The getImageSignature function for the ImageMagick package in PHP returns only the SHA-1 hash value for an image. There are not any other algorithms available for it within the ImageMagick package, but fortunately, this is PHP and you have a wide array of hashing algorithms to use on any image file. The function hash_algos() will return an array of hashing algorithms available in PHP and the function hash_file() will take three parameters (one for the algorithm to use, one for the filename, and an optional variable for binary output). Instead of being limited to the SHA-1 algorithm of the getImageSignature function, you could use SHA-256, SHA-384, SHA-512, Whirlpool, HAVAL, Salsa, Gost, Adler32, CRC32, or MD5, among others and variations of these.
However, the SHA-1 result of the hash_file() function performed on a file does not return the same result as the SHA-1 of the getImageSignature() function. This leads me to believe that the SHA-1 of the getImageSignature() might be performed on the Imagick object itself, instead of the file, whereas the hash_file() function is clearly performed on the file itself. That's just a guess, though.
Some sample code for the alternate hashing algorithm, with every algorithm performed on the image file :
$filename_with_folder_for_hashing = "image_workshop/test_file.bmp";
$php_dynamic_hash_algorithms = hash_algos();
$number_of_dynamic_hash_algorithms = count($php_dynamic_hash_algorithms);
for($i = 0; $i < $number_of_dynamic_hash_algorithms; $i++)
$current_hashing_algorithm = $php_dynamic_hash_algorithms[$i];
$current_hashing_algorithm_hex_result = hash_file($current_hashing_algorithm, $filename_with_folder_for_hashing, FALSE);
print("$current_hashing_algorithm Algorithm ::: $current_hashing_algorithm_hex_result");
md2 Algorithm ::: 03205df9c6717d74f1f003c66f58e98a
md4 Algorithm ::: b2a204a2e5c3968d2abd5dc372fbee10
md5 Algorithm ::: b9d92a61714b221d24c7730d4764ca82
sha1 Algorithm ::: 8db4c92346c26568b13ea43fbcf514e37942a41a
(and so on for 34 more algorithms)...