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
Secondary color (with secondary colors in boldface) are: Secondary color A secondary color is a color made by mixing of two primary colors in a given color space. For the human eye, good primary colors of light are red, green, and blue. Combining lights of these colors produces a large range of visible colors. That is, the primary and secondary RGB colors (with secondary colors in boldface) are: Combining RGB colors means adding light (thus the term "additive color"), and the combinations are brighter. When all three primaries are combined in equal amounts, the result is white. The RGB secondary colors produced