in stock WP, it's hard to believe how difficult it is to simply move an image between one page or post or gallery and another. Basically you can't do it - you can't even detach an image from a page and then reattach it. You basically have to delete the image from the database, upload it again, rewrite all the title and alt and comment tags, etc. So deeply stupid. Anyway this nice little plugin allows you to go into Image Edit, and quickly choose another page to attach the image to. It also works if that image is in a 'gallery' attached to that page.
Although it would be nicer if you could check off a bunch of images and bulk-action reattach them to another page. But, sure is a vital function and a big improvement. Thank you.