Wildlife artist David Kitler shares the following tip on using a filter during your painting process:
In order to check whether you have incorporated a wide range of values in your painting, look at it through a monochromatic filter, such as a colored piece of Plexiglas or cellophane. Doing this will allow you to see everything in different shades and values, without the distraction of color or hue.
Because I generally have a lot of green in my paintings, I use a red filter. If your paintings have a lot of red (such as in skin or flowers), use a green filter instead.
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