This is a PHP extension builder for libpuzzle.

Install php-dev and libpuzzle from your package manager (apt install php-dev libpuzzle-dev for example)

Here are the basic steps in order to install the extension:

cd src
phpize
./configure --with-libpuzzle
make clean
make
make install

If libpuzzle is installed in a non-standard location, use: ./configure --with-libpuzzle=/base/directory/for/libpuzzle

Then edit your php.ini file and add:

extension=libpuzzle.so

Usage

The PHP extension provides bindings for the following tuning functions:

puzzle_set_max_width()
puzzle_set_max_height()
puzzle_set_lambdas()
puzzle_set_noise_cutoff()
puzzle_set_p_ratio()
puzzle_set_contrast_barrier_for_cropping()
puzzle_set_max_cropping_ratio()
puzzle_set_autocrop()

Have a look at the puzzle_set man page for more info about those.

Getting the signature of a picture is as simple as:

$signature = puzzle_fill_cvec_from_file($filename);

In order to compute the similarity between two pictures using their signatures, use:

$d = puzzle_vector_normalized_distance($signature1, $signature2);

The result is between 0.0 and 1.0, with 0.6 being a good threshold to detect visually similar pictures.

The PUZZLE_CVEC_SIMILARITY_THRESHOLD, PUZZLE_CVEC_SIMILARITY_HIGH_THRESHOLD, PUZZLE_CVEC_SIMILARITY_LOW_THRESHOLD and PUZZLE_CVEC_SIMILARITY_LOWER_THRESHOLD constants can also be used to get common thresholds :

if ($d < PUZZLE_CVEC_SIMILARITY_THRESHOLD) {
  echo "Pictures look similar\n";
}

Before storing a signature into a database, you can compress it in order to save some storage space:

$compressed_signature = puzzle_compress_cvec($signature);

Before use, those compressed signatures must be uncompressed with:

$signature = puzzle_uncompress_cvec($compressed_signature);

benjaminjonard/libpuzzle-php-extension-builder

This is a PHP extension builder for libpuzzle.

Usage