Music notes..............
This answer is going to be true
One of the important factors that was used is the inner essence of the subject. Such as the expression of the character, facial, eyes, moral quality as such.
The turuth is that when artists pass away, the supply most likely becomes collector's item or a memorabilia.We know this because these items are thought to be of high value and the items are sold at high prices or are kept in a museum. Hope this helps better