During any baseball (or softball) game, the most common way for the catcher to relay a sign to the pitcher is to use the fingers of his throwing hand which is hidden between his legs to conceal it from the opposing team. The hand signal is given from a squatting position and the hand is positioned between the legs and as close as possible to the catcher's crotch area in order for it to be hidden from the opposing team's base coaches and base runners. One drawback to positioning the hand signals deep between the catcher's legs is that during night games or at dusk, shadows are created between his legs and the signals become more difficult for the pitcher to see and understand. The clarity of the catcher's signals is diminished during day games as well, when direct sunlight creates a shadow over the catcher, thus creating a dark background in the signal area. The color of the catcher's equipment, specifically dark colored equipment, may also hinder the visibility of the signals.
USPTO Backgrounds
USPTO Backgrounds