Hermann Grid
Hermann Grid — 2026, generated SVG, dimensions variable · Luminance · Still
After Ludimar Hermann, 1870
Are there gray spots at the crossings?
Are there gray dots at the intersections?
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Reveal the answer
Both the intersections and the paths are white. No gray dots are drawn.
↑ The mechanism, made visible.
Notes — why it looks that way
What is happening
Fix your gaze on one intersection while keeping the neighbouring ones in view. Gray smudges may appear at the intersections around the edge of your vision, and they fade or vanish when you move your eyes directly onto them. No animation is used — the intersections are painted in exactly the same white as the paths between them.
Why it looks that way
Brightness estimation is affected not just by a single pixel, but by the surrounding layout and line direction. The context at an intersection differs from the context along a path. This has long been explained by lateral inhibition in the retina, but some properties of the effect are known not to be fully explained by that alone.
How to check
Revealing the answer outlines two small squares: one at an intersection, one partway along a path. Both are confirmed to be flat white areas. The strength of the smudges changes with screen size and viewing distance, so rather than staring hard at one spot, try scanning the whole figure comfortably.
For reference: Michael Bach’s explanation. The figure here is an original implementation for this site.
First described
After Ludimar Hermann, 1870
Media — images and data
- OG / X (1200×630)
- Instagram square (1080×1080)
- Shorts / Reels vertical (1080×1920)
- Answer image — landscape (X)
- Answer image — square (Instagram)
- Answer image — vertical (Shorts)
- Post drafts (JSON)
Free to use for non-commercial purposes such as classes, school projects and blogs, with a link back to this page as the credit. Commercial use is not covered
Every figure is generated here from the phenomenon itself (re-implemented). The general Hermann grid principle is re-implemented here as SVG. No existing figure or code is reproduced.