Red + green = yellow
The canvas requests full red and green with blue at zero. The visible yellow depends on the display primaries and color pipeline; it is not a measured spectral mixture.
Inspect additive channels independently
RGB Screen Test
The screen RGB test provides full red, green, and blue fields, smooth 0–255 channel gradients, deliberate 16-step ramps, and additive yellow, magenta, cyan, and white mixes. It can help you observe channel-specific pixels, obvious transition artifacts, and broad field changes without pretending to calibrate RGB balance by eye.
One coordinate, three primary fields
Use the RGB test for a fixed pixel symptom
- Inspect the surface first. A speck or reflection can imitate a dark or bright pixel. Follow only coating-safe manufacturer cleaning guidance and never press, rub, tap, or heat the panel.
- Open the red field. Enter fullscreen, hide the controls, and scan in a consistent path. Note a suspect point’s coordinate rather than chasing its apparent color.
- Switch to green and blue. Keep looking at the same coordinate. A point that changes relative to individual RGB fields may indicate channel-specific behavior, but the visual RGB test does not inspect subpixel electronics directly.
- Compare additive mixes. Yellow requests red plus green, magenta red plus blue, cyan green plus blue, and white all three channels. These combinations help cross-check an obvious channel response.
- Return to ordinary content. Record whether the mark is visible at a normal distance. Retailer or manufacturer policy—not this page—determines whether an observation qualifies for service or return.
Additive mixing in four requested outputs
How RGB channels combine
Red + blue = magenta
Magenta places red and blue at full code value. Compare a fixed point with the separate red and blue fields if one part of the mix looks inactive or unusually bright.
Green + blue = cyan
Cyan combines green and blue. The RGB test uses this secondary field as a functional cross-check, not evidence of correct chromaticity.
RGB = white
Equal full requested channels create the canvas white field. Unaided viewing cannot tell whether that white meets D65 or any other calibrated white point.
Fields, gradients, and steps
Choose the RGB test pattern for the symptom
Full fields for uniformity and pixel response
One primary channel fills the entire RGB test canvas. This makes fixed dark points and broad channel-specific shading easier to compare. During the RGB test, inspect from the center first, since viewing angle can change apparent color and uniformity.
0–255 gradients for visual continuity
Each smooth ramp changes one requested channel from zero to 255 while the other two remain zero. Visible contours in the RGB test can come from the source-to-panel pipeline and do not prove native bit depth. The dedicated banding tooladds secondary ramps and smooth-versus-stepped controls.
Sixteen steps for a known reference
The stepped RGB test patterns intentionally divide a channel into sixteen integer code values. Use them to recognize a deliberate boundary and to check that neighboring patches progress visually. Do not count those patches as the number of colors the panel can display.
Describe the pattern you see
Useful RGB test observations
One fixed point changes by channel
A pixel-sized point that remains at the same coordinate but responds differently on red, green, and blue may indicate stuck or non-responsive subpixel behavior. Dust and scaling still need to be excluded.
A broad area shifts or darkens
An area larger than one pixel belongs to a uniformity observation. Compare full RGB fields with neutral grey and vary viewing position separately before assigning a cause.
A ramp has abrupt transitions
Record the channel, direction, picture mode, and whether the edge also appears in the stepped reference. Browser rendering, output settings, and panel processing all remain possible contributors.
Rendering method
What this RGB test sends to the canvas
Full fields in the RGB test use one CSS-compatible RGB triplet. Smooth ramps use a linear canvas gradient, while stepped ramps calculate sixteen evenly spaced integer values. The mix pattern divides the field into four labeled channel combinations. Fullscreen changes the canvas size, not the requested color definitions. No camera, upload, sensor, or automatic pixel counter is used.