This illustration is an exercise on values, it is the continuity of the sketch exercise on the human skull.
The sketch has been reused :
![Digital Painting Crâne 01 Lady Melusine](https://lady-melusine.com/wp-content/uploads/2018/01/Exercice_valeurs_LM_etape_0.jpg)
Secondly the main areas of shadows and lights have been placed.
![Digital Painting Crâne 02 Lady Melusine](https://lady-melusine.com/wp-content/uploads/2018/01/Exercice_valeurs_LM_etape_01.jpg)
And lately, each area has been refined for a more realistic rendering.