Let's say you have a large multilingual site and all your pages are translated into the localized language. So page A in the US has the same content as page X in France, but the content is translated into French on page X. The image however is generic enough where that image is good for all the pages it was translated into.
Google says if you have the same image for those pages, you should not change the file name of the image, you should not translate the filename of that image.
John Mueller from Google said in a Google Webmaster Hangout at the 22:07 mark "I would just keep one version" and it should make it "a lot easier for crawling, it makes it a lot easier for image indexing as well."
In short, do not translate the image filename if the same image is being used elsewhere. Keep that filename and URL for the image so Google does not need to consolidate the images on their end.
Here is the video:
Here is the partial transcript - you can rewind if you want to hear the full question:
I would just keep one version. So we do use the file name as a really small factor when it comes to images but we use the text on the page much stronger. So if the the text on the page is already translated and that's that's kind of what you want. And in the background if we see multiple files that lead to the same content like the same image with multiple file names. We'll treat those as duplicates and fold that into one URL anyway. So if you can avoid us having to struggle with this by telling us like this is that one image and this is the only URL that points to that image. Then that makes it a lot easier for crawling, it makes it a lot easier for image indexing as well.
Forum discussion at YouTube Community.
