Removing Film Grain and Scanner/Camera Noise

Sharpening an image will exaggerate almost all the detail in the image, so any film grain or noise will also get exaggerated (Figures 12.3 and 12.4). That's fine if you want an image with pronounced grain, but if you prefer a smoother look, you might want to check out my techniques for removing grain/noise from your images.

Five main filters are used to remove noise from your images: Gaussian Blur, Despeckle, Median, Dust & Scratches, and Reduce Noise (which is new in Photoshop CS2). (As I discuss this topic, I'll call film grain noise just to simplify matters.) Let's look at these filters one at a time, starting with the least sophisticated and moving to the most advanced. With each filter I describe, I'll show you the results on two images: a simple image that contains different sized black dots that represent noise (Figure 12.5) and a normal image (Figure 12.6) to show how much the filter trashes the real detail in the image. That way you'll be able to see how effective each filter is at removing noise, while at the same time seeing how much of the detail in your images you'll lose in the process.