Facing colour engineers and support corps normally had a single branch colour, although exceptionally each regiment of Swedish artillery had its own facing colour until 1910. The United States regular army after the American Civil War adopted a universal dark and light blue uniform under which each regiment was distinguished only by numbers and other insignia, plus branch colors. The latter were yellow for Cavalry, red for Artillery and white (later light blue) for infantry. Combinations of colors such as scarlet piped with white for Engineers, orange piped with white for the Signal Corps and black piped with scarlet for Ordnance personnel
Colour cast used to reduce the blueish tint caused by daylight. Blue filters reduce the orange colour caused by incandescent light. A variety of coloured filters in varying degrees of intensity are available. Kodak's amber filters, for example, vary from palest yellow ("81C") to deepest amber ("85B"). A photographer chooses which filter to use based on the quality of the ambient light. Colour temperature meters can read the temperature of the existing lighting conditions and guide the selection of the filter. Clouded sky, for example, requires a paler amber than clear blue sky. If a filter is unavailable, flash is an alternative