We all know what green screens are, but what about blue screens? Let's further explore when someone should use a blue screen vs. a green screen for production.
When to Use a Blue Screen
Foreground Color Conflicts
The first and most obvious reason you want to use a blue screen vs. a green screen is if your foreground object / subject is green or is wearing green. Solid green colors, green gradients, green patterns, and even camouflage can interfere with green screen capture. Always use a high-contrast foreground / background color combination for best capture results.
Both green screens and blue screens have what is known as Color Spill which can change your image color balance. Color spill is the color that reflects onto and/or bleeds into your foreground subject. Chromakey green can produce undesirable "green screen glow" or fuzzy/feathered edges in some capture scenarios. A blue screen can be a great alternative as the green glow becomes a blue glow which is an easier color adjustment to make. Additionally, a chroma blue background allows for a more well-rounded color profile via most digital camera sensors.
Night Time / Twilight Scenes
For the exact same reason as above, a blue color spill is more natural and effective for night time, twilight, and dusk photography and video. If you are superimposing something into a darker scene, you will naturally want blue / darker color spill to help match and composite your footage layers.
Blue Screen Benefits
- Less Harsh Color Spill
- Better Color Balance
- Easier Color Correction
Blue Screen Capture Requires More Light
Chroma blue has lower luminosity and therefore requires double the light to make it as effective. Either increase your camera's F-stop or add additional studio lights.
When To Use A Green Screen
Complex Objects and Shapes
Chroma key green capture is twice as accurate as chroma key blue. If you have a complex object or shape, with lots of odd negative space / cut-outs, example: hair, a green screen background will do a better job at isolating the foreground from the background every time.
Less Post Production
More chroma key accuracy, means less post production work and hours of editing. When you need to work smarter, not harder, green is better!
Daytime Lighting / Outdoor Scenes
A green screen is a superior color choice to a blue screen when working daytime shoots and working in daylight. Again, this has to do somewhat with the color spill, but more importantly it is more luminous.
Green Screen Benefits
Green screens work best with digital cameras.
Green Color Channel Is The Cleanest of Noise
The green color channel is the cleanest channel in the RGB spectrum. It carries less pixel noise and light distortion because it has the highest luminance / light carrying capability of the three channels.
Many digital cameras are single-chip and use a Bayer Filter which records at 50% Green, 25% Red, and 25% Blue. Twice the green being recorded, means more green resolution and therefore more accuracy in the green channel. When photo and video professionals need the most accurate chroma key possible, they use chroma green backgrounds.
If you are using a 3CCD camera (3-Chip / 3-Sensor) then you can ignore this because you don't have a Bayer Filter. However, still remember GREEN is a superior color channel and therefore is usually a better solution for your 3CCD camera too.
Color Accuracy with Green Screen
The only minor concern with a green screen is the color spill mentioned previously. As an example a person with light brown or blonde hair tends to have their hair / highlights turn "red" because of the green background. Positioning the host further away from the green screen helps, but does not entirely solve this. While this is usually easily corrected in post production software, if RAW color values are most important for your project, consider a blue screen instead of green.
In almost every scenario, 95% of the time, chroma key green backdrops win. However, chroma key blue can be a clutch card to play when your green screen isn't working like it should.
If you have other chroma key questions, comments, or concerns, please contact us!