argos-ci / image-difference

Create image differential between two images

image-difference

⚠️ This project is deprecated and no longer maintained.

Create image differential between two images

The problem solved

This is a fork of image-diff that is no longer maintained. This was created as part of a visual regression project and now supported as part of Argos-CI.

Installation

image-difference depends on ImageMagick Please install this before continuing.

npm install --save image-difference

API

imageDifference(options) => Promise

Create image differential between two images

Arguments

1. options (Object)
   • options.metric (String, default to AE): Optional metric used for the computation of the output.
     • documentation
     • guide
     • implementation
   • options.actualFilename (String): Path to actual image file. must exist.
   • options.expectedFilename (String): Path to expected image file. must exist.
   • options.diffFilename (String): Optional path to output differential image.

Returns

Promise: Return the output of the process. It's an object that contains the width, height properties.

Also, depending on the metric used, we either returns value or value 1, value2, valueX. Those values are in the order of the ImageMagick output. For instance, with the default AE metric, value is the number of different pixels after the fuzz being applied.

Example

import imageDifference from '../src/imageDifference'

imageDifference(
  {
    actualFilename: `${__dirname}/images/hello-world.png`,
    expectedFilename: `${__dirname}/images/hello.png`,
    diffFilename: `${__dirname}/images/hello-diff.png`,
  },
  console.log
)

CLI Usage

Usage:  [options] <actual-filename> <expected-filename> [diff-filename]

Create image differential between two images

Options:

  -h, --help     output usage information
  -V, --version  output the version number

Benchmark

We use imagemagick1 as the default implmentation

image-diff diff x 1.11 ops/sec ±1.21% (25 runs sampled)
image-diff same x 1.07 ops/sec ±0.80% (25 runs sampled)

image-difference imagemagick1 diff x 4.43 ops/sec ±0.40% (41 runs sampled)
image-difference imagemagick1 same x 4.45 ops/sec ±0.49% (41 runs sampled)

image-difference imagemagick2 diff x 2.96 ops/sec ±0.49% (34 runs sampled)
image-difference imagemagick2 same x 2.94 ops/sec ±0.87% (34 runs sampled)

image-difference graphicsmagick diff x 2.32 ops/sec ±0.60% (31 runs sampled)
image-difference graphicsmagick same x 2.30 ops/sec ±0.72% (31 runs sampled)

pixelmatch diff x 0.79 ops/sec ±0.94% (23 runs sampled)
pixelmatch same x 3.58 ops/sec ±2.07% (37 runs sampled)

resemble diff x 0.59 ops/sec ±4.76% (22 runs sampled)
resemble same x 0.94 ops/sec ±0.85% (24 runs sampled)

looksSame diff x 2.09 ops/sec ±3.08% (30 runs sampled)
looksSame same x 1.08 ops/sec ±3.76% (25 runs sampled)

Contributing

brew install imagemagick@6 graphicsmagick
yarn
yarn test:watch

License

MIT