While recently doing a video shoot, I was drawn into an argument on which screen, between the blue-screen and the green screen, works best. Is there any difference between the blue backgrounds, and the green ones? Does the choice of screen color affect the chroma keys? Here’s the definitive answer to all those questions.
Green Screen Vs Blue screen: Which one should you choose? In digital shoots, the videographers prefer the green screen over the blue screen. On most occasions, the notion that the foreground subject has a lesser chance of wearing green clothes informs this. Besides that, the green screen also reacts better to lighting than blue screens do. In addition, digital cameras produce cleaner images on the green screen. This is because green has the highest luminance between digital colors available.
Most videographers often come across the difficulty in choosing what color should be used for chroma keying. In the past, blue was often the preferred color. Blue screen reigned supreme in action scenes. But the green screens seem to have taken over the field.
What makes the green screen triumph over the blue screen?
When compared to blue screens, color sub-sampling using the green screen is a walk in the park. A video’s pixels are split into three values. One value defines the luminance of the film, the other two pertain to the color in the video. When doing color sampling, the intention of the producer is to split the value into independent pieces that can be blended together with other backgrounds.
Green is the farthest color in the spectrum of human vision. Camera’s ride on pretty much the same principle. Therefore, it is significantly easier to string out green from a range of colors, than it is to remove blue from the same range.
Blue screen poses significant challenges in color sampling. The physical shoot might go on seamlessly on the blue screen, but removing the blue background completely comes with its fair share of challenges. Besides being a color that blends in with the mid-range colors in the camera sample, blue also forms shadows on the subject if not lit well enough.
Most cameras also sample blue on more occasions than they sample any variance of green. This means that blue is more likely to appear in your footage than green would at any point. It also means that the camera needs less sensitivity and tweaking to record subjects shoot on green screens.
How many times have you seen an actor don a green suit? A completely green suit? How many times do we see clothes that are made of shades of green in videos? I bet they are only a few.
Here’s the deal. There is a very low probability that the person you intend to shoot will turn up in green clothes. On the other hand, blue is a day-to-day color for clothes. Everyone has a blue shirt, a blue suit, a blue dress somewhere in their wardrobes. You can’t risk having a blue screen when blue is right next to black on the list of colors that make everyday clothes, can you?
Aside from the low chance of a subject actually wearing something green, the green screens also provide striking contrasts with the most range of colors. Because it is the last in the range of colors that the human eye can see, it’s relationship to any other colors is by far a divided by huge spaces occupied by other colors. It does not blend in, or form hedges as blue would.
Blue was the color of choice for making green screens when the negative film was the king of storing footage. How many years back was that? With physical film negatives, blue was easy to clean out. It was also easily visible among all the colors in the film.
Using blue was based on the fact that blue is the farthest color on the spectrum from red. The human skin is defined by red on most occasions. Using blue provided minimal interference on the footage or spillovers. Moreover, blue was preferred because the color sub-samples in the cameras of the day had a dalliance with blue screens. The final footage, shot on film, had way less noise than on any other type of screens.
But times change. Digital cameras have completely wiped out the prevalence of films in video shooting. Unlike film cameras, digital cameras are set to adapt to green screens more than they would to blue screens. That is just the fact of the day.
Digital cameras work process colors based on the Bayer processing system. Bayer processing means that the camera is set to a filter arrangement that shoots more green pixels than either red or blue ones. In fact, a DSLR digital camera shoots double the number of green pixels per each blue pixel. The end resolution of the green will be double that of either red or blue in the video. Simply, the green will contrast more. It will shout while the other colors will only whisper.
Since the cameras are firmly grounded in a romance with green screens, it is only fair that you adapt to what the camera can easily shoot. Besides, it also means that you will have to undertake way less tweaking of the camera settings and aperture exposure to get the quality of footage that you desire.
Cleanliness of the final footage
With screens, the quality of the video is valued on the noise levels of the said video. We are not referring to physical noise here. It is nothing that your ear can pick. In fact, the statement ‘noise level’ is in no way related to any external noise that is likely to affect the audio quality of your video.
The noise level refers to subtle changes that only your eyes can pick in a video. The human eyes are the benchmark for great lenses. Any slight changes or interruptions in lighting, views, coloration will be noticed by the human eye. The higher the amount of changes, the higher the visual noise levels of the video. The intentions of any video producer when using screens in a shoot is to keep the noise levels as low as possible.
The noise levels can also refer to the audio. Blue screens have a higher amount of audio interference compared to the green screen. The green channel also has the highest level of cleanliness in all the camera channels. It is almost sterile-clean. Given it is already squeaky clean, the sensors do not have to squeak out in during the shoot or to adjust themselves to clean the noise.
