1. A method for determining the color of a pixel representing part of a translucent object within an image, the image representing a virtual scene, the method comprising: providing an initial color of the pixel; providing a light source in the virtual scene, the light source having an initial illumination value associated therewith; generating a depth map for the light source; determining a transmittance distance based on the depth map and the distance between the pixel and the light source, the transmittance distance indicating the distance light travels through,the translucent object; and calculating a decayed illumination value based on the initial illumination value, a decay function and the transmittance distance.