kodus/image-hash

This library implements the aHash, dHash and pHash image-hashing algorithms as described in this article.

It's based on this implementation but with a loader-abstraction for GD and Imagick support, added tests, and a benchmark.

Usage

To compare two images:

use Kodus\ImageHash\ImageHasher;

$hasher = new ImageHasher();

$a_hash = $hasher->pHash("path/to/image-a.jpg");
$b_hash = $hasher->pHash("path/to/image-b.jpg");

if ($hasher->getDistance($a_hash, $b_hash) <= 2) {
    echo "same!";
} else {
    echo "different.";
}

Substitute calls to pHash() for aHash() or dHash() to use another algorithm, but note that getDistance() only makes sense for two hashes computed using the same algorithm.

Hashes are returned as a binary-mask string - use base_convert if you need a decimal or hex value.

Hacking

To run the tests:

php test/test.php

To run the benchmark:

php test/benchmark.php

If you hack on this library, be sure to run the benchmark before/after making changes.