Here's a tutorial I posted a while back, but it's still very useful today:
Creating areas of light and shadow are no problem with DaVinci Resolve. PowerWindows, polygons, or curves can be a colorist's best friend when controlling where you want areas of contrast. The only thing that limits you is the simplicity of the shapes.
When shooting on set, a pattern or "gobo" can be placed in front of a light source to create shapes. We can use the same technique in Resolve by using external mattes. In this tutorial I will show how to create more intricate shadows or highlights that can make your images more moody or suggest location.
Directory of Gam Patterns: bit.ly/gampatterns
Images used in this tutorial: bit.ly/noirpatterns
image courtesy of Marta Colpani: flickr.com/photos/martacolpani/4934952722/
Noir Shadows and Highlights with DaVinci Resolve-HD.mp4