A method of compositing a grouped plurality of graphical objects with an image (D 0), said grouped plurality of objects and said image having associated colour and opacity component values, said method comprising the steps of: copying the image (D 0) to form an image copy (D 1), which initially has the same colour and opacity component values as the image (D 0); generating at least one opacity channel (D a(d)) having associated opacity component values, which are initially set to fully opaque; compositing (704, 705) the colour and opacity component values of each object of the grouped plurality of objects with the colour and opacity component values of said image copy (D 1); compositing said opacity component values of each of said objects with that of said at least one opacity channel to produce an altered opacity channel (D a(d) '), said altered opacity channel thereby representing the opacity component values associated with said image remaining in said image copy following composition with said colour and opacity components of said objects of the grouped plurality of objects; utilising said altered opacity channel (D a(d) ') to remove the colour and opacity component values of said image (D 0) remaining in said image copy (D 1) following composition with said colour and opacity component values of said objects; inverting said opacity values of said altered opacity channel (D a(d) ') by subtracting said altered opacity channel (D a(d) ') from a fully opaque opacity value; applying a group opacity to said grouped plurality of objects; utilising said altered opacity channel (D a(d) ') to composite the colour and opacity component values of said objects with the colour and opacity component values of said image (D 0). copying the image (D 0) to form an image copy (D 1), which initially has the same colour and opacity component values as the image (D 0); generating at least one opacity channel (D a(d)) having associated opacity component values, which are initially set to fully opaque; compositing (704, 705) the colour and opacity component values of each object of the grouped plurality of objects with the colour and opacity component values of said image copy (D 1); compositing said opacity component values of each of said objects with that of said at least one opacity channel to produce an altered opacity channel (D a(d) '), said altered opacity channel thereby representing the opacity component values associated with said image remaining in said image copy following composition with said colour and opacity components of said objects of the grouped plurality of objects; utilising said altered opacity channel (D a(d) ') to remove the colour and opacity component values of said image (D 0) remaining in said image copy (D 1) following composition with said colour and opacity component values of said objects; inverting said opacity values of said altered opacity channel (D a(d) ') by subtracting said altered opacity channel (D a(d) ') from a fully opaque opacity value; applying a group opacity to said grouped plurality of objects; utilising said altered opacity channel (D a(d) ') to composite the colour and opacity component values of said objects with the colour and opacity component values of said image (D 0).