Starting to understand the layer functions in AP. I use a white rectangular layer between background and the layer that I draw on; this white layer's opacity I change to see the background and the result of my drawing. Mostly used various (customized) Brushes, the Smear tool and the Burn and Dodge tool. Some effect filters. This portrait was drawn from scratch and many temporary layers have been merged down. Actual size of the portrait is 60 x 46 cm, reference image was a small b&W photograph. What I would like to see in the Layer Adjustment functions is a button to see the original state to compare with applied function.