1. A method for visually compositing a group of objects in an image, comprising: using a computer to perform the operations of: determining a modified opacity for a first object in a first group of objects based on a first group opacity for the first group of objects and an initial opacity for the first object in the first group of objects; determining a modified opacity for a second object in the first group of objects based on the modified opacity for the first object in the first group of objects and an initial opacity for the second object in the first group of objects; and determining a modified opacity for a first object in a second group of objects based on a group opacity for the second group of objects and an initial opacity for the first object in the second group of objects, wherein the group opacity for the second group of objects corresponds to a difference between a maximum opacity value and the first group opacity for the first group of objects; wherein the first group of objects is at least partially superimposed over the second group of objects, and wherein the modified opacity for the first object in the first group of objects and the modified opacity for the second object in the first group of objects are used to composite the first group of objects.