Generally, Fine / Grain is used for scanned film and Coarse / Noise is used for other digital images. However, Fine / Grain should be used on any high resolution image (above four mega pixels) providing the noise is not too severe. If your image is highly compressed JPEG, low resolution or another very noisy image,  put the Suppression Type selector on Coarse / Noise. If after using the Fine / Grain, Noise setting on a high resolution image and it still appears noisy or grainy, try again with the Coarse / Noise setting.