title: How to compare image similarity using php regardless of scale, rotation?
body: <p>I want to compare similarity between below images. Acording to my requirements I want to identify all of these images as similar, since it has use the same color, same clip art. The only difference in these images are rotation ,scale and the placement of the clip art. Since all 3 t-shirts has used the same color and clip art I want to identify all 3 images as similar. I tried out the method described in <a href="http://www.hackerfactor.com/blog/index.php?/archives/432-Looks-Like-It.html">hackerfactor.com</a>. But it doesn't give me correct result acording to my requirements. How to identify all these images as similar?DO you have any suggestions? Please help me.</p>
  
  <p><img src="https://i.stack.imgur.com/D8ct1.png" alt="enter image description here">
  <img src="https://i.stack.imgur.com/xNZt1.png" alt="enter image description here">
  <img src="https://i.stack.imgur.com/kjGjm.png" alt="enter image description here"></p>
  
  <p><strong>The below images should be recognized as different from above images.(Even though the tshirts has the same color, clip arts are different. Last tshirt is different from above, because it has use the same clip art, but twice. )</strong></p>
  
  <p><img src="https://i.stack.imgur.com/WIOHs.png" alt="Image A">
  <img src="https://i.stack.imgur.com/ljoBT.png" alt="Image B">
  <img src="https://i.stack.imgur.com/qEKSK.png" alt="Image C"></p>