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.