Preparing the Material
When selecting and editing source material for the sketch, it’s very important that you keep a few things in mind. These are not hard-coded rules, but rather best practices that have worked well in my work.
If you want to use a portrait photograph as input, that portrait should be cropped to white. You can use a normal image editing program to do this. The image should show a recognizable face with the mouth closed. Smiling too much does not work very well in my experience. For people with long hair, tie it in a braid if possible, since open hair is hard to crop and frays unattractively on the result.
I have always cropped the portraits in all projects so that the head is in the center of the visual. However, this requires cropping the body, which creates hard edges. This does not work well at all in the visual, unfortunately. Hard edges must be erased with a soft brush or eraser in the image editor.
