Film Grain

From OSP Wiki

This tutorial was last tested for the Gimp 2.2.13

This script is based on the technique described by the GIMPGuru on this tutorial.

Overview

Sometimes you want that gritty, art-house/street-photography/high-ISO grainy film look, especially in monochromatic photos, this tutorial describes how each adjustment variable effects the final image.
Here is the original photo by Louise next to the photo with the Film Grain effect applied.

Original	Final

The original photo on the left than can be viewed here.

Prerequisites

You need to install the Film Grain script from the GIMP registry. (this is the old registry and the script needs to be uploaded to the new one)

For instructions on how to install the script read the GIMP scripts page.

Steps

First I will describe what the script does and then describe how adjusting the variables changes the result. Here is what the dialog box looks like and the steps the script does to the image

1. Adds a new layer in "Overlay" mode and fills it with middle grey.
2. Runs the "Scatter HSV" plugin on the grey layer with the vaules:
   • Holdness: 2
   • Hue: 3
   • Saturation: 10
   • Value: "Grain size" value from the dialog box
3. Runs a Gausian Blur with the "Blur Amount" value from the dialog box
4. If the "Add a layer mask" is ticked it also does the following steps as well:
   1. Adds a layer mask to the "Film Noise" layer.
   2. Copies the original layer
   3. Pastes the image into the layer mask
   4. Adjusts the curve of the layer mask, the height of red square is the "Midpoint adjustment" value of the dialog box

      

How the values effect the final image

1. Grain size: This is the value that the scatter HSV plug-in uses, the larger the number the larger the appearance of the "grains".
2. Blur amount: The grains are Gausian blurred by this amount smoothing them out some, if this value is too large the "grains" will disappear.
3. Add a layer mask: Normally, film grain tends to be most noticable in the midtones, and much less so in the shadows and highlights. We can add a layer mask to control how the grain pattern is applied to the image to accomodate this observation.
4. Midpoint adjustment: If you're grain seems too subdued, you may want to increase the Midpoint value up a bit to raise the brightness of the midtones in the layer mask.

Tips

1. You can combine the several effects together and produce images such as this on that combines Split toning

Split tone only	Combo

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