Elle Kyle, Writer, Producer at AMC
When working with a Green Screen, proper lighting is absolutely essential. Bad lighting is an immediate giveaway and calls negative attention your project. There are several factors to consider when lighting it to ensure the final product looks authentic.
Even Lighting
The shadow on this Green Screen increases the color range for the Chroma Key software to filter out and may interfere with the subject’s grey shirt.
When lighting a Green Screen, one of the most important considerations is to light it evenly. Consistent lighting helps maintain a consistent color across the backdrop. This, in turn, makes it easier for the Chroma Key software to map.
Essentially, it works by selecting a designated portion of the visible light spectrum and replacing subjects in that range with a transparent fill. The transparent sections of the picture can then be replaced with the desired background image.
When a Green Screen is not lit evenly, the camera picks up a wide range of colors on it. This means that the Chroma Key software has to filter out those colors, increasing the chance of keying out parts of the desired subject. Even, consistent, lighting diminishes errors in post-production.
Avoiding Light Byproducts
Even with a black curtain to dampen the reflection, spill can still be seen on the subject’s neck and upper arm.
Another challenge that lighting a Green Screen presents is dealing with the byproducts, if you will, of light: namely shadows and reflections.
It is important to light the subject in such a way that shadowing, as such, is reduced to a minimum. The problem that shadows present is much the same as that posed by uneven lighting. A shadow drastically alters the range of color that will be filtered, making it more likely that parts of the subject are unintentionally keyed out.
Reflections off the Green Screen pose different challenges. Given that the color green has a high luminance value, a Green Screen reflects light much more intensely than say, a Blue Screen.
This creates a problem when the green light reflects onto the subject. Unless your subject is in the light of a lime green object or has parts of it missing in the finished product, this reflection, called spill, is a dead giveaway. Placing black screens off camera helps absorb the light, reducing the spill effect.
Matching Lighting to Background Footage
Matching the lighting of the subject to the lighting of the background is imperative if the finished shot is to be convincing.
This can be done, to a varying extent, in post-production. Clearly, the caliber of your Chroma Key software is worth noting. The extra effort during production is worthwhile, as it creates a more authentic blend of footage.
Important factors to consider include: saturation, temperature, exposure, and the source of light in the background footage. Any inconsistency between the lighting of the subject and background will immediately alert a savvy audience to the use of a Green Screen. Although good lighting is not the only element that makes a good Green Screen scene, it is conducive to the best outcome one can envision and reach. All in all, good lighting makes a discernible difference in the final footage.
Taking the time to properly light your Green Screen pays large dividends in the end. It is well worth the effort.
