Ask HN: Need help w/ external image preview like FB then image capture

Hi, Non-technical founder doing some research to try and help point my developer in the right direction. Seeking resources or guidance to help generate an image preview from a link, similar to the one used in Facebook's UI, and then subsequently also allow a user to display / grab the full size image of the preview as well. Not looking to necessarily create a bookmarklet a la svpply.com or the like, but interested in figuring out a way whereby a user can enter a link, select the image they want on the page they've linked to, and then have that image added to a post or submission to a web page. Also, given that I'm working on a product in the fashion/style space I'm wondering what this solution might be if applied to pages with flash or other platform that might not host images in a traditional way. Any help, guidance, or anything would be greatly appreciated! Thank you!