RGB Channel Test
FreeTest your screen for dead, stuck, or hot pixels with pure red/green/blue channel isolation plus any custom color via hex or picker.
Runs entirely in your browser.
Keyboard: arrow keys to switch preset, F for fullscreen, Esc to exit.
What this tool does
This tool displays pure red, green, blue, white, or black fullscreen, right in your browser, plus any custom color you choose with a hex input or color picker, to help you isolate and spot dead, stuck, or hot pixels on your display.
How It Works
Every pixel on a typical display is made of three subpixels, one red, one green, and one blue, blended together to produce the color you actually see. When you fill the whole screen with pure red for example, only the red subpixels should be lit anywhere on the panel, so if a green or blue subpixel is stuck on, it stands out as an unexpected colored speck against the flat red field, something it could easily hide inside on a busy image or even on plain white. Custom colors entered as hex (like #ff8800) or picked visually are validated and normalized before being applied, accepting both 3-digit and 6-digit hex shorthand.
Problems it solves
- Finding dead, stuck, or hot pixels on a new or secondhand screen before a return window closes.
- Isolating which specific color channel a subpixel fault affects.
- Checking a custom color for uniformity, tinting, or banding issues.
- Getting a clean, distraction-free full-screen color reference for photography or documentation.
Frequently asked questions
›Why test pure red, green, and blue instead of just white?
A pixel is really three subpixels layered together, and white blends all three at once, so a single faulty subpixel can be masked by the other two. Viewing one channel at a time removes that camouflage and makes a subpixel fault far easier to spot.
›What is the difference between a dead, stuck, and hot pixel?
A dead pixel stays black no matter what color you display, since none of its subpixels are working. A stuck pixel shows one fixed color regardless of what should be there, because one or more subpixels are locked on. A hot or bright pixel is the opposite of dead, always fully lit and usually appearing white.
›Why does the tool include a custom hex color and color picker, not just R, G, and B?
Beyond the three primary channels, viewing specific in-between colors can help you spot subtler issues like color tinting, banding, or a stuck subpixel that only becomes obvious against a particular shade, the picker lets you test any color you want, not just the three primaries.
›Should I test in fullscreen?
Yes, browser chrome and other windows can hide pixels near the edges and corners, which is exactly where manufacturing defects are statistically more common, fullscreen mode makes sure every physical pixel is actually covered by the test color.
›Can this test fix a dead or stuck pixel?
No, this tool only helps you find and confirm pixel issues visually, it cannot repair hardware. Some stuck pixels (not dead ones) have occasionally been resolved by dedicated pixel-massaging or rapid color-cycling techniques found elsewhere, with mixed and unreliable results.
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