Kaleidoscope

2–32 segments · rotation · zoom · square output

A kaleidoscope takes one wedge of the image and mirrors it around the centre. The mirroring is the important part: reflecting alternate wedges rather than merely rotating them means adjacent copies meet along a matching edge, so the seams disappear and the result looks like a single continuous pattern.

Segments, rotation and where the pattern comes from

Only one narrow wedge of the source ever appears — everything else in the picture is ignored. With six segments that wedge is 30° wide, taken clockwise from the three-o'clock direction. Which part of the image lands in it is what the rotation control decides, and rotation is by far the most useful dial here: leaving the segments alone and sweeping the rotation through 60° gives completely different patterns from the same photo.

Fewer segments keep more of the original recognisable — four or six still reads as "a mirrored photograph". Twelve and above stops looking like a photograph at all and becomes ornament, which is usually the point. Odd numbers work but are less symmetric, because a mirrored pair takes two wedges; the effect is a pattern with a visible spiral bias, which is sometimes exactly what you want.

Zoom scales the sampling radius. Below 100% the wedge is sampled from further out in the source, pulling in the outer detail; above 100% it magnifies the area near the centre, which produces broader, softer shapes. If the corners of the output come out transparent, the sampled radius has run past the edge of the source — raise the zoom or use a larger image.

Choosing a source image

Busy, colourful, high-contrast images work best: flowers, foliage, fabric, rust, graffiti, abstract paint. What you want is texture with strong local variation, because the pattern is built from a thin slice and a flat slice produces a flat result. A portrait or a photo with a large area of plain sky will give you a mostly empty kaleidoscope — the interesting parts are unlikely to fall inside the wedge.

FAQ