RGB Test

How this test works

Cycle through primary colors and channel ramps to spot clipping, tint, and subpixel problems.

1. Prepare the display using the checklist below.
2. Select Start test and allow fullscreen mode if your browser asks.
3. Use the arrow keys, on-screen controls, or click the pattern to move through the test.
4. Exit the runner and save a local observation if useful.

Before you begin

• Disable color filters and night light
• Use a neutral picture mode
• Set browser zoom to 100%

What to look for

• Missing or uneven color channels
• Abrupt changes between saturation steps
• Persistent pixels on solid RGB fields

Inspect the red, green, and blue paths separately

The RGB runner displays solid red, green, and blue, a combined color grid, and stepped ramps for each primary channel. Begin with a neutral picture mode and temporarily disable night light or other color filters. Inspect each solid field for a broad tint, a missing-looking channel, or an isolated point that behaves differently. Then compare the ramps: nearby steps should remain distinguishable enough to reveal abrupt clipping. This is a channel-oriented visual check, narrower than the general monitor color overview.

A solid color may reveal an isolated subpixel fault, but that observation belongs with the five-color dead pixel check for confirmation. A whole-screen change in one primary can instead involve a profile, graphics output, application rendering, or display setting. Note whether the anomaly appears in every field, in just one channel, or only within a particular saturation range. Those distinctions are useful for troubleshooting, but the web page cannot identify which cable, processor, or panel circuit is responsible.

Compare ramps without assuming calibrated output

The numerical CSS values define the browser’s requested colors, not the photons measured at the panel. Operating-system color management, the ICC profile, graphics pipeline, display mode, and panel gamut all affect what reaches your eyes. The page cannot calculate chromaticity, Delta E, or gamut coverage. A bright green may look different from another display simply because their brightness or color spaces differ. Equalize viewing conditions before using a side-by-side comparison as a clue.

Use browser zoom at 100% and keep the window on the target monitor. If the ramps change after switching to an sRGB preset or correcting a display profile, record that setting. Do not change several controls at once or conclude that the preset with the most saturated primaries is the most accurate. Stronger color is not automatically more faithful. A colorimeter or spectrophotometer with controlled software is needed for objective output measurements.

Follow the shape of the problem

If one tiny point remains the wrong color, move to the dead pixel test and compare black and white as well as the primary colors. If a large area is tinted, use neutral-gray uniformity fields. If the concern is whether web content is managed in sRGB or Display P3, the focused gamut pages answer a different question. The RGB test is most useful when you need to isolate a primary channel or inspect obvious clipping in its stepped values.

Document the affected color, step range, position on the panel, picture mode, browser, and input. Repeat the observation in a second piece of content before declaring a hardware fault. A screenshot may reveal a software-generated anomaly, while a physical point will not be captured as emitted light in the screenshot; neither check by itself is a diagnosis. Use the result as a concise description of visible behavior, and seek instrument-based testing if exact color reproduction is important for your work.

Frequently asked questions