Is a model release form required if its showing the back of a person? No marks, tattoos or other items of reference shown. I can attach the photo if need be.
Here is a link to Adobe's model release requirement...
"Recognition can be based on external factors (for example, other recognizable people, unique clothing, equipment, or location) or personal factors."
Crucial question for you: could the model know it was a photo of themselves?
I dont think so.