Adding Grain to a Composition

The Add Grain tool lets you sample the grain from one image (the reference image) and apply it to another image (the input image) or sequence. In the following example, a CG character is used as the input image and the mountain background is used as the reference image (the grain will be analyzed from this image).

(a) Input image of CG character on which grain will be applied.  (b) Panner tool to place the CG character at the desired location in the reference image.  (c) Add Grain tool  (d) Comp Ops tool to composite the CG character over the background(A over B).  (e) Reference image from which the grain is sampled.  

Once the dependency graph is built, you can decide which area of the reference image to sample. You can select samples from multiple areas of the image. You should use an area of the image that just contains grain, avoiding areas with image or edge detail. Once you have positioned the sample area, you can apply grain to the input image. After adding grain to the input image, you can manually adjust the response curves for the gain and size of the grain.

To add grain to a composition:

1. From the Tools tab, drag the Add Grain tool from the Grain Management folder to the dependency graph in the Schematic view.
2. Connect a reference image and an input image to the Add Grain tool.
3. (Optional) Add a mask to your input image to restrict the grain to a portion of the image—see Creating Masks.
4. In the Add Grain tab, do one of the following:
   • Click the Analyze button.

     Regions of the reference image that are appropriate for analysis are analyzed and grain is applied over the entire composition.

   • Click the Selection button and drag to define an area to analyze. For best results, define multiple regions of uniform color, avoiding areas that may resemble grain such as gravel, sand, or a forest. Click the Analyze button to create the grain. Click Clear to clear any areas you defined and start again.
   

   (a) Selection button  

   The regions you defined are analyzed and grain is applied over the entire composition. Response curves are generated and displayed in the Animation Editor. You can now fine-tune the resulting curves—see Fine-tuning the Grain.

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