Photochromy, fō′tō-krō-mi, n. the art of reproducing colours by photography.—adj. Photochromat′ic.—n. Photochrō′motype, a photo-process picture printed in colours by any of the ordinary methods of typography in colours. [Gr. phōs, phōtos, light, chrōma, colour.]
Photo-engraving, fō′tō-en-grā′ving, n. a general term including all the various processes of mechanical engraving by the aid of photography.—The term Photog′lyphy is sometimes applied to photo-engraving by one process or other, often limited to photogravure.—adj. Photoglyph′ic.
Photogeny, fō-toj′e-ni, n. the art of taking pictures by the action of light on a chemically prepared ground.—adjs. Photogen′ic, Photog′enous.
Photography, fō-tog′ra-fi, n. the art of producing pictures by the action of light on chemically prepared surfaces.—n. Phō′tograph, a picture so produced.—v.t. to make a picture of by means of photography.—ns. Phōtog′rapher, Phōtog′raphist.—adj. Phōtograph′ic, -al.—adv. Phōtograph′ically. [Gr. phōs, light, graphein, to draw.]
Photogravure, fō′tō-grā-vūr, n. a method of producing by means of photography and the action of acids on a sensitised surface a kind of mezzo-engraving on metal. [Fr.,—Gr. phōs, light, Fr. gravure, engraving.]
Photolithography, fō-tō-li-thog′ra-fi, n. a method by which a photograph in line can be developed with ink so as to be transferred to stone as a lithograph.—n. Photolith′ograph, a print produced by photolithography.—v.t. to reproduce by this aid.—n. Photolithog′rapher.—adj. Photolithograph′ic. [Gr. phōs, phōtos, light, lithos, a stone, graphein, to write.]
Photology, fō-tol′ō-ji, n. the science of light.—adjs. Photolog′ic, -al.—n. Photol′ogist. [Gr. phōs, phōtos, light, logia—legein, to say.]
Photolysis, fō-tol′i-sis, n. (bot.) the movements of protoplasm under the influence of light. [Gr. phōs, phōtos, light, lysis—lyein, to unloose.]
Photomechanical, fō-tō-mē-kan′i-kal, adj. pertaining to the mechanical production of pictures by the aid of light, as in photo-engraving, &c.
Photometer, fō-tom′e-tėr, n. an instrument for measuring the intensity of light, esp. for comparing the amount of light coming from different sources.—adjs. Photomet′ric, -al.—n. Photom′etry, the measurement of the intensity of light. [Gr. phōs, phōtos, light, mētron, a measure.]