Chrome Key – Green Screens and Blue Screens
What is Chrome Key?
Chroma key is the process of video shooting on a solid color background and then digitally removing the background during editing/post-production process. Chroma key is also known as color separation and color keying overlay, and it is also commonly called green screens and blue screens. These screen sets are very common in filmmaking and television studios.
Click on Below Video: Post Production for Green Screen Chroma Key
Difference between Green Screens and Blue Screens
When it comes to green screens and blue screens, both screens are used for the same purpose: to use Chroma Key technology to place subjects in front of a projected background. During the process, editors can film characters and objects in front of a static background, remove the color of the background and replace it with a new background from the images. The green and blue colors are not present in human skin tones which makes them ideal for Chroma Key process as opposed to the color red.
Use of Green Screens
Not only is color essential when deciding which to use, but luminescence also plays a big factor. The green channel is the cleanest on digital cameras, and hence the sensors deliver less noise. Due to this, green screens are by far the most popular. Highly versatile, green screens work great for studio shoots, indoor or outdoor. And, because of their brightness, you will be able to get away with using fewer studio lights so you can save your time and money when shooting. A non-reflective surface that helps to creates a smooth, even backdrop such as the Tech Green Seamless Paper is an excellent choice for shooting in multiple places. Below we describe three key points about green screens:
The high key factor of the color tends to create bleed onto the subject. Be sure to light the scene evenly. It eliminates shadows and makes the keying process easier in post-production. Avoid wrinkles in photo backdrop as well as they do not key out properly.
Make sure the subjects you choose are not wearing any green colored wardrobe or the background you mask in will appear on their dresses.
3. Subject to Background Distance
Be sure to leave enough distances between subject and backdrop or you may experience from spillover as well.
Click on Below Video: Use Green Screen to Create Composites in Photoshop!
Use of Blue Screens
Blue screens are darker, and it works best with low light scenarios such as night scenes. For shooting, at night studio blue seamless paper screen are easy to set up and reusable to help save on those costly night location shoots. Below we describe three key points about blue screens:
Less spillover due to its low-luminosity.
2. Color Corrections
Somewhat more comfortable with blue screens (ex. Blonde hair quickly turns into brownish after removing green. Be careful, however – the camera samples blue less than green. It means that when setting your key, there may be considerably more tweaks and corrections for a smooth, natural key.
As with green screens, be wary not to include wardrobe the same color as your screen.
The blue key requires a whole f-stop, or two times more light. If you are lighting a large scene, this could show to be difficult.
Click on Below Video: Blue Screen vs Green Screen: Which should you Use?
Learn how to Master Green Screens and Blue Screens
Practice in various locations and vary the lighting, wardrobe and props to see what effects you obtain. Import your test shots into Photoshop and open Channel/Windows. Select either the green or blue channel only (depending on what screen color you have chosen). It will allow you to evaluate the luminance factor of any green or blue objects in the scene and determine if enough separation is achieved. Keep a diary of each set-up you create for future reference.
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