If, for instance, you want to find out if an image is on the web, you can do an image search with Google. The easiest way to do an image search on iPad, is to use Google Chrome browser. This is how you do:
Open the image in Google Chrome.
Tap and hold on the image until a pop-up opens.
Tap Search Google for This Image in the pop-up.
Search results will be shown in a new tab.