However, it is a proven fact that blue screens have significantly higher nose levels than green screens. This means that keeping the noise low on the blue screen poses a bigger challenge than it would on the green screen. Since the noise can only be reduced during composing, it also means that you, as the producer, will have a larger amount of work to do in editing.
Green screens are highly luminous. In fact, green reflects a large amount of light. Blue screens, on the other hand, seem to have a relationship with black. Since it is darker, it will absorb the light shed onto it. This implies that you need more lighting to shoot on blue screens than you do to complete a good shot on a green screen.
The blue screen needs double the light that the green screen uses. It means you have to invest in more lighting if you are going blue. In addition, lighting a large blue screen is also a challenge for most videographers. How do you balance lighting on a large screen that absorbs most of the light you cast on it?
You can produce decent video footage on the green screen without using complicated lighting setups. A blue screen will force you to dig into your bag of lighting tricks, just to get a half decent video footage.
Ease in capturing complex backgrounds
The final stage in shooting on either the green or blue screens is chroma keying. Here’s the deal, it is way easier to insert complex backgrounds on videos shot on a green background than it is to insert the same on footage based on a blue screen.
Most video backgrounds come in shades of dark colors. Since the footage from the green screen is luminous, the subject will appear more luminous on the darker backgrounds.
Are there situations where blue screens are preferred over the green screens?
Unfortunately, the green screen doesn’t win everything. In some special situations, you would rather use the blue screen over the green one.
What are these situations?
When you shoot a brightly colored subject on a green screen, you might notice streaks of green on the subject during chroma keying. For instance, if you shoot a lady with long blonde hair, the green color will ‘stick’ on her hair. This remains of the background color are called spillovers.
One thing about spillovers is that they are hard to edit out. The haunting ‘ green glow’ will haunt the whole of your video if are not careful. You might end up tarnishing the whole video while trying to edit out a single streak of green. The green also spills onto the edges of the subject, if they are dressed in clothes that reflect the luminous nature of the screen.
To avoid this, using blue screens is sometimes called for. Blue has less luminosity. The light won’t bounce off the screen onto the subject. Using the blue screen means that your video will have minimal if not zero spillover issues.
It’s pretty hard to do tangible color corrections on the green screen. Given the camera samples more blue than green, it is easier to correct the color on a footage shot on a blue screen than it is to do the same on a green screen. This is because the color will appear more frequently on the footage.
Correcting off-colors on the blue screen is also easier. On the green screen, off-color correction might cause messy footages with a lot of smothered edges. This might just eat up your whole day, on editing. No videographer wants to spend so much time correcting colors.
Foreground color conflicts
What do you do when your subject is dressed in green? What screen do you use when you have to shoot a scene where the actors are in some form of camouflage gear? All these are typical examples of foreground color conflicts that might pop up in the process of shooting a video on any screen. In all these situations, the obvious options would be to ditch the green screen for a blue one.
Some colors clash with green screens. Those colors that are any shade of green, from light to apple green will not be visible on a green screen. If you do a sample shoot with such colors on a man, you will only differentiate his head and places where his skin is exposed. Unless you are shooting for a torso-less video, you need a blue screen to achieve the contrast and avoid foreground color conflicts.
Foreground color conflicts, when ignored, are hard to edit out. They are the main reason for messy videos. Videographers spend a long time trying to solve the color issues that they mess up the whole video. Rather than go through this, you would rather use a blue screen from the start.
Outdoor and night shooting
The luminous nature of green makes it highly disadvantageous for outdoor and night shoots.
For the outdoors, it means that you will have to contend with the presence of plant green. If the plant green won’t be a nuisance to your shoot, the lighting might be. The rays of the sun on the green background produces a lot of reflections, and glare if the screen is not placed well.
Most producers prefer blue screens when they have to do a shoot in the dark. Aside from the fact that you need double the lighting, blue screens offer more contrast in the dark than the green screens.
Green is more composed when you are shooting during the day, or indoors where the lighting can be controlled to fit the ISO you need. Any leftover green in the day can blend into the glaring natural light. However, in the dark, the situation turns in favor of its blue counterpart.
Apart from green and blue, what other colors can make a screen?
While videographers often prefer blue or green in creating screens, practically any color can make a good screen. So long as the color contrasts with the subject’s clothing and appearance, it is good to form a background.
A good number of movies have been shot on red screens. I have seen that at work. Red comes into the mix of screen colors when the producer feels there is a need to have more vibrancy. Just like red, most other colors have the propensity to clash heavily with the object’s coloration. The skin, for instance, would pose a huge challenge to a red screen.
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