this is the book about light and shadow in digital painting. Or you can call it grayscale painting. I'm sharing what I was learning in the past years. In truth, I was really struggling to understand what is value for about 6 months by now. There are good and bad in it, I truly believe by seeing them both together can improve your sense of what looks good, what doesn't. You can decide yourself, and finally, upgrade your judgment in art design.