How to change post format from Aside to Image for all posts?

I have a blog where all the posts had the post format Image. This morning I see that somehow they have all been changed to Aside. I’m still trying to figure out how this happened, but in the meantime, how do I go about changing them all back to Image? Is this something I can do with a SQL statement or do I need to write a custom script to loop through all the posts and save them with the Image post format? And if a SQL statement would work, any thoughts on what that might look like?

Thanks much,

Mark