Another effect option in the Project Settings dialog box is the Noise Grain value. When set to the default of 0, no noise is added to the rendered image, but by increasing this value, random noise is added to the rendered scene. The best example of noise grain is seen when watching or simulating an old-time movie reel that has lines, streaks, and scratches running through the film. This type of effect can be created with a high noise grain value.
Figure 32.5 shows the butterfly image produced in the last example with a Noise Grain value set to its maximum of 128.