| 摘要 |
A method of creating an image utilizing a table of levels known as a "level activation table" ( 34 ) is disclosed. The method uses the level activation table to optimally evaluate a given compositing expression such that the number of pixel operations needed to evaluate the expression is minimized. The method determines the smallest regions in which compositing operations need to be performed and uses these regions to produce the level activation tables where clipping is applied to operations in order to avoid redundant and/or incorrect pixel operations. The method is preferably used in a compositing model in which objects are composited onto a page using a stack machine and an associated compositing stack ( 38 ). The stack 38 may be manipulated using standard stack operations such as push, pull and pop. Instructions for the stack machine are taken from the level activation table 34. |
