Image comparison in website from database

I wanted to do a web project based on image comparison. It will be like the user will input a picture of a shirt and my project will show the user if a similar type of shirt is available in any store. I thought to web scrap all the images of shirts from 3 or 4 sites then store them in my database then I want to compare the inputted image with the images in my database. If the similarity is 70% or above then I want that shirt to be in the output list. Now my question is how would I able to do the comparison on my website? I want to compare the shirt design and shirt color. Thank you!