Method and apparatus for improving speed of rasterizing transparent images

摘要

A method for improving a speed of rasterizing transparent images, comprising determining, from P graphic entity objects on a transparent page, M transparent images and N nontransparent images. Each of the N nontransparent images includes an intersecting area with one of the M transparent images, P is an integer larger than 0, M is an integer larger than 0 and smaller than or equal to P, N is an integer larger than or equal to 0 and smaller than P, and P=M+N. The method also comprises determining a page-level transparent area and a page-level de-transparentizing area of the P graphic entity objects. Contributions of the transparent images and the nontransparent images to the page-level transparent area and the page-level de-transparentizing area are calculated using different methods. The methods further comprises assembling the M transparent images according to the page-level transparent area and the page-level de-transparentizing area.

主权项

1. A method for improving a speed of rasterizing transparent images, comprising:
determining, from P graphic entity objects on a transparent page, M transparent images and N nontransparent images, each of the N nontransparent images including an intersecting area with one of the M transparent images, P being an integer larger than 0, M being an integer larger than 0 and smaller than or equal to P, N being an integer larger than or equal to 0 and smaller than P, and P=M+N; determining a page-level transparent area and a page-level de-transparentizing area of the P graphic entity objects, contributions of the transparent images and the nontransparent images to the page-level transparent area and the page-level de-transparentizing area being calculated using different methods; and assembling the M transparent images according to the page-level transparent area and the page-level de-transparentizing area, wherein the assembling the M transparent images comprises:
comparing a resolution of each of the M transparent images with a resolution of a device page; and for a low-resolution graphic entity object having a resolution lower than the resolution of the device page:
determining an intersection of the low-resolution graphic entity object with the page-level de-transparentizing area, and obtaining a graphic-entity-level de-transparentizing area of the low-resolution graphic entity object,performing transparency calculation on a color value of the graphic-entity-level de-transparentizing area and a color value of a background graphic entity object to obtain a first calculation result, andmagnifying the first calculation result to the resolution of the device page and drawing the magnified first calculation result according to the page-level de-transparentizing area.