In the last few decades, visual entertainment has gone from being just an art and just a source of entertainment to a multibillion dollar industry. We are often left wondering how movie makers and actors manage to film perfectly coordinated and timed scenes in exotic locations. Where are these scenic locations and how much does it cost to fly the cast and crew to film an action sequence set in a jungle? The simple and cost effective answer to those questions is a green screen. How does a green screen work? A solid green (or sometimes blue) backdrop is place behind the actors, newscasters or weather correspondents who then act out their scenes during filming. Later, the green background is made transparent and replaced with a desired clip digitally in the editing stage. This process is technically called "Chroma key".
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Scenes that require significant movement, like driving, rapidly changing backgrounds, special effects like flying in the air or floating in the air or mostly filmed using this technique. A green screen is a cost effective, efficient method that allows filming to be done in the comfort of a studio setting without having to compromise on the overall effect that the producer and director are trying to achieve.
How to make a green screen?
Professionally, green screens are usually made of fabric or a solid material like wood or cardboard that has been painted green. It is fairly simple to make an inexpensive green screen at home that can be used for photography or filming. Before making one's own green screen it is imperative to understand the mechanism behind it. The color green is usually used because it is not commonly found in human skin or clothing, this makes it easier to separate and replace later.
1. DIY green screen-How to make a green screen on a tight budget?
If you are on a tight budget and need a green screen, you can use two easily available materials at the stationery and hardware stores that cost almost nothing and assemble it yourself. You will need about eight to ten (depending on the size) sheets of bright fluorescent, neon green chart paper/ poster board and duct tape in the same color. Both of these can be found easily at your local supply store. Using the duct tape, paste the poster board on an empty wall till the entire wall is covered. Typically, you will need to paste two sheets horizontally to create the ideal width and the rest can be stuck vertically. Make sure to extend the poster board past the wall and on to the floor so that the actors can stand on it while they film. This method will give you a fast, cheap green screen which can be built indoors or outdoors and has little assembly time. When this screen is used with a good quality Chroma key software, the results are almost professional looking.
2. DIY green screen-How to make a portable green screen?
In case you need to move your green screen around, the above method is probably not the most suitable way to go. You can also assemble your own portable green screen kit. This method also uses florescent, bright neon green poster board sheets but they are stuck on to foam core boards instead of walls. Foam core boards are a lightweight and portable alternative to walls making this green screen cheap but efficient. Start by pasting the poster board on to a panel of foam core board each. You can use liquid glue or a spray on adhesive to do this. It takes about six such panels to make a complete green screen but the number can be altered depending on your requirements and the size of the poster board and foam core boards. The next step is to create two longer panels that can also fold up for mobility. To do this, attach two foam core boards to each other using duct tape on the non-poster board side. You will need two of these so four panels will be used. Leave the remaining two separate and unattached. When you need to assemble the green screen, attach the two larger panels to each other using hook and eye tape. Adding sturdy rectangular pieces of foam or lightweight wood at the junctions will support the complete, larger panel and help it stand upright.
How to use a green screen
The next step is to use appropriate lighting to brighten the screen. If you are using overhead lighting, ensure they are directly above the subject and the lampshades have been removed. Adding a spotlight outside the green screen area and placing it between the subject and the screen is a good idea as it prevents a shadow from being cast on the screen while illuminating it. About three feet away from the screen and behind the subject, use a magenta colored light. This can be made by coloring an amber light bulb magenta with a permanent marker. Use another magenta light four feet away from the screen and directly above the subject. Using magenta lights will help reduce the amount of green light reflected off the subject's skin and props.
Knowing how to make and use a green screen, we still need to remember some tips when using a green screen can give you better and more professional looking results. According to some professionals, key to a good green screen is using the right shade of green. Mostly bright, saturated green shades are preferred over darker and less saturated shades. If the screen is being made with a fabric, it must be smooth and made of a non-reflective material. Another important factor is lighting, typically two or four studio lights are used. If you are making your own spotlights in addition to overhead lighting, use high intensity bulbs (300-500 watts). It is a good idea to add place a filter in front of these lights, for instance one made of coffee filters or wax paper. This will help diffuse the light evenly before it hits the screen. The lights should be placed at 45 degree angles to the green screen. If you find this lighting to be insufficient, adding two more lights on either side of the screen can help brighten up the place. Typically these can be lower intensity bulbs (around 200 watts each). The use of magenta lights, like in the DIY tutorial above can help counteract the green reflection on the skin and surface of props. Making the subject stand at least six feet from the screen will also reduce the reflection but this may not always be possible.
What else do you need to make the green screen work?
To make the green screen work well, using a good quality camera that shoots HD quality video is advised. However, any camera that shoots videos in MP4 and MOV formats will work, including phone cameras. You will also need a good quality Chroma key software, many are available on the market and some can even be downloaded for free. Some software include Windows Movie Make 2.0, Movavi and Final Cut. However, consumer grade software have lower grade Chroma key effects. For still photographs, Adobe Photoshop has a built in Chroma key feature that allows users to manipulate photographs taken with a green background by changing it to whatever they would like. Many software comes with Chroma key backgrounds, others can be downloaded separately.
I personally use and highly recommend Wondershare Filmora to you, for non-professional use.
Wondershare Filmora (originally Wondershare Video Editor)
- Supports virtually any video formats you shoot.
- Easily chroma key the background of your video.
- Seamlessly blend your video with new backgrounds.
- Different methods to share your video with the world.
Check the Video Tutorial: How to Make a Green Screen Video