pixelmatch

Diff images on CPU. Small, fast pixel-level image comparison library for e2e testing.

Features

• Pixel-by-pixel image comparison
• Customizable threshold and colors for diff output
• Anti-aliasing detection
• Fast and memory efficient

expected	actual	diff

Getting started

Add library to your package and give Uint8List with RGBA canvas to it somehow.

Usage

import 'package:pixelmatch/pixelmatch.dart';
import 'dart:typed_data';

void main() {
  // Prepare your image data as RGBA Uint8Lists
  final img1 = Uint8List(width * height * 4); // First image
  final img2 = Uint8List(width * height * 4); // Second image
  final diff = Uint8List(width * height * 4); // Output diff (or null)

  // Compare images
  final numDiffPixels = pixelmatch(img1, img2, diff, width, height, { 'threshold': 0.1 });

  print('Found $numDiffPixels different pixels');
}

Options

• threshold (default: 0.1): Matching threshold (0 to 1); smaller is more sensitive
• includeAA (default: false): Whether to skip anti-aliasing detection
• alpha (default: 0.1): Opacity of original image in diff output
• aaColor (default: 255, 255, 0): Color of anti-aliased pixels in diff output
• diffColor (default: 255, 0, 0): Color of different pixels in diff output
• diffColorAlt (default: null): Alternative color for dark on light differences
• diffMask (default: false): Draw the diff over a transparent background

Additional information

This is a Dart port of mapbox/pixelmatch.