Kaleidoscope

The frame mirrors itself around a centre and the picture becomes a pattern. A face, a dancer or a street turns into geometry that still carries traces of what it was made from.

Recognition is the pleasure. The audience reads the pattern first and the source second, and the moment of working out what the segments are made of is the point.

A wedge of the image is copied around a centre point and flipped on alternate copies, so adjacent segments meet as mirror images. The seams land on lines of symmetry and disappear.

The segment count changes everything. Six segments read as a snowflake and stay close to the source. Sixteen read as lace and abandon it. Say the number.

What you feed it matters more than the mirroring. Strong diagonals and high contrast survive the fold. A soft, even image turns into a smear with a bright dot in the middle.

Use it for musical numbers, for title sequences, and for any passage where the subject should stop being a subject for a moment.

Skip it when a face has to be read. The fold cuts the face into wedges and the expression goes with it.

Slit-scan stretches one narrow strip of the image across time, so the result is a smear with direction. A kaleidoscope repeats a whole wedge around a point, so the result is a pattern with symmetry.

The test is whether the frame has a centre. Radial symmetry around a middle point is a kaleidoscope. A streaked corridor with no centre is slit-scan.

Busby Berkeley shot his dance numbers from directly overhead in the 1930s so that the dancers formed opening and closing symmetrical figures, and the By a Waterfall number in Footlight Parade (1933) is the best known of them.

The model returns a plain symmetrical portrait, mirrored once down the middle. Say radial symmetry and give the segment count, as the note asks.

The other failure is a pattern with nothing of the source left in it. Name what the segments are made of, so the shot keeps the thing it came from.