llinescan/readme.md

Strip Photography / Slit Photography

A digital implementation of strip photography (also called slit photography) that captures a two-dimensional image as a sequence of one-dimensional images over time.

Strip photography records a moving scene over time by extracting the same line position from each video frame and assembling them into a composite image where:

• One axis represents space (the slit/line being observed)
• The other axis represents time (progression through video frames)
• Moving objects appear as visible shapes, stationary objects as stripes
• Object width is inversely proportional to speed (faster = narrower, slower = wider)

Usage

Row Mode - Extract horizontal lines with threshold filtering:

uv run main.py .\line500fps32pix.mp4 --yrow 16 --output demo.jpg --threshold 0.005

Debug Mode - Analyze changes and generate threshold recommendations:

uv run main.py .\line500fps32pix.mp4 --yrow 16 --output demo.jpg --debug

Setup

Install dependencies with uv:

uv sync

Output Modes

• Column mode: Extracts vertical line (--xcolumn) → Width = frames, Height = video height
• Row mode: Extracts horizontal line (--yrow) → Width = video width, Height = frames

Features

Change Detection: Automatically filters frames with minimal changes using configurable thresholds

• Use --threshold (0-1) to control sensitivity
• --debug mode provides threshold recommendations and change analysis
• Higher thresholds = more compression, fewer frames

Threshold Guide:

• 0.001-0.005: High sensitivity (10-30% compression)
• 0.005-0.02: Medium sensitivity (30-70% compression)
• 0.02+: Low sensitivity (70%+ compression)