nbsbbs / phash
Counts perceptual hash of images
Requires
- php: >=7.4
- ext-gd: *
This package is auto-updated.
Last update: 2024-12-09 22:01:00 UTC
README
Perceptual hash implementation for PHP
This is my PHP Implementation of the AverageHash algorithm to create Perceptual Hashes
A perceptual hash is different from a typical hash as it allows you to compute a signature based on the visual features of an image rather than the actual data they contain as with a cryptographic hash. This allows you to use the Perceptual Hash for simple image matching which could prove useful in finding duplicate pictures or picture tagging.
To get a better understanding of this project see: http://www.hackerfactor.com/blog/index.php?/archives/432-Looks-Like-It.html
Sample Usage
You can use pHash methods as a class in your project and extend as you wish.
A basic implementation is as follows:
#sample implementation
$phasher = new Phash;
$phash2 = $phasher->getHash('phash2.jpg', false);
//this will echo hash in hex, then binary
echo $phasher->hashAsString($phash2, false).PHP_EOL;
echo $phasher->hashAsString($phash2).PHP_EOL;
$phash3 = $phasher->getHash('phash3.jpg', false);
//this will echo hash in hex, then binary
echo $phasher->hashAsString($phash3, false).PHP_EOL;
echo $phasher->hashAsString($phash3).PHP_EOL;
//using BIT COUNT METHOD FOR SIMILARITY
echo $phasher->getSimilarity($phash2, $phash3, 'BITS');
echo PHP_EOL;
//using HAMMING METHOD (DEFAULT) FOR SIMILARITY
echo $phasher->getSimilarity($phash2, $phash3);
echo PHP_EOL;
Notes
- The bitcount algorithm for matching similarity may be siginificantly faster than hamming distance.
- Calculating hamming distance between two hex based hashes may be faster but less accurate than the binary version