Political colour which dates back to the French Revolution in the 18th century and the revolutions of 1848. Before this nascence, the colour red was generally associated with monarchy or the Church due to the symbolism and association of Christ's blood. The colour red was chosen to represent the blood of the workers who died in the struggle against capitalism. All major socialist and communist alliances and organisations—including the First, Second and Third Internationals—used red as their official colour. The association between the colour red and communism is particularly strong. Communists use red much more often and more extensively than other ideologies
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