Welcome to WebmasterWorld Guest from 126.96.36.199
You can't add canonical to non-html content.
Link: <http://www.example.com/white-paper.pdf>; rel="canonical"
Google currently supports these link header elements for Web Search only.
implement an external redirect to the canonical url
If you’re duplicating your images across multiple hostnames, our algorithms may pick one copy as the canonical copy of the image, which may not be your preferred version. This can also lead to slower crawling and indexing of your images.
But for almost 50% of the web pages in my website the image urls contain the parameter &value=true.
The parameter is needed to pull the images in website search results pages.
Recently due to some coding changes I have two types of internal links pointing to the same image. One with example.com/image.jpg and the other example.com/image.jpg&value=true