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two-color reproduction from a monochromatic halftone original (for example, a black-and-white photograph). Two screen negatives are made from such an original, without using a light filter; one of the negatives has higher contrast, and the other is softer. The first negative is photographed with the screen in the normal position; the other, with the screen rotated through 30°-45°. The plate from the negative with higher contrast is used to print in black (the contour plate), and the plate from the second negative is used to print in colored ink, usually pale yellow, blue, or green. The rotation of the screen when photographing causes a shift of the points of the screen of the first plate with respect to the points of the second plate; as a result, moiré does not occur and the screen points of one color do not overlap those of the second upon printing. Duotone intensifies the effect of a monochromatic halftone image.