Greg,
When you change an original work, you create something else. No, you didn't "destroy" it, but you change its intent or meaning.
Some time ago, this famous artist named Robert Rauschenberg used a photographic reproduction (magazine photo) as part of his own work, a collage. He got rich and famous for this type of "found" art. He was eventually sued by the photographer, who won the case. The photo was the photographer's vision, not his. The reproduction in the magazine was a good representation of the original work and intent, and use was authorized. But he stole it, used it for his own purpose. Didn't care because it was a reproduction.
The point really is respecting the original. Just because the "image" can be reproduced or pooped out of a printer digitally doesn't really matter. Perhaps more philosophical than legal to me, I think it matters. PS, I was a photographer before going into the Navy. Now I just play with model trains, but still like photography enough to write you. Now, how'd you think I'd like it if I found out someone was colorizing my black and white work? Which was all done in the 1970's? Sorry, Gary