Shot Diff - Smart Screenshot Comparison Utility

A server-side utility that compares two same-width images, generates pixel-difference maps, clusters differences into bounding rectangles, and outputs transparent overlays.

Features

• Pixel-level comparison with configurable threshold
• Difference clustering using contour detection
• Noise filtering by minimum area
• Visual output with transparent overlay rectangles
• CLI interface with customizable parameters

Installation

pip install -r requirements.txt

Usage

Basic Usage

python shot_diff.py image1.png image2.png

Advanced Usage

python shot_diff.py image1.png image2.png \
  --threshold 50 \
  --min-area 200 \
  --padding 10 \
  --output results \
  --verbose

Parameters

• --threshold, -t: Pixel difference threshold (0-255), default: 30
• --min-area, -m: Minimum rectangle area to keep, default: 100
• --padding, -p: Rectangle padding in pixels, default: 5
• --output, -o: Output directory, default: output
• --verbose, -v: Show detailed rectangle information

Output Files

• diff_map.png: Grayscale difference map (debugging)
• rectangles.png: Transparent overlay with bounding rectangles

Example

python shot_diff.py screenshot1.png screenshot2.png --verbose

Output:

Comparison complete!
Difference map saved to: output/diff_map.png
Rectangle overlay saved to: output/rectangles.png  
Found 3 difference regions

Rectangle details:
  1: x=150, y=200, width=120, height=80, area=9600
  2: x=400, y=100, width=200, height=50, area=10000
  3: x=50, y=500, width=300, height=150, area=45000