What a screen color test actually shows you
A screen color test is one of the fastest ways to judge how good your display really is. Instead of staring at a desktop full of icons and windows, you fill the whole screen with a single solid color, then with smooth gradients, and watch how the panel behaves. Flaws that hide behind normal content suddenly become obvious: a single dot that refuses to change color, a glowing patch in one corner, a faint stripe across a sky-blue gradient, or a white screen that leans slightly pink. The tool at Screen Color Test runs entirely in your browser, so there is nothing to install and it works the same on a laptop, a desktop monitor, a tablet or a phone.
What the solid-color screens reveal
Each pure color stresses the panel in a different way, which is why cycling through them matters.
Black is the backlight bleed and contrast screen. In a dark room, a good display shows an even, deep black. If you see bright clouds or glowing strips creeping in from the edges and corners, that is backlight bleed or IPS glow, where light leaks unevenly around the panel. A little glow at sharp angles is normal on IPS screens; large bright blooms that you see even looking straight on are a defect.
White exposes color cast and uniformity. A neutral white should look the same brightness from edge to edge. A yellow, pink or blue tint usually points to the factory color-temperature setting rather than broken hardware. Patches that are noticeably dimmer or warmer than the center are a uniformity problem.
Red, green and blue are the subpixel screens. Every pixel is made of red, green and blue subpixels, and a single one failing only shows up on its own color. A dot that is dark on the red screen but fine on green and blue is a dead red subpixel. Running all three is how you separate a truly dead pixel (always black) from a stuck pixel (always lit in one color).
What the gradient screens reveal
A smooth gradient sweeping from dark to light is the toughest test of color depth. On a healthy 10-bit or well-dithered 8-bit panel the transition looks continuous. If you see distinct steps or stripes instead of a smooth ramp, that is banding. Banding most often comes from settings rather than the glass itself: an 8-bit panel with no dithering, a GPU driver set to limited color range or low bit depth, an HDMI cable or port that cannot carry the bandwidth, or aggressive compression. Grayscale gradients are especially good for spotting subtle banding and uneven brightness, because your eye is most sensitive to tone changes in neutral gray.
How to run it properly
The conditions matter as much as the test itself. Put the browser into full screen so no toolbars or borders distract you. Dim the room, especially for the black and backlight-bleed checks, because ambient light hides glow and exaggerates reflections. Clean the screen first, since dust and fingerprints look exactly like stuck pixels until you wipe them. Sit at your normal viewing distance and look straight on, then step back: many "dead" pixels turn out to be specks, and many uniformity worries vanish at arm's length. Cycle slowly through each solid color, give your eyes a second to adjust, and scan corner to corner.
Good versus bad: reading the results
A good display gives you deep even black, neutral white with no obvious tint, fully saturated red, green and blue with no dark dots, and gradients that flow without visible steps. A bad result is a black dot that survives every color (dead pixel), a colored dot that survives every color (stuck pixel), bright leaks at the edges that you see head-on (backlight bleed), large warm or dim regions (poor uniformity), or hard stripes in a gradient (banding).
Hardware fault or just a setting?
This is the question the test is really there to answer. Dead pixels, stuck pixels and pronounced backlight bleed are physical defects in the panel and cannot be fixed by tweaking software; if a new monitor shows several of them, that is a warranty matter. By contrast, a color tint, mild banding or a "too cool" white is usually a setting. Try switching the GPU output to full RGB range and the highest bit depth, set the monitor color temperature near 6500K, swap to a known-good cable, and re-run the gradient screen. If banding disappears, it was bandwidth or color depth, not the glass. For a focused dead-pixel hunt see the dead pixel test, and browse all device tests for refresh-rate, touch and ghosting checks. Remember the limit: this tool spots problems, but real calibration still needs a hardware colorimeter.
Frequently asked questions
What is the difference between a dead pixel and a stuck pixel?
A dead pixel stays black on every color because it gets no power, while a stuck pixel stays lit in one color such as red, green or blue. Cycling through solid colors tells them apart: a dead pixel is dark on every screen, a stuck pixel is dark on every screen except its own color.
Why does my white screen look slightly yellow or blue?
That is a color cast from the monitor color-temperature setting, not usually a hardware fault. Set the temperature near 6500K for neutral white. If only part of the screen is tinted while the rest is fine, that points to a uniformity issue instead.
Is some backlight bleed normal?
A little glow at the corners on IPS panels, visible mainly at sharp angles, is normal and is called IPS glow. Bright leaks you can see looking straight on in a dark room are true backlight bleed and count as a defect, especially on a brand-new display.
Why do I see stripes in the gradient screen?
Those steps are color banding. They usually come from settings rather than the panel: an 8-bit display without dithering, a GPU set to limited range or low bit depth, or a cable that cannot carry enough bandwidth. Switch to full RGB range and the highest bit depth, then test again.
Can this test calibrate my monitor?
No. It reveals problems such as dead pixels, tints and banding, but it cannot measure or correct colors. Accurate calibration needs a hardware colorimeter and calibration software. The browser test is for spotting faults and checking settings.
Does the test work on phones and tablets?
Yes. It runs in any modern browser, so the same solid-color and gradient screens work on phones, tablets, laptops and desktop monitors. Use full screen and a dim room for the most reliable read on any device.