What is a moire effect?

A moire effect overlays two regular patterns at a slight angle, producing a third much coarser pattern that exists in neither of them. It is interference rather than texture.

Why do printers rotate halftone screens?

To avoid moire. Four ink screens at the same angle interfere and produce a visible beat pattern, so they are offset to 15, 75, 0 and 45 degrees to keep their dots from nearly coinciding.

Why do striped shirts shimmer on camera?

The stripe frequency beats against the sensor's pixel grid, producing moire. It is why many cameras include an optical low-pass filter that deliberately softens fine detail.

moire effect

SourceEffect

01/ ORIGIN

who, when, what for

Moire is interference, not texture. Overlay two regular patterns at a small angle and a third, much coarser pattern appears that exists in neither of them, produced purely by where their elements nearly coincide. It is the reason printers rotate CMYK halftone screens to specific angles, the reason a striped shirt shimmers on television, and the reason camera sensors ship with optical low-pass filters. Almost every use of the word describes something an engineer was trying to eliminate.

02/ SWEEP

PITCH · min / mid / max

PITCH sweep

PITCH 1pxPITCH 1: very fine grids, the beat pattern coarse and dominant

PITCH 3pxPITCH 3: the default, interference clearly readable over the subject

PITCH 12pxPITCH 12: coarse grids, the beat widening toward plain stripes

03/ SPEC

the real controls

This effect generates two overlapping regular line patterns at an angular offset, so the visible beat pattern is genuine interference rather than a texture drawn on top. PITCH runs from 1 to 12 pixels with a default of 3 and sets the line spacing of the grids, which together with the offset determines how coarse the resulting beat is. SEPARATION and ANGLE control the offset between the two grids, WEIGHT sets line thickness, and SHIMMER is an advanced control. In kott it renders in natural colour so the beat reads against the source hue.

PITCH1 px to 12 px · default 3 px

SEPARATION0 to 1 · default 0.4

ANGLE0 rad to 3.1416 rad · default 0.4 rad

WEIGHT0 to 1 · default 0.5

04/ FAQ

questions people actually type

What is a moire effect?: A moire effect overlays two regular patterns at a slight angle, producing a third much coarser pattern that exists in neither of them. It is interference rather than texture.
Why do printers rotate halftone screens?: To avoid moire. Four ink screens at the same angle interfere and produce a visible beat pattern, so they are offset to 15, 75, 0 and 45 degrees to keep their dots from nearly coinciding.
Why do striped shirts shimmer on camera?: The stripe frequency beats against the sensor's pixel grid, producing moire. It is why many cameras include an optical low-pass filter that deliberately softens fine detail.

05/ OUT

open it, then browse

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