The Google Image/Image search is an amazing new feature which is derived from Google's use of sophisticated image recognition functions to satisfy a need to eliminate duplicate images from Google's Image search. You may have noticed that over the years, the old problem of seeing the same picture over and over again in Image search has disappeared. Now, Google allows its users to harness this powerful tool for their own purpose. Thank you, Google.
Go to Google Images, and type in your search term, example, "widget propellers."
If you find an image that's yours on the page, click on it, and drag and drop in in the search box which will automatically enlarge when you hover over it. Like this:
Image/Image search is a revolution in your ability to detect infringements on your graphical content.
Your search result page will point out all your indexed image's twins on the internet:
Scan this search result page for images attributed to Pinterest.com.
Open in fresh tabs, collect link and image locations.
NOTE: Currently, pins appear poorly indexed in this feature. It's not impossible that Google considers Pinterest's content so likely to be duplicate content that it applies a severe penalty against it in its Image search, but this is just speculation. Using the "site:" command in Google Image does yield a bevy of Pinterest Images, so they are in fact indexed for Google Images. There are mysteries.