Images are a very gray area right now. Its clear you don’t want to copy original, ‘owned’ images. But how do you tell? I have come across only a few ‘watermarked’ images that display an owner out of thousands.
If you are properly attributing the original post, then you are also attributing where the image came from if you curated that post on to your site. Anyone following the attribution will see the original image on the original site. At this point I think this covers most use cases and have not heard of anyone having a problem with it. You could even make it more specific by using an attribution link such as “See original post and this image at: ” (MyCurator allows you to customize your attribution link).
Unfortunately, who knows if the original article you curated actually had permission to use the picture? That I think is the biggest problem. If you go to http://images.google.com/ and then click the little camera icon you can search for an image using the URL of the image (use the image url from the original site). In many cases you will find one or more pages of sites that have used the image. It can take a bit of research to find the actual ‘owner’.
While I feel comfortable curating images with a post, we do offer it as an option so that you can turn off all image capture.
When I create an original post, I use the Zemanta plugin to find a creative commons licensed image – I don’t use any of the images I’ve collected from curated posts without a little research to see if I can find its ‘owner’.
I hope this helps and would like to hear your thoughts in the comments below.