> The Short Answer
Luma Stretch reads each pixel's brightness, turns the pixels past a threshold into anchor points, and stretches the rest toward them — brightness becomes velocity. Direction sets the metaphor: horizontal reads as speed, vertical as rain or falling, radial as an explosion or zoom. Intensity 1-30% is a subtle hint of motion, 30-60% is clear action, and 60-100% turns pixels into full streaks. Stretching highlights only makes the subject look like it is emitting light.
What is Luma Stretch?
Luma Stretch analyzes brightness values and stretches pixels directionally. Bright areas pull, dark areas anchor (or vice versa). The effect looks like speed lines or motion trails.
How It Works
- Scan each pixel's brightness (0-255)
- Pixels above/below threshold become anchor points
- Other pixels stretch toward those anchors
Parameters
Direction
- Horizontal: speed lines, car zooming past
- Vertical: rain, falling sensation
- Radial: explosion or zoom blur
Intensity
- 1-30%: subtle motion hint
- 30-60%: clear action feel
- 60-100%: full warp, pixels become streaks
Threshold
- Bright only: highlights stretch, ethereal glow
- Dark only: shadows stretch, noir drama
- Both: maximum distortion
Good Subjects
- Portraits: hair flows like energy
- City lights at night: neon streaks
- Sports photos: frozen motion with implied speed
Techniques
Double Pass: Horizontal first, then vertical at lower intensity. Creates a cross-hatch pattern.
Selective Stretch: Only stretch highlights. Subject looks like it's emitting light.
With RGB Shift: Add chromatic trails. Looks like faster-than-light travel.
The Point
Photos freeze time. Luma Stretch lets it leak out.
> Frequently Asked
- What does Luma Stretch do?
- It scans the brightness of every pixel, treats pixels past the threshold as anchors, and stretches the surrounding pixels directionally toward them. The output looks like speed lines or motion trails drawn out of the light in the photo.
- Which direction should I use?
- Horizontal for speed, like a car passing the frame. Vertical for rain or a falling sensation. Radial for an explosion or zoom-blur effect that pushes outward from the centre.
- How do I add motion trails without destroying the subject?
- Use selective stretch on highlights only and keep intensity under 60%. The bright areas streak while the subject keeps its edges, which reads as the subject emitting light rather than the whole frame smearing.