Yellow screen
Display a pure yellow screen to test red+green sub-pixel combinations and use as a warm photography light. Detects cross-channel pixel defects.
What a yellow screen reveals
A pure yellow at #FFFF00 drives the red and green sub-pixels to maximum while leaving blue completely off. Yellow is a secondary color in the RGB additive model — it's the sum of red and green, with no blue contribution. This makes the yellow screen a powerful diagnostic for sub-pixel combination behavior that single-color tests can't reveal.
If a pixel defect shows up on red and green individually but not on yellow, the defect is purely additive — both sub-pixels fire correctly when commanded together. If a defect shows up on yellow but not on red or green alone, you've found a cross-channel addressing issue. This is rare but real, and only the yellow screen surfaces it.
Red+green sub-pixel combo
Drives red and green together at maximum. Defects that only manifest when both channels fire together — invisible on red or green alone — appear here.
Warm photography light
Yellow at 60% brightness makes a warm key light for portraits, product shots, or video calls — flattering for skin tones without the harshness of pure white.
Blue-channel cross-check
Compare yellow (red+green) against red+green+blue = white. Any difference in uniformity or tint between yellow and white isolates blue-channel behavior.
Sub-pixel combination map for color screens
Each solid color screen drives a specific combination of sub-pixel channels. Understanding the combination map helps you choose the right pattern to isolate specific defects — and explains why all 10 colors are needed for complete coverage.
| Screen color | Red | Green | Blue | What it tests |
|---|---|---|---|---|
| White | 100% | 100% | 100% | All channels at peak — uniformity and tint |
| Yellow | 100% | 100% | 0% | Red+green combo without blue |
| Cyan (not available) | 0% | 100% | 100% | Green+blue combo without red |
| Magenta / Pink | 100% | 0% | 100% | Red+blue combo without green |
| Red | 100% | 0% | 0% | Red sub-pixel isolation |
| Green | 0% | 100% | 0% | Green sub-pixel isolation |
| Blue | 0% | 0% | 100% | Blue sub-pixel isolation |
How to use yellow for combo-sub-pixel testing
- 1
Start with red and green individually
Run the red screen and the green screen first. Note any defects you find — their locations will tell you what to expect on yellow. A pixel that's defective on red OR green will also be defective on yellow.
- 2
Display yellow fullscreen at 100% brightness
Click the yellow block above to enter fullscreen. Yellow at 100% drives red and green sub-pixels to maximum, so any cross-channel addressing issue will be maximally visible.
- 3
Compare defects found on yellow vs red+green
If you find a defect on yellow that wasn't visible on red or green alone, you've discovered a cross-channel addressing fault — rare but real. Document the location and check if it appears in normal content.
- 4
Cross-check with white to isolate blue
Switch to white (red+green+blue). Any uniformity difference between yellow and white isolates the blue channel's contribution — useful for diagnosing blue-channel-specific issues.
Beyond testing: yellow as a warm photography light
The yellow screen's secondary use is as a warm photography light. At 60–80% brightness, a fullscreen yellow produces a soft, warm key light that's more flattering for skin tones than cool white. Many streamers and content creators use yellow or amber monitor light as a budget alternative to a dedicated warm key light, especially for video calls where a separate light would be impractical.
The color temperature of #FFFF00 is approximately 2700K — slightly warmer than a traditional incandescent bulb (2800K) and noticeably warmer than warm-white LED bulbs (3000K). This makes yellow ideal for evening video calls where you want to look warm and natural without blasting yourself with cool monitor light that suppresses melatonin.
For technical testing, the yellow screen fills a specific gap in the sub-pixel isolation toolkit. The three primary colors (red, green, blue) catch single-channel defects. The three secondary colors (yellow = R+G, cyan = G+B, magenta = R+B) catch two-channel combination defects. White (R+G+B) catches all-channel issues. Together, these 7 patterns cover every possible sub-pixel failure mode. Our toolkit includes yellow, pink (magenta), and the three primaries — for a deeper dive on color mixing and gamut, see the [color gamut test](/color-gamut-test) and our [color science guide](/blog/color-science-explained).
Tips for yellow screen testing and use
- For warm portrait lighting: set yellow to 60% brightness and position the monitor at 45° to your face — this mimics a soft warm key light.
- For combo-sub-pixel diagnostics: always run red and green individually first, then yellow — the comparison is what reveals cross-channel faults.
- For evening video calls: switch from white to yellow as your key light to reduce blue exposure and look warmer on camera.
- For burn-in cross-check on OLED: yellow can reveal red+green emitter wear that white might mask due to blue overdrive — useful as a secondary burn-in diagnostic.
- Avoid using yellow at 100% brightness for extended periods — the high red+green output can cause temporary image retention on some OLED panels.
Yellow screen — common questions
Pair the yellow screen with these tests
Red Screen
Isolates the red sub-pixel — run before yellow to establish a baseline.
Green Screen
Isolates the green sub-pixel — the other half of the yellow combination.
Pink Screen
The other secondary color — tests the red+blue combination without green.
Color Accuracy Test
Measures ΔE deviation for yellow and other secondary colors against sRGB targets.
Continue your display inspection
The yellow screen tests red+green sub-pixel combinations and serves as a warm photography light. Open the full toolset to verify every channel combination and complete your pixel inspection.