Pixel Rain Lab

What is pixel sorting

Pixel sorting is a glitch art technique that reorders the pixels of an image by a value such as brightness, hue or saturation. The sort runs along rows or columns, and usually only inside spans picked by a threshold, so some parts of the picture stay intact while others turn into hard streaks of graded color. The German artist Kim Asendorf published one of the first open-source pixel sorting tools, a Processing script called ASDFPixelSort.

A sorted image is a still. Pixel Rain Lab animates the sort instead: the clip opens on your untouched photo, the sort spreads across it, and the sorted streaks keep falling until the end. That falling phase is where the name comes from.

How Pixel Rain Lab sorts a photo

The tool works on vertical columns one pixel wide. In each column it cuts the pixels into runs and sorts every run by brightness, darkest at the top and brightest at the bottom, so each run becomes a short gradient. Streak length sets the average length of those runs, from 2% to 45% of the frame height.

A mask decides when each pixel melts, meaning when it joins a sorted run. The mask grows over the first seconds of the clip, starting from the area picked under Melt starts from: the top, the bottom, the center, or the brightest parts of the photo. Coverage limits how much of the photo can melt. At 100% every pixel ends up sorted; lower values leave the darker areas as they were.

Once the melt is complete, the cuts between runs scroll down each column. Every column moves at its own speed, between 0.55 and 1.45 times the rate set by Rain speed, and that difference between neighboring columns is what reads as rain. Rises reverses the direction. Shuffle the rain draws new cut points and column speeds and keeps every other setting.

Which photos work best

Sorting can only move pixels that differ from their neighbors. A clear sky or a flat wall is already close to sorted, so it barely changes when it melts. Point lights, neon signs, bokeh and reflections on water give the sort bright pixels to pull into long streaks, and a dark background keeps those streaks readable. Night photos work well for that reason. The three clips above start from two multiple exposures and a double exposure.

Export and privacy

Everything runs in your browser. The photo is decoded, sorted and encoded on your device and is never uploaded. The video is encoded as H.264 at 30 frames per second, 1080 or 720 pixels wide, with the WebCodecs API, then packaged as an MP4 file by the open-source mp4-muxer library (MIT license). You can pick a 3:4, 4:5 or 9:16 frame and a length of 10, 20 or 30 seconds; 9:16 fits Reels, Stories and TikTok.

Export works in recent versions of Chrome, Edge and Safari on a computer, and a 30-second clip takes about a minute. The tool is free, needs no account and adds no watermark.