Spectral transition guide

Overview

Spectral transition turns one picture into another one layer of detail at a time: broad shapes in one turn, fine texture in another.

A pale, pearl-crowned face and far spires forming inside a blue filigree halo, with strings of beads and praying hands still sharp from the first picture
The Apparition preset partway through: the broad shapes of picture B have arrived, while fine detail of picture A still shows.

It is an image transition between two pictures, A and B. See picture A and picture B.

Each picture is split into layers, from broad shapes to fine texture. Broad shapes are low spatial frequency; fine detail is high. See image bands.

By default the tool makes those layers with a Laplacian pyramid: copies of the picture at halving sizes, each blurred, with each layer holding what one copy has and the next, smaller one lacks. Adding every layer back together gives the whole picture again. See image pyramid and reconstruction.

The Method choice has a second way: a Fourier transform splits the picture into waves, from slow to fast, and the Fourier method changes rings of those waves, each in its own turn.

Each layer changes from A to B in its own turn. See band stagger. With structure first, B's broad shapes arrive before its detail; with detail first, the other way.

One number, the transition progress, runs from 0 to 1 over the run, and an easing curve sets how it speeds up and slows down. The layers are built and added up on the GPU.

After each run the direction flips: the next run carries B back into A.

Five presets set every control at once: Apparition, Structure first, Texture swap, X-ray cross and Spectral dissolve. You can swap in your own two pictures, and keep a PNG or a video.

Open Spectral transition Start here

In this guide

  1. StartWhat you need and your first run in five steps.
  2. Every controlEvery control in the panel, one line each.
  3. Three looksThree presets caught mid-change, and how each was made.
  4. Keep your workThe PNG and the video.
  5. HelpWhat to do when something goes wrong.

It runs in your browser with WebGL 2. Your pictures stay on your device and nothing is uploaded. A mouse, a trackpad, a pen and a finger all work.