FFmpeg Image Diff

A NodeJS image diffing library using
FFmpeg.
Creates an image showing perceptual differences and returns
SSIM data.

Contents

- Requirements
- Install
- Usage
- Options
- ssim
- similarity
- blend
- opacity
- color
- Samples
- Reference image
- Comparison image
- Output image
- Testing
- License
- Author

Requirements

This is a thin wrapper around FFmpeg and has no other
dependencies.

Install

``sh
npm install ffmpeg-image-diff
`

Usage

Displaying SSIM data
only:

`js
const imgDiff = require('ffmpeg-image-diff')

imgDiff(
referenceImage, // e.g. 'test/lenna.png'
comparisonImage // e.g. 'test/lenna-edit.png'
)
.then(ssim => {
// Sample output: { R: 0.990149, G: 0.991289, B: 0.990579, All: 0.990672 }
console.log(ssim)
})
.catch(error => {
console.error(error)
})
`

Creating a differential image with default options:

`js
const imgDiff = require('ffmpeg-image-diff')

imgDiff(
referenceImage, // e.g. 'test/lenna.png'
comparisonImage, // e.g. 'test/lenna-edit.png'
outputImage, // e.g. 'test/out.png', overwrites an existing file
{
ssim: true, // true or false
similarity: 0.01, // 1.0 - 0.01
blend: 1.0, // 1.0 - 0.0
opacity: 0.1, // 1.0 - 0.0
color: 'magenta' // magenta, yellow, cyan, red green, blue or ''
}
)
.then(ssim => {
// Sample output: { R: 0.990149, G: 0.991289, B: 0.990579, All: 0.990672 }
console.log(ssim)
})
.catch(error => {
console.error(error)
})
`

Options

$3

If set to false, disables
SSIM calculation.
_Default:_ true

$3

Defines the threshold to identify image differences.
0.01 matches slight differences, while 1.0 only matches stark contrast.
_Range:_ 1.0 - 0.01
_Default:_ 0.01

$3

Blend percentage for the differential pixels.
Higher values result in semi-transparent pixels, with a higher transparency the
more similar the pixels color is to the original color.
_Range:_ 1.0 - 0.0
_Default:_ 1.0

$3

Opacity of the reference image as backdrop for the differential image.
Higher values result in a more opaque background image.
_Range:_ 1.0 - 0.0
_Default:_ 0.1

$3

The color balance of the differential pixels.
An empty string displays the default differential pixels.
_Set:_ ['magenta', 'yellow', 'cyan', 'red', 'green', 'blue', '']
_Default:_ 'magenta'

Samples

$3

!Lenna

$3

!Lenna Edit

$3

!Lenna Diff

Testing

1. Start Docker.
2. Install development dependencies:
`sh
npm install
`
3. Run the tests:
`sh
npm test
``

License

Released under the MIT license.

Author

Sebastian Tschan