If you're creating a Video Twibbon with an MP4 or WEBM file, your design needs a chroma key, also called a green screen. This article explains what that is, why it matters, and how to get it right.
What is a chroma key?
A chroma key is a solid block of one color in your video that marks the spot where something else should appear. It's the same trick used for TV weather maps. The presenter stands in front of a plain green wall, software erases every green pixel, and the map appears behind them.
In a Video Twibbon, that erased area is where your supporter's photo goes. Because the color is usually green, people also call this a green screen. Chroma key and green screen mean the same thing.
Why a Video Twibbon needs one
A Twibbon is a frame with a hole in it. The design surrounds the hole, and the supporter's photo shows through.
For still designs, the hole is easy. PNG and GIF files can store real transparency, so the hole is simply "nothing." Video works differently. MP4 and WEBM files have no transparency layer at all, so every pixel has to be some color.
A chroma key solves this. You fill the hole with a color you don't use anywhere else in the design. Twibbonize treats that color as the hole and removes it when the campaign runs.
Your file | How the hole is marked |
GIF | Real transparency — no chroma key needed |
MP4 or WEBM | A chroma key (solid green area) stands in for transparency |
How it works
You upload the video with its green area.
Twibbonize removes every pixel matching that green. The checkerboard pattern just represents "empty" — it isn't part of your design.
Your supporter's photo is placed behind the hole. The design stays on top, and the photo fills the gap.
Twibbonize keeps your original design intact and composites the supporter's photo behind it every time the campaign is viewed. That's why one Video Twibbon works for thousands of different supporter photos.
What Twibbonize detects automatically
When you upload an MP4 or WEBM, Twibbonize scans your video and looks for a green area. If it finds one, it:
Picks up the exact shade of green you used, so you don't have to type in a color code
Chooses the best frame for your campaign thumbnail, where the green area is largest
Lets you know if it can't find one — if your video has no green area, you'll see "No chroma key area detected in your video file," and the campaign can't accept supporter photos until you fix the file
A few stray green pixels, like a leaf or a logo highlight, won't be mistaken for a chroma key. The green area needs to cover a reasonable portion of the frame.
Green or blue?
Both colors work for chroma keying, but for Twibbonize, use green. Automatic detection looks for green, so a green screen means your upload just works.
Blue still functions, but you'll need to open Chroma Key after uploading and set the color yourself, using the color field or the eyedropper.
Whichever you pick, the key color can't appear anywhere else in your design. If your logo is the same green as your background, the logo will disappear along with the background.
How to prepare a good chroma key area
Twibbonize removes every pixel close enough to your key color, so a few things matter:
Use one flat, saturated color. A pure, bright green, in the range of #00CC00–#00FF00, works best. Pastel or muddy greens sit too close to skin tones and clothing.
Keep the color even. Avoid gradients, shadows, or a bright hotspot in the middle. An uneven patch may survive removal and show up as a green mark.
Give the area hard edges. Soft glows, drop shadows, motion blur, and semi-transparent edges create a thin fringe that's neither fully green nor fully design.
Don't reuse the key color in your artwork. Text, icons, borders, and logos all need a different color from the key.
Make the area big and well-placed. This is where the person appears, so a small key area means a small face. Portrait orientation, with the window in the upper-middle, usually works best.
Adjusting Strength
After uploading, click Chroma Key under the preview to open the key color and a Strength slider. Strength sets how tolerant the color match is:
Too low, and only near-perfect matches are removed, leaving a green rim or speckles around the window
Too high, and the match becomes loose enough to catch colors that only vaguely resemble the key, so parts of your design start to vanish, usually yellows, teals, and light greens first
Start with the value Twibbonize picked, then adjust in small steps. Stop as soon as the green disappears.
When to use a GIF instead
A transparent GIF is often simpler, since there's no color to match, no fringe, and no Strength slider to tune.
Choose GIF for simple animation, like a pulsing border or a rotating badge. Choose MP4 or WEBM for real video, with footage, gradients, many colors, or sound. Keep in mind that GIF is limited to 256 colors, so photographic or gradient-heavy designs look better as video with a chroma key.
Troubleshooting
What you see | Why | Fix |
"No chroma key area detected" | No green area found, or it's too small | Add a solid green block where the photo should appear |
Green rim around the photo | Match tolerance is too tight, or the green edges are blurred | Raise Strength slightly, and avoid feathering the green area's edges in your editor |
Parts of the design disappear | Tolerance is too loose, or design colors sit close to the key | Lower Strength, and recolor any design element close to the key color |
Green patches left in the middle | Uneven lighting or a gradient across the green | Re-export with one flat green fill |
Photo appears in the wrong place | The green area isn't where you expected | Move the green block in your design and re-upload |
Whole video vanishes | The key color was sampled from the design, not the green area | Reopen Chroma Key and re-pick the color with the eyedropper |
Frequently asked questions
Does my supporter see the green? No. The green only exists in your source file. Everyone viewing or joining the campaign sees the finished composite.
Can I have more than one photo area? Not in one design. A single key color defines a single hole, however oddly shaped. You can upload several video designs to a campaign and let supporters choose between them.
Does the green area have to be a rectangle? No. Any shape works, including circles, hearts, phone outlines, or cut-out lettering.
Can the green area move or change size during the animation? Yes. Removal is applied to every frame, so a window that slides, grows, or spins still works.
What if I don't have video editing software? Most free editors, like CapCut, Canva, or DaVinci Resolve, can place a solid-color rectangle over a design and export it as MP4. You only need a flat color block.
We hope this helps you prepare a clean chroma key for your Video Twibbon. For step-by-step upload instructions, see How do I create a Video Twibbon campaign?