Color printing newspapers and magazines, brochures, cards, posters and similar mass-market items. In this type of industrial or commercial printing, the technique used to print full-color images, such as color photographs, is referred to as four-color-process or merely process printing. Four inks are used: three secondary colors plus black. These ink colors are cyan, magenta, yellow and key (black); abbreviated as CMYK. Cyan can be thought of as minus-red, magenta as minus-green, and yellow as minus-blue. These inks are semi-transparent or translucent. Where two such inks overlap on the paper due to sequential printing impressions, a primary color is perceived. For example,
Combination printing often necessary to add artistic techniques to photographs. Discussing the benefits of composition in the art of photography and using combination printing, Robinson wrote, in "Pictorial Effect in Photography", that the method of combination served to "produce an agreeable presentation of forms and tones, to tell the story which is to be elucidated, and to embody the spirit of what it is intended the picture shall represent or suggest." His writings show his knowledge and his passion for creating new content in his photos with using this process. During the Victorian Era, another proponent of the technique of combination printing