Sir Walter Scott, photogravure of the 1823 portrait by Sir Henry Raeburn

From: The Scott Gallery: A Series of One Hundred and Forty-Six Photogravures together with Descriptive Letterpress, ed. James L. Caw (Edinburgh: T.C. & E.C. Jack, 1903)

Photo-engraving involved transferring a photographic negative of a drawing, painting, or object to a metal plate, and then etching it in.