On Saturday’s post we looked at color constancy illusions, which prove how hard it is to judge a color note accurately. There are various methods to overcome the problem, most of which involve isolating a particular spot of color. One way is to look through the hole in a half-closed fist. Another is to hold up two fingers spread slightly apart and look between them.
Other artists have developed special viewing scopes for isolating colors. You can make one yourself by painting a 3x3.5 inch card half white and half black. Then punch a hole in each corner. Looking through those holes allows you to isolate a given color against white or black. You can also compare two different nearby colors through side-by-side holes. You can test a mixture by putting a daub of paint next to the hole.
The limitation of any such device is that the illumination on the scene may so far exceed the range of your pigments that no single one-to-one match is possible. A related problem is that the tone of the white card changes as the illumination on the card changes, so you have to hold the card exactly at the right angle relative to the light to get a useful comparison.
Previously: Color constancy.