Mach Bands
Mach Bands — 2026, generated SVG, dimensions variable · Luminance · Still
After Ernst Mach, 1865
Do you see extra bands near the ramp?
Does a bright band appear at the boundary?
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Reveal the answer
The brightness runs flat, then linear, then flat again — no extra bands exist.
↑ The mechanism, made visible.
Notes — why it looks that way
What is happening
There are three sections: a flat dark area on the left, a smooth transition in the middle, and a flat light area on the right. Watch whether a bright line appears at the boundary between the middle and right sections, or a dark line appears at the boundary between the middle and left. The effect is fairly subtle — you don’t need to see several distinct stripes for it to count.
Why it looks that way
Your visual system is also sensitive to changes in brightness. Near where a flat region meets a sloped one, brightness can appear more exaggerated than the actual values. This is linked to how the retina works, but the fine details of the mechanism can’t be reduced to a single simple stage.
How to check
The line graph under the “answer” view schematically shows the gray values as drawn. Notice that there is no peak poking up in the bright region and no dip sinking down in the dark region. Display calibration and viewing environment also affect this, so don’t confuse the strength of what you perceive with an actual measurement.
For reference: Michael Bach’s explanation. The figure here is an original implementation for this site.
First described
After Ernst Mach, 1865
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 Mach bands principle is re-implemented here as SVG. No existing figure or code is reproduced.