Get More Realistic Drop Shadows On Press
Here's a quick tip for getting more realistic drop shadows in print: Add some noise. When you choose Drop Shadow from the Add a Layer Style pop-up menu in the Layers palette, there's a slider for adding noise to your shadows in the Layer Style dialog. When you add just a small percentage, it makes your shadows appear more realistic when they show up in print.
That’s a real old tip. Adding noise to gradients and other smooth transitions helps make them look more realistic and prevents banding.