The Vortex Media WarmCards are a white balance reference system for improving overall image quality. For all their sophistication, today's digital video cameras can have trouble telling the difference between indoor lighting, a rainy day outside, and the bright sun. In some cases, the differences can be significant. Bright daylight tends to look blue, incandescent lighting looks yellow, and fluorescent lighting looks green. The human eye adapts very quickly to the color temperature variations in these light sources so the differences are nearly imperceptible, but your camera isn't that smart.
In wedding videography and other work where humans are the principle subjects, a true white balance using a gray/white card will not deliver pleasing skin tones. A "warmer" white balance is usually what customers and clients prefer, and using WarmCards to customize the color balance of your camera is the perfect solution.
WarmCards are balance cards that appear slightly blue in their hue. This method tricks the white balance to a warmer matrix by balancing off colder (blue) cards. The added benefit of WarmCards is their high quality matte finish, which is both waterproof and specially coated to reduce glare. Turn them around and you have standard white balance cards that are extremely rugged. The unit comes with 3 small and 3 large cards in a convenient pouch for safe keeping. Green cards can be added to the set for balancing the effect of florescent lighting.