Green screen best practices

Overview


You don't need a green screen to use mmhmm, but using one can give you more options for controlling how you look on screen. Here is what you need to do to get started using a green screen with mmhmm and some tips to enhance your image quality on-screen.

Table of contents

Green screen types and settings

You can use two types of green screens with mmhmm: virtual or physical. The virtual green screen is included with mmhmm and requires no special setup. It automatically detects the position of your head and body in the foreground and separates it from your background, allowing you to take advantage of mmhmm's rooms, or backgrounds.

Physical green screens are usually made of green fabric and hung from a stand or frame in your physical environment. Frequently used in Hollywood and online streaming, the bright green of these backdrops makes it easier to digitally superimpose the subject in a virtual scene.  While these require a bit more effort to acquire and set up, they are currently the best way to make the subject "pop" in a virtual room. You can change select your greenscreen type in your camera settings, found in the top right corner of mmhmm.

The default is the virtual green screen, but if you have a physical green screen, select "I have a green screen".
 
mmhmm for Mac mmhmm for Windows
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Setup

1. Click on the Camera settings dropdown on the top right-hand side of the mmhmm window. Select the box for “I have a green screen,” and choose the color that most closely represents your green or blue screen. Otherwise, you can also choose the chroma key color wheel to dial in the exact shade of your background.

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2. "Threshold" allows you to dictate the sensitivity of green screen detection so it recognizes the darker and lighter areas. Using the threshold sliders, adjust the range of hues that match your background. Experiment with the upper and lower bounds until you have a crisp silhouette.

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Lighting your foreground

The existing lighting in your room should be sufficient for mmhmm, but lighting your face with other sources of light can go a long way in improving the quality of your broadcast. 

Generally speaking, studio lighting concepts translate well to mmhmm. Here are some of those for you to consider for your own setup.

  • Ideal studio lighting illuminates a subject with soft, diffuse lighting from multiple angles to eliminate hard shadows. 
  • In a typical three-point lighting setup, the main source of light, or the key light, is set at an angle to one side of the subject. A second, softer light, called the fill light, is used on the other side of the subject to fill in the shadow caused by the key light. The larger the difference in light intensity between the key and fill light, the greater the shadow. ThreePointLighitng.png
  • A third light is sometimes used to light the subject's hair and shoulders from behind. This enhances a subject's silhouette and can make them stand out from the backdrop/green screen even better.
  • Fabrics are placed over the lights to diffuse the light. By increasing the surface area of the light source, the light is "softened," creating a more flattering lighting effect. To achieve this diffusion effect, studio lights are placed in softboxes or bounced off silver-coated umbrellas or through white, translucent umbrellas. 

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Even without professional studio equipment, these concepts can be used to combine the natural and artificial lighting in your environment to replicate these effects. Even something as simple as a desk lamp bounced off the cover of a book can be used to greatly enhance the lighting quality of your broadcast. 

If you are looking for a light, consider the Elgato Key Light Air.

My shoulders and hair have a green outline when I use a physical green screen, what should I do?

This is called green screen spill, and can be mitigated by adjusting the following:

  • Consider shining more light on yourself, as opposed to the green screen behind you. 
  • Adjust the chroma key color (see Setup).
  • Adjust the green screen threshold while working with the lighting.
  • use the Zoom slider (Camera > Zoom) to crop your image if you have a smaller frame to work with. 

 

Don’t see the answer to your question? If you’re having technical difficulties or want to suggest a topic for this guide, click here to submit a request or email us at help@mmhmm.app.

 

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