The pixel stretch effect, and how to make one on a phone

You have seen this on album covers and posters: a photograph where part of the image dissolves into bands of colour running off the edge of the frame, as though the picture were melting sideways.

The mechanic behind it is simpler than it looks.

What the effect actually is

Take a photo. Pick one row of pixels — a single horizontal line, one pixel tall. Now repeat that exact row downward, hundreds of times, until it fills the bottom half of the image.

Every colour that happened to fall on that line becomes a vertical stripe. A bright window becomes a bar of yellow. A dark gap between buildings becomes a black band. The result reads as motion or as light bleeding, even though nothing has moved and nothing has been painted in.

That is the whole idea. Everything else — curves, tapering, protecting a subject from the smear — is refinement on top of it.

Why the placement of the line decides everything

Because the stretch is a copy of one line, the entire result is determined by which line you choose. Move it up by twenty pixels and you get a completely different image.

• Pick a line with contrast. A row that crosses lights, edges or strong colour gives you ribbons. A row through a flat grey sky gives you a flat grey rectangle.
• Stretch away from the subject, not through it. If the line sits across a face, the face smears. Usually you want the line just below or beside the thing you are keeping.
• Long stretches read as motion; short ones read as texture. Both are useful, and they are different pictures.
• Night shots are the easy win. Point lights against dark backgrounds produce the cleanest ribbons, which is why so many examples of this effect are cities at night.

How it is normally done, and why that is annoying

In Photoshop the recipe is: rectangular marquee, drag a selection one pixel tall, copy to a new layer, free transform, then drag the handle to the edge of the canvas. It works, it has worked for twenty years, and it needs a desktop and a licence for what is fundamentally one operation.

The phone versions of this mostly do not exist. Filter apps offer a fixed "stretch" preset with no control over where the line goes, which — given the previous section — means no control over the result.

Doing it on the phone

Slean includes a pixel stretch editor on both iPhone and Android. You draw the stretch path directly on the photo, and the ribbons follow it.

1. 1Open a photo in Slean and choose Pixel Stretch.
2. 2Move the sampling bar over the exact strip of colour you want to pull. This is the decision that makes or breaks the image — everything downstream is a copy of what sits under that bar.
3. 3Tap the arrow for a straight pull, or drag it to draw a curve through the composition. Curved paths get draggable control points, so a rough route can be nudged into the shape you meant.
4. 4Shape bends the centreline; Warp changes the ribbon's width along its length. There are presets for the two shapes people reach for most — a rounded arc and an S curve — which beat drawing a smooth curve by hand on a phone screen.
5. 5Tune the taper, twist, opacity and coloured edges, comparing against the original as you go.
6. 6Turn on subject protection if the ribbon is eating into something you wanted to keep sharp.
7. 7Save. The export is full resolution, not a downscaled preview.

Two controls do most of the work and they are worth separating in your head. Shape decides where the ribbon goes. Warp decides how thick it is along the way. A ribbon that reads as motion is usually a simple path with a strong taper; one that reads as texture is a busier path held at an even width.

All of this happens on the device. The image is not uploaded anywhere to be processed, and the export is fast enough that you are not left watching a spinner.

Things worth knowing before you try it

• The effect is destructive to whatever it crosses. Work on a copy if the original matters, or use subject protection.
• It rewards flat, graphic compositions. A busy scene with detail everywhere turns into noise when smeared.
• It is one of the few effects that still looks deliberate at high strength. Half-hearted stretches usually look like a rendering error rather than a choice.
• On iPhone, Pixel Stretch needs iOS 17 or later, even though Slean itself runs on iOS 15.