I'm going to create a new ction set for Photoshop to add more realistic film grain effects. I'd like to do this in a more open and community-like fashion. That means, I'd like input here, using the comment system.

The Typical Approach

Nearly every tutorial and action starts with a layer filled with midtone gray. An overlay layer blend is added. Since the layer is filled with gray, this means the overlay layer has no visible effect until the Add Noise filter is run.

This is the heart of nearly every film grain effect. Many stop right there, just finessing the settings for the Add Noise filter and the layer's Opacity. Others run some light sharpening or adjust the contrast of the grain.

Not Very Realistic

My guess is that the advocates of the typical approach have very little experience with B&W film and B&W enlargements.

Here's a few problems that should be obvious . . .

1. Noise from Add Noise in Photoshop tends to be too small. Some B&W films had very fine grain. But there were also some really grainy films. Older films, for those who want a more vintage look, tended to have larger grains. A realistic film grain effect needs to be able to build up the grain.
2. At the low levels recommended in most tutorials, noise from Add Noise tends to be too uniform. Silver halide grains were not completely arbitrary in size, but they also were not perfectly uniform. Grainier films tended to have grain that would clump together. A realistic film grain effect should have grain in several different sizes.
3. Film grain was not uniformly evident in the shadows, the middle tones, and the lightlights. Grain tended to be more obvious in the middle tones, the quarter tones, and the three-quarter tones. A realistic grain effect should "roll off" in the extreme shadows and highlights.
4. If you have ever scanned B&W film and looked at it closely, you'll notice that film grain is more obvious in the Blue channel, less in the Green channel, and less yet in the Red channel. If you're going to mimic B&W film grain, you need to work with individual channels in Photoshop.
5. You can also get "reverse grain" with small white grain-like specks in shadows.

What Can Be Done in Photoshop

We can approach each of these features with more or less success in Photoshop. I'll work up a tutorial as we go along, so everyone understands the techniques, but we'll want to do this with Photoshop actions and maybe even scripts. To do the job right, a lot of steps will be involved.

Recent versions of Photoshop include an Artistic filter called Film Grain. It is possible to use it. The downside is this: it's an 8-bit filter. I avoid it for that reason and use the Add Noise filter instead and ehen refine the effect.

• Film Grain Size. This can be manipulated in at least two ways.

  One possibility is to yank up the Amount setting for the Add Noise filter. If you use something like 400%, the grain sizes show lots of variation. There will be a very evident clumpiness to the noise. In fact, it will likely look quite scary. No big deal, since that's what layer Opacity adjustments are for. If the grain is too large, the effect can be applied to a larger copy, reduced, and copied back.

  Another possibility is to create a smaller copy of the image, add noise to that, resize it back to normal, and then copy the noise layer. That will magnify the faux film grain. A script would have an advantage here, since a script can read image dimensions and create a duplicate at a fixed reduction.

• Applying Grain to Shadows, Middle Tones, and Highlights. The idea is to "roll-off" grain in shadows and highlights.

  A quick way to do this is to use something like the Color Range tool to select the highlights and the shadows for separate layers.

  A better solution is to use the layer Blend If settings to restrict where grain gets applied. The Blend If sliders allow you to refine where grain is apparent in a photograph and do it with great precision.

• Working with Channels. Applying noise reduction to a single layer is going to be less effective than working with individual channels. The Amount setting should be highest for the Blue channel, lowest for the Red channel, with the Green channel somewhere in between.

Modifying the Film Grain Effect

Photoshop CS3/CS4 add support for Smart Filters. If you own Photoshop CS3/CS4, you should use Smart Filters for film grain effects. The settings should be adjusted for best visual effect.

Another reason for using Smart Filters is that you can apply the film grain effect with separate settings for Lighten and Darken blends and then wrap that up inside a Luminosity blend for the entire Smart Filters layer.

The appearance of the film grain can be affected in a number of ways:

• Use Gaussian Blur to soften grain.
• Use Sharpen, Sharpen More, Unsharp Mask, etc. to make grain appear more distinct.
• Use Curves, Levels, Shadows/Highlights, etc. to affect the contrast of the noise.
• Use Threshold to adjust the grain pattern.

OK. I'm going to stop here and hope we can have a discussion about the specifics for implementing these ideas.

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