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Learn how to composite Cycles render passes in Blender for utmost control of your scene.
http://cgcookie.com/blender/2012/12/10/compositing-cycles-render-passes-blender/

In this tutorial we will look at how to use the individual render passes for Cycles to manually composite our render together. The render passes represent each of the components that make up the final image, including diffuse color, diffuse bounce lighting, glossy reflection, etc. By using the render passes to composite the render together we gain utmost control over each aspect of our image, allowing us to modify or fix areas in composting that otherwise would require a new render.

Using a product render as an example, you will learn how to properly composite each of the render passes together from Cycles to get the final image. You will learn how to reduce noise on the individual passes that cause the noise, how to use the UV pass to replace textures in compositing, and you will learn how to remove fireflies from the render.

To learn more about compositing and how you can use it to gain absolute control of your renders, check out Bartek’s Blender training series:
https://cgcookie.com/products-page/blender-training-series-categories/compositing-in-blender-2/

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