Text Clarity & Subpixel Antialiasing
Displays text samples from 10pt to 24pt in light-on-dark, dark-on-light, and medium contrast modes to evaluate OS font rasterization, subpixel antialiasing fringing, and high-DPI scaling.
Technical Scope & Limitations
Browser font rasterization is determined by OS font smoothing (ClearType / macOS Quartz). The web page cannot override OS-level font smoothing.
Browser rendering output can be influenced by OS display scaling, GPU driver color settings, and active HDR profiles.
- Observe text samples across different sizes and weights.
- Check whether small text (10pt–12pt) remains legible and sharp.
- Look for colored color-fringing (red or cyan halos) around letter edges, which may indicate subpixel antialiasing mismatch.
What This Test Checks
- Typography legibility across sizes from 10pt to 22pt.
- Subpixel antialiasing fringing on light and dark themes.
- Operating system font rasterizer rendering behavior.
How to Perform the Test
- Inspect the typography lines from 10pt up to 22pt.
- Toggle between Black on White, White on Dark, and Gray on Dark modes.
- Check whether thin font stems appear solid black or show colored fringes.
What to Look For
- Clean, solid letterforms with sharp outlines.
- Noticeable colored halos (pink or blue fringes) indicate subpixel orientation mismatch.
Common Display Problems & Diagnostic Guidance
ClearType Optimization in Windows
Open Windows Start and search for "Adjust ClearType text". Step through the calibration samples to select the crispest rendering for your monitor subpixel geometry.
Frequently Asked Questions
Does macOS use subpixel antialiasing?
Modern versions of macOS (since Mojave) disabled subpixel antialiasing by default in favor of grayscale antialiasing, optimized for high-DPI Retina screens.