Alphonse Mucha—Jaraslova—c 1930
Why does an artist feel the need to create a drawing or painting based on a photograph, when that photo is perfectly serviceable as a likeness of a person? Because he or she can. The nuances of differences that an artist infuses in the work interprets the subject with more 'reality' than most photographs.
The portrait painting, in oil, by Mucha of his daughter Jaraslova is very satisfying to look at, even without knowing anything about the subject. Mucha has made a personal interpretation of someone he cares deeply for, and we are privileged to see through his eyes and heart.
The photograph, below the painting, is also satisfying to look at and could stand on its own as an artistic document, but the painting communicates on a transcendent level and is what we consider 'art'.
Mucha painted many young women as subjects in similar poses over the years, yet many of them would not be considered 'portraits'. Many of those were idealized portrayals, but this painting we know immediately to be a real person. When is a portrait a portrait, and not just an image of a person?