D Duotone 97 In high-quality books, black-and-white photographs are often printed as duotones. As the name suggests, this involves two inks: one ink, usually black, carries the darker tones in the image. A second ink, usually a warm or cool grey, is used for lighter tones. The combination gives the printed images a greater tonal subtlety, close to a real silver gelatin fine print. The two colours need not be black and grey; computer duotones can be created from a greyscale original in any two colours; tritones use three inks and quadtones four. The inks can be designated as spot Pantone inks or process colours from cyan, magenta and yellow. An ink coverage curve is designed so the ink is specific to a particular tonal range.