In black & white, everything being a question of nuances and contrasts. These filters constitute a powerful method of expression, no matter what the subject is. Used in color, they generate effects that are absolutely spectacular! Keep in mind a simple rule: to brighten a colour you must choose a filter of the same colour, and, to darken, you must use a filter of complementary colour. Thus, a green filter will brighten vegetation and a orange or red filter will darken the sky.