Originally posted by BarryE Quiet legitimate to do copy exactly for training, but he's not been that smart to then submit the work as his own. However ... I've been here as the painter. I've painted something that I liked enough to submit, but then thought hang on it's a copy. So the option then is to approach the original creator of the work. I did this and was given the go ahead to proceed. This potentially helps both parties.
Another option is to rework the original in PS. Just flipping and a change of hue is not enough, but taking a photo and making it your own should be easier enough. Liquify is your friend here. Better to take other photos of the model and create an amalgam - harder, but then it really is the painter's creation.
All round it's a pity that basic curtesy and honesty seems to have been lost here looking at Jingna's Twitter feed. A crappy world we live in ...
Of course. No artist (photographer, painter, what have you) has a monopoly on compositional choices. But monetizing what's basically tracing, and not even citing the inspiration? Absolutely a no-go.
I spent several years in science. No one expects you - you aren't allowed, even! - to make a paper without building on at least a couple dozen prior works. But you always, always give due credit. Your work is your own. But to ignore where it comes from is hubris.