I am a Author of PhotoDune. I upload photos for sales. Can I use this uploading photos any contest? Can I upload also the contest photos for sale in PhotoDune?
It all depends on your contract with Photodune and with the terms of the contest. If you are exclusive to Photodune, you probably cant use the photos in a contest, and you cant upload the photos of the contest to Photodune. Most contest sponsors can do whatever they want with your photos as soon as you enter the contest. But if you are selling as RF non exclusive you can do what you want with your photos.