Removing Film Grain and Scanner/Camera Noise

Four main filters are used to remove noise from your images: Gaussian Blur, Despeckle, Median, and Dust & Scratches. (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 14.7) and a normal image (Figure 14.8) 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. (You might have to look very closely to see if the fine detail is being lost.)