There was a time when film grain was a problem for some photographers. That concern translated into a concern with digital noise. Many words have been written on the techniques in many applications to remove or lessen digital noise or grain
in modern images. Some even seek to find ways to remove the grain from old film photographs. Despite all of this, grain has its place in modern digital photography. Grain now brings with it the charm and nostalgia of bygone film days. When compositing images, grain can be the unifying effect bringing different images from different times together for a great composite. Adding grain to a black and white or sepia image can add a pleasing artistic texture to the work. Whatever the reason, many photographers add grain to an image. Sometimes after working diligently to remove digital noise! But, then, grain isn't noise.
Enter one of Lightroom 3's quiet features -- the Grain panel.
Tucked away in the Develop module, it's the bottom half of the Effects panel. There are three sliders that control the grain applied to your image.
Until the Amount slider is greater than 0, the Size and Roughness sliders are inactive. First decide how much grain to add by moving the Amount slider to the right.
Now we can see the Size and Roughness sliders are active. Size will control how big or small the individual grains are while Roughness varies virtual texture of the grain. Work with the sliders until you achieve the look you like. Examine the image at several different zoom levels to see how well the grain fits into your artistic vision. Adjust as needed.
Its a good idea to look at a before and after view every so often so you can really see how different your choices have made the image.
So tap into your inner artist. Spread some grain and see what grows!