You have my permission to use these images as long as its not used for exploitation of people. I am always delighted with traditional arts studies, art students and working artists that use my work for their art. Photo manipulations are certainly allowed, and I have no problem with DA prints as long as you follow my rule on how you use my image and that you do some serious work on it before you offer it as a print. I don't mind that you might experiment and learn to use various digital filters, color adjustments and such, but that sort of work should be acknowledged as a process of learning, not a finished work.
I am pleased to be able to help folks learn, as well as produce quality art and develop their visions of the world. Do drop me a note with your work if you use any of my stock.
Now get out there and create something!