The New York Times has been publishing images without captions at least once a week since August 2016 and posting the following prompt:
After looking closely at the image, think about these three questions:
• What is going on in this picture?
• What do you see that makes you say that?
• What more can you find?
This process is similar to Notice/Wonder which is really useful in math, science and social studies.
Some examples of the many images on the site.