Google’s John Mueller advises site owners that changing image URLs will affect how they rank in image search results. This is a great advantage for websites that get a lot of traffic from Google Images.
Changing an image URL will actually result in Google treating it as a new image. That could take some time, as Mueller notes because images are not crawled as often as web pages. But it’s worth it.
Image search rankings topic came up during a recent Google Webmaster Central hangout where the following question was submitted:
We’ll have a technical change in our shop that will change all of our image URLs… Does Google know that this is the same picture? Or will we lose rankings? Should we set up redirects for image URLs?
Mueller responded with an emphatic “yes.”
Changing image URLs will definitely have an impact on how those images rank. On the other hand, the damage can be mitigated by setting up redirects. Redirecting old image URLs to new URLs will transfer ranking signals from the old images to the new ones.
Mueller says, that using redirects is a great way to deal with the situation. Avoid changing image URLs it at all possible. But, if you need to do it, make sure redirects are in place.