image-difference

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This is a fork of image-diff that is no longer maintained.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.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.
   • options.metric (String): Optional metric used for the computation of the output.
     • documentation
     • guide
     • implementation

Returns

Promise: Return the difference object with a total and percentage key.

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