Gum bichromate negatives of cyan, magenta, and yellow or red, green, and blue are used for a full-color image. Some photographers prefer substituting the cyan emulsion in the CMYK separations with a cyanotype layer. A simple duotone separation combining orange watercolor pigment and a cyanotype can yield surprisingly beautiful results. Low density photographic negatives of the same size as the final image are used for exposing the print. No enlarger is used, but instead, a contact printing frame or vacuum exposure frame is used with an ultraviolet light source such as a mercury vapor lamp, a common fluorescent black light, or the
Additive color Additive color Additive color is a method to create color by mixing a number of different light colors, with shades of red, green, and blue being the most common primary colors used in the additive color system. Additive color is in contrast to subtractive color, in which colors are created by subtracting (absorbing) parts of the spectrum of light present in ordinary white light, by means of colored pigments or dyes, such as those in paints, inks, and the three dye layers in typical color photographs on film. The combination of two of the standard three additive primary colors in