Fine Line & Spatial Frequency Test
Presents precision 1-pixel and 2-pixel line patterns in vertical, horizontal, diagonal, and crosshatch orientations. Critical for spotting uneven line thickness, phase jitter, and non-integer scaling artifacts.
Technical Scope & Limitations
Requires exact pixel rendering. On mobile devices with non-integer DPR, lines may exhibit unavoidable subpixel blending.
Browser rendering output can be influenced by OS display scaling, GPU driver color settings, and active HDR profiles.
- Enter fullscreen mode on a desktop or laptop.
- Cycle through vertical, horizontal, and diagonal 1px lines.
- Every line should maintain identical thickness and contrast across the entire width of the display.
- Any waviness or thickness variation indicates display scaling or interpolation.
What This Test Checks
- 1px vertical and horizontal line consistency.
- Line phase jitter and non-integer scaling distortion.
- Crosshatch and diagonal line rendering fidelity.
How to Perform the Test
- Enter fullscreen mode on a desktop or laptop.
- Switch between 1px vertical, horizontal, diagonal, and crosshatch patterns.
- Inspect the pattern across the full screen width and height.
What to Look For
- All lines should have identical width and contrast with zero thickness modulation.
- Uneven line widths or wavy banding indicate non-native scaling.
Common Display Problems & Diagnostic Guidance
Chroma Subsampling (4:2:0 vs 4:4:4)
Over HDMI or limited bandwidth connections, GPU output may compress color to YCbCr 4:2:0, blurring colored fine lines. Set GPU output format to RGB 4:4:4 Full Range.
Frequently Asked Questions
Why do diagonal lines look stepped?
Physical display panels are arranged in a rectilinear grid of square pixels. Without anti-aliasing, a 1px diagonal line naturally exhibits single-pixel steps (aliasing).