Well, I don't think the quality of the image will make any difference if it is a print, so that would be the first thing to determine If you truly have a hand-painted image it would make a big difference on the value. The value of an artist's work depends not only on his or her skill as an artist, but in their popularity. A well-known artist commands a higher value, even if their work is equal to that of other artists. It's all in what people want to buy and what they covet and are willing to pay to get it. It's not just about skill and craftsmanship. So I don't think there is an easy answer to that question, other than looking at the image and being able to see finely painted detail. It may or may not translate into $$.