Blending image data using layers

摘要

Methods and apparatus for blending graphics data that includes a plurality of objects. In one aspect, objects are grouped into two layers; objects associated with a first layer are drawn; objects associated with a second layer are drawn; and data drawn into the first and second layers is blended. A layer stack may be used to define a hierarchy for blending layers of the image. The apparatus may be an output display device and more particularly a printing device. The object data may be transformed to an intermediate form and the intermediate form data for the first and second layer may be blended. The apparatus may include an interpreter for receiving object data associated with two layers of an image and for receiving a layer operator for designating which objects belong to which layer; a drawing engine for drawing objects into a first and a second buffer for a first layer and a second layer, respectively; and a blend processor for blending data in the first and second buffers. The apparatus may be a printer configured to receive a page description language description of a page to be printed.