient (see wikipedia). What if I have a photo of some size of my dog, and you have a photo of another size of your dog. Not your cat, but your dog. What kind of metric do you want to say how close or different those two dog photos are? What if it's your cat? They're both house pets, so they're similar, but they're different species so they're different. In general you might Google CBIR (content based image recognition) and start researching.

morouj makhlouf on 25 Aug 2019
Thank you so much
I'll start searching as you told me
Image Analyst on 25 Aug 2019
Here is the image processing database of articles all about image processing: VisionBibliography. Use the search function at the bottom of the page.