Description

A Pebble can show 64 colours. A rainbow needs a few more than that. Prism gets them by dithering: every pixel picks one of the two nearest colours the screen really has, in a fine ordered pattern, so that from arm's length red melts into orange, yellow into green, blue into violet - without the hard stripes a 64-colour gradient would otherwise break into.

The rainbow can live in the numerals - large LECO 1976 digits, hours above minutes, filling the display - or behind them, with the digits cut out in a single plain colour. Either way the spectrum is stretched over exactly the part that shows it, so the round face of the Pebble Round 2 gets the whole rainbow too, not just the middle of it.

Give it an outline, thin or bold, in any colour - a white edge makes black numerals on a rainbow stand out, and rainbow numerals glow on black.

Let the colours run diagonally, top to bottom, left to right, or in an arc like the real thing. Or let them turn: in Turning mode the rainbow makes one full revolution every hour, and its red end points at the current minute like a hand.

Drift with the day shifts the whole spectrum once around the colour wheel in 24 hours, so the face looks a little different every time you raise your wrist. And if you like to see the trick, switch the dither to Retro: chunky 2 x 2 pixels, straight out of an 8-bit game.

The face is drawn once a minute and then left alone. No Bluetooth traffic, no sensors, no animation in between.

Made for Pebble Time 2 and Pebble Round 2.