There are several tool that can track the Google search results, and they have been showing an increase in the percentage of time that Google shows image results in the core web results. The image search result box the might be displayed in the main search results now displays for a third of all queries according to some reports. SEOClarity published their data this morning showing “images in the Top 10 leaped from an approximately 24% occurrence to a 34% occurrence.” The increase has started around April 13.
You can see the image box for several types of queries where Google thinks you might be interested in seeing image search results.
SEOClarity shared their data showing the spike in image search results showing up in Google. Here is their chart:
Mozcast data shows a similar trend: