I have taken pictures several times and turned them black and white in order to see the values as I was working. It helps to choose emphasis areas as well as my use of dark and light colors.
The entire time I have been working, which is significant with a painting such as this, I have endured the company of a critic, a visiting resident cat, Chiquita. She wants to be close as possible to me and the stool in the picture isn't close enough for her. She would paint with her nose if I let her. She would be in my lap if I was not standing to work.
Chiquita the critic also likes to rearrange my set up.