Copyright laws do apply to photos posted on the internet and i'm aware of some cases where those who have broken the laws have been forced to remove photos ! As a photo collector , in general i'm not against the sharing of photos for the sharing of Knowledge in fact that's why we post , but the problems come if someone has purchased a photo and the copyright sometimes for large sums and then this photo is posted, copied and resold by the unscrupulous as original therefore taking away the uniqueness and value of the original.
Bookmarks