A printing process, in particular lithography, in which the image area of the plate carrying the image to be printed is the same height (or on the same plane) as the non-image areas, as opposed to relief or letterpress printing (where the image areas are raised above the non-image areas) or gravure (where the image areas are engraved below the non-image areas). Planographic printing processes use the principle of chemical repulsion between oil-based inks and water to keep image areas and non-image areas separate. The process of lithography (which literally means "stone writing") is less commonly, but more appropriately, called planography. See Lithography.
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