NEW TO THIS? HERE’S THE PLAIN-ENGLISH VERSION.
What this test is
Fine white lines on black that reveal whether each pixel’s red, green, and blue elements line up — or leave a coloured fringe.
How it helps you
It explains fuzzy, coloured edges on text and confirms whether it’s a fixable rendering setting or a real panel defect.
What we’re checking
Whether fine white lines look pure white, or carry a red/green/blue fringe that signals a convergence problem.
Look closely at the white lines. They should be perfectly white. Any color fringing (e.g., red, green, or blue edges) indicates a convergence problem. Check the center and the corners of the screen.
F11 or Full Screen · ← → patterns · Esc exit
What Convergence Is
Convergence is the alignment of the three sub-pixel elements — red, green, and blue — that form each pixel. When they align precisely, fine white detail looks pure white. When they don’t, you get coloured fringing around high-contrast detail, most visible on white text against black. True convergence errors are manufacturing defects — they can’t be adjusted by the user, so the only question is whether yours is within tolerance or bad enough to return.
How to Use the Test
- 1Go fullscreen. Press Full Screen and bring up the fine line or cross-hatch pattern.
- 2Check white lines on black. On 1-pixel white lines against black, each line should be pure white with no coloured fringe.
- 3Scan centre to edges. Convergence errors are worst at the corners and edges — work outward from the middle.
- 4Verify it’s not angle-related. View straight-on and at slight angles. Convergence fringing stays constant; IPS glow shifts with angle.
Convergence Severity
| What you see | Assessment |
|---|---|
| White lines pure white, no colour | Convergence excellent |
| Very faint fringe, only visible inches away | Within tolerance — normal |
| Fringe visible at normal distance | Mild convergence issue |
| Distinct red/green/blue shadow on text | Significant convergence failure |
| Double image on fine lines | Severe manufacturing defect |
Not All Fringing Is a Convergence Error
ClearType / font smoothing deliberately uses coloured sub-pixels to smooth diagonals — that fringing is by design and disappears when you turn the feature off.
IPS glow can wash colours into bright elements at wide angles — but it shifts as you move your head. True convergence failure appears on fine detail at a normal distance and straight-on, and stays put.
If the fringing is really softness rather than colour offset, check native-resolution rendering with the pixel grid test, and confirm any isolated coloured dot with the dead pixel test.
Convergence FAQ
Can convergence errors be fixed?+–
No. LCD convergence errors come from the physical panel manufacturing and cannot be corrected in software or the OSD. Mild errors are within normal tolerance; severe fringing that affects text readability warrants a return or warranty claim.
Is convergence the same as chromatic aberration?+–
In monitors they describe the same visible effect. Chromatic aberration is the optical term for wavelength-dependent separation; convergence error is the display-industry term. Both refer to colour fringing around high-contrast detail.
Does convergence only affect LCDs?+–
LCD panels with separate red/green/blue sub-pixel elements can show convergence issues. OLED uses a similar sub-pixel structure but is manufactured differently, so convergence errors are extremely rare. The term originates with CRT monitors, which needed manual convergence adjustment.
How do I know if it’s ClearType fringing or a real convergence error?+–
Temporarily disable ClearType (Windows) or LCD font smoothing (macOS). If the coloured fringing disappears, it was font rendering. If it persists on test patterns and images regardless of font settings, it is a panel convergence issue.
How much fringing is normal?+–
A very faint fringe visible only inches from the screen is within tolerance on most consumer panels. Fringing visible at a normal viewing distance is a mild issue; a distinct red, green, or blue shadow on text, or a double image on fine lines, is a significant defect.
Where on the screen is convergence usually worst?+–
Convergence errors are typically most visible at the corners and edges, where panel tolerances stack up, and least visible at the centre. Scan systematically from the middle outward, and check that the fringing stays consistent as you shift your head — if it changes with angle, it’s more likely IPS glow than convergence.
Does convergence affect image quality or just text?+–
It is most obvious on high-contrast fine detail — white text on black, thin lines, small icons — because that is where a slight sub-pixel offset shows as colour. On photos and video it is usually imperceptible. If your work is text- or line-heavy (coding, CAD, design), it matters more.
Related Monitor Tests
Checking a whole new panel?
Run the dead pixel test and browse the full monitor test suite.