Turning A Render Into A Silhouette?

So does anyone if/how you could turn a render into a Silhouette in CS3?

 

Colour overlay

 

if you already have it render or cut out and just the image, just select the image and fill it with black and there you go.

 

colour overlay is the easiest way

 

I prefer using clipping masks with a fill layer (new layer above render, fill layer, right click and select clipping mask), but that's because it is easier to flip on and off compared to color overlay. I generally avoid layer effects because I find most of them obnoxious along with the menu...