There are thousands of images in the millions of web pages across the internet. These images can prove to be very useful to drive traffic to your website, through Google Image search. Adding a relevant image that can explain the content of your web page in a simpler way is a sure way to attract traffic. Every image that is a part of the web pages should have a web address, which is called the Image URL.
Just like the web pages are crawled, processed and indexed the images on the web pages are also crawled and indexed. So, if there is any change in the URL of the images of your web pages then there will definitely be changes to your search rankings. The search rankings are affected and as always, they can get higher or lower than before.
When you change the URL of an image, though it is the same image that comes up on the same page, Google will treat it as a new image. Google will now have to recrawl, reprocess and reindex this new URL, so that it can work its way through the rankings. This will take more time because the images are not recrawled and reindexed every now and then. This situation of changing Image URLs for the same image on the web pages was raised and addressed at a recent Google Webmaster Central hangout.
Insert Image redirects
This situation in the image search rankings can be moderated by inserting redirects for image URLs. Redirecting the old image URLs to the new URLs will establish a relation between the two images. This will enable Google to forward all the ranking signals from the old image to the new image, making the new image to retain the rankings. This should lessen the burden of changed search rankings to the web pages. If your website is one of those that get a lot of traffic from google image search, then make sure you use image redirects.
In case of significant changes made to the image URL on your web page, Google says that it will take longer time to reprocess them. Making sure that the image redirects are set up will avoid any problems in the search rankings. Since the image redirects are not visible when a web page is loading, you will not know if there is a redirect from the old image URL to the new one. With proper attention given to take care of this, any disruptions to the traffic arising from the google image search will be covered.