PHP | Imagick getImageSignature() Function

The Imagick::getImageSignature() function is an inbuilt function in PHP which is used to generate an SHA-256 message digest for an image.

Syntax:

string Imagick::getImageSignature( void )

Parameters: This function does not accept any parameter.

Return Value: This function returns a string of SHA-256 hash of the file.

Below programs illustrate the Imagick::getImageSignature() function in PHP:

Program 1:
Original Image:

<?php

// PHP program to illustrate getImageSignature function
$image = new Imagick(
"https://media.geeksforgeeks.org/wp-content/uploads/geeksforgeeks-15.png");

// Using getImageSignature function
$pixels = $image->getImageSignature();

print($pixels);
?>

Output:

f64054f5bcb4cfb82c6126eff6d3d4e6be7d0e72d5620033442cecb4b9feabbd

Program 2:
Original Image:

<?php

$string = "Computer Science portal for Geeks!";

// Creating new image of above String
// and add color
$im = new Imagick();
$draw = new ImagickDraw();

// Fill the color in image
$draw->setFillColor(new ImagickPixel('green'));

// Set the text font size
$draw->setFontSize(50);

$metrix = $im->queryFontMetrics($draw, $string);
$draw->annotation(0, 40, $string);
$im->newImage($metrix['textWidth'], $metrix['textHeight'],
        new ImagickPixel('white'));
// Draw the image
$im->drawImage($draw);
$im->setImageFormat('jpeg');

// Using getImageSignature function
$pixels = $im->getImageSignature();

print($pixels);
?>

Output:

ed79035e13153385c344d19586e98941dd336165a3ca486200097c0bd2f4188c

Reference: http://php.net/manual/en/imagick.getimagesignature.php