Chroma Key Guide for FMX for Windows

FMX for Windows can remove a green, blue, or custom-colored physical backdrop from Live View, captured photos, and recorded video. The current chroma-key controls are under Global Settings > Camera > Chroma Key (Green/Blue Screen) and can be enabled independently for each output.

Good lighting and backdrop preparation matter more than aggressive software settings. Start with an evenly lit, saturated background, then use Auto Calibrate or the eyedropper before adjusting the edge controls.

Before You Start

• Stretch the backdrop so folds and shadows are minimized.
• Light the backdrop evenly from both sides.
• Keep the guest far enough from the backdrop to reduce colored spill.
• Avoid clothing or props that match the key color.
• Select and start the real event camera in FMX.
• Test at the same exposure, white balance, and resolution used during the event.

Choose Where Chroma Key Applies

Under Apply chroma key to, enable any combination of:

• Live View: Removes the backdrop from the real-time guest preview.
• Take Photo: Creates a keyed captured-photo result for the workflow and layout pipeline.
• Video: Keys recorded video using the recording background selected below.

These toggles are independent. For example, you can key the final photo without applying real-time keying to Live View, or key Live View and photos while leaving video unchanged.

Choose the Backdrop Mode

Green

Use for a conventional saturated green backdrop. Green is usually the easiest choice when guests are unlikely to wear green.

Blue

Use when green clothing, products, or branding are common. Blue backdrops often require more light than green.

Custom

Use a measured color from the live camera preview. Custom works best with a saturated, consistent backdrop, not white, gray, black, or a low-saturation wall.

Calibrate the Key Color

Auto Calibrate

1. Start the camera preview with the guest area empty.
2. Make sure the backdrop fills most of the frame.
3. Click Auto Calibrate.
4. Wait for FMX to analyze the unkeyed frame.
5. Review the reported key color, suggested strength, and backdrop coverage.

Auto Calibrate can reject a scene when the backdrop is not saturated enough, several strong colors compete, or the frame does not contain enough usable backdrop.

Eyedropper

1. Click the eyedropper control.
2. Click a representative part of the displayed backdrop inside the camera image.
3. FMX switches to or updates the Custom key color.
4. Sample a mid-tone area rather than the darkest shadow or brightest reflection.

If the backdrop varies, improve the lighting before trying to average the problem with stronger settings.

Adjustment Controls

Strength

Controls how closely a pixel must match the selected backdrop before it becomes transparent.

• Increase when backdrop patches remain visible.
• Decrease when skin, clothing, or props begin disappearing.

Edge Softness

Creates a smoother transparency transition around hair, fabric, and object edges.

• Increase for harsh, jagged edges.
• Reduce when the subject looks blurred or surrounded by a soft haze.

Spill Removal

Reduces reflected green or blue color on skin, hair, and clothing.

• Increase when colored halos remain.
• Reduce when natural colors become gray or desaturated.

Edge Choke

Pulls the visible edge slightly inward to remove a remaining colored outline.

• Use small changes.
• Too much choke removes hair detail and narrows fine objects.

Photo Refinement

Enables a higher-quality matte refinement for captured photos. It can improve hair and edge quality but adds processing work.

Use it for printed still photos after testing the processing delay on the booth computer. Live View uses the real-time keyer and does not wait for full photo refinement.

Configure a Recording Background

When Video chroma keying is enabled:

1. Click Browse under Recording background.
2. Select a supported image or MP4 video.
3. Run a short Record Video workflow.
4. Confirm framing, aspect ratio, loop/playback behavior, and final video output.

The recording background is used for keyed video. Photo backgrounds normally come from the active photo layout and its background elements.

Clearing the recording background removes that selected replacement; test the resulting video behavior before the event.

Recommended Setup Order

1. Lock camera exposure and white balance.
2. Light and frame the empty backdrop.
3. Select Green, Blue, or Custom.
4. Run Auto Calibrate or use the eyedropper.
5. Add a subject at the real standing position.
6. Adjust Strength only as much as necessary.
7. Add Edge Softness, Spill Removal, and a small Edge Choke if needed.
8. Enable Photo Refinement and compare a full-resolution capture.
9. Choose a recording background if video is used.
10. Test Live View, Take Photo, and Video separately.
11. Click Save Changes.

Use Reset chroma settings to restore the defaults for the current backdrop mode when tuning becomes difficult to diagnose.

Test the Complete Workflow

• Live View shows stable real-time edges without excessive flicker.
• The captured Raw/processed photo retains hair, hands, translucent items, and props.
• The Final Photo layout uses the intended background.
• Recorded video contains the selected replacement background and remains synchronized.
• A guest wearing colors near the backdrop color is still visible.
• Settings survive closing and reopening Global Settings after Save Changes.

Troubleshooting

The subject becomes transparent

• Lower Strength.
• Re-sample the actual backdrop color.
• Move the subject farther from the backdrop.
• Avoid clothing that matches the key color.

Backdrop patches remain

• Improve backdrop lighting and remove wrinkles.
• Run Auto Calibrate with the scene empty.
• Increase Strength gradually.
• Sample a representative mid-tone with the eyedropper.

Green or blue halos remain

• Increase Spill Removal gradually.
• Add a small Edge Choke.
• Increase subject/backdrop distance.
• Add a neutral back or hair light.

Hair edges look jagged

Increase Edge Softness slightly and enable Photo Refinement for still photos. Avoid raising Strength so far that fine hair disappears.

Auto Calibrate fails

• Make sure the backdrop fills most of the empty frame.
• Increase saturation and lighting uniformity.
• Remove people and brightly colored objects.
• Use the eyedropper when a valid saturated backdrop is present but automatic analysis remains ambiguous.

Live View is keyed, but photos are not

Enable Take Photo under Apply chroma key to, save settings, and run a new capture.

Photos are keyed, but recorded video is not

Enable Video, select a recording background, and start a new recording. Existing videos are not retroactively changed.

Video uses the wrong background

Re-select the file under Recording background and test with the same orientation and aspect ratio as the final event.

For choosing between physical chroma and AI removal, see Green Screen vs. AI Background Removal.