Image\PerceptualHash

NAME

Image\PerceptualHash - Generate comparable hash from images

SYNOPSIS

<?php
use Image\PerceptualHash;
use Image\PerceptualHash\Algorithm\DifferenceHash;
use Image\PerceptualHash\Algorithm\PerceptionHash;

// Create an instance of Image\PerceptualHash, at the same time calculate hashes
// using hashing algorithm Image\PerceptualHash\Algorithm\AverageHash by default
$ph = new PerceptualHash('/path/to/foo.jpg');

// Get binary hash
$binary_hash = $ph->bin();

// Get hexadecimal hash
$hex_hash = $ph->hex();

// Compare with another image, return a Hamming distance
$distance = $ph->compare('/path/to/bar.jpg');

// Calculate a similarity
$similarity = $ph->similarity('/path/to/baz.jpg');

// Calculate by other hashing algorithms
$ph = new PerceptualHash('/path/to/foo.jpg', new DifferenceHash());
// or
$ph = new PerceptualHash('/path/to/foo.jpg', new PerceptionHash());

DESCRIPTION

Image\PerceptualHash generates distinct, but not unique fingerprint with three hashing algorithms. Unlike cryptographic hashing, these fingerprints from similar images will be also similar.

INSTALLATION

To install this package into your project via composer, add the following snippet to your composer.json. Then run composer install.

"require": {
    "travail/image-perceptualhash": "dev-master"
}

or

"repositories": {
    {
        "type": "vcs",
        "url": "git@github.com:travail/php-Image-PerceptualHash.git"
    }
}

DEPENDENCIES

• ext-gd

METHODS

public __construct($file, Algorithm $algorithm)

Creates a new instance of Image\PerceptualHash and calculates hashes.

$file

Path to a file or a resource of that.

Algorithm $algorithm

Hashing algorithm, currently the following algorithm are available:

• AverageHash
• DifferenceHash
• PerceptionHash

public bin()

Returns calculated binary hash.

public hex()

Returns calculated hexadecimal hash.

public compare(mixed $file)

Compares with another image and returns the Hamming distance to that.

$file

Path to a file or a resource of that.

public similarity(mixed $file)

Calcuates the similarity to another image.

$file

Path to a file or a resource of that.

AUTHOR

travail

LICENSE

This library is free software. You can redistribute it and/or modify it under the same terms as PHP itself.