Abstract: 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.

Abstract: Methods and apparatus that blend graphics data. In a printing device, a first object is received and rendered into a frame buffer; a second object including blending instructions is received for blending with the first object; and rendered data associated with the first object is retrieved from the frame buffer and a blend of the two objects is rendered according to a user-selectable blending algorithm. The frame buffer may be a deep frame buffer. The blended data printed may be of a bit depth reduced from that of the frame buffer. The reduced bit depth may be achieved by halftoning the blended data. The blending algorithm may be transparency, shadow, overprinting, darkening, lightening, screen effect or additive effect. The blending instructions may include a blend operator defining a blend algorithm for blending two objects.

Abstract: A raster image processor receives a file of instructions and images in any convenient page description language and blends the images in accordance with the specified blending mode and, possibly, opacity information.

Abstract: Methods and apparatus for blending graphics objects. In one aspect, a method includes receiving a first graphics object; rendering the first graphics object to produce a first pixel map having a first bit depth; increasing a bit depth of a second pixel map associated with a second graphics object that is to be blended with the first graphics object, where the second bit depth is less than the first bit depth; and blending the first and second pixel maps. The method may be implemented to blend graphics objects received by a printing device. In one embodiment, the invention features blending deep pixel data received by a printing device with corresponding shallow halftoned data stored in a shallow frame buffer. The invention may be implemented as a printer configured to receive a page description language description of a page to be printed, the printer including a dehalftone engine for deriving deep pixel data values for objects stored in a shallow frame buffer.

Abstract: A large set of image data values are associated with a smaller set of values, such as color palette look-up table (LUT) indices, to create an inverse table. The larger set of image data values address into the inverse table. The inverse table is simulated as a symmetrical N-dimensional structure in computer memory, with N being the color dimension of the image data values. Generally, a set of star spaces in the structure are captured by the color palette LUT indices; the capturing is based on some relationship such as the relationship between the image data values and the color palette values indexed by the color palette LUT indices. The remainder of the structure spaces are captured by performing a uniform and iterative expansion away from each star space, capturing each uncaptured space encompassed by the expansion until all spaces are captured.