The imagecolorstotal() function gets the count of colors in an image's palette
Syntax
imagecolorstotal (img)
Parameters
img: Image created with imagecreatetruecolor().
Return
The imagecolorstotal() function returns the number of colors in an image palette.
Example
The following is an example
<?php
$img = imagecreatefromgif('https://www.tutorialspoint.com/images/html.gif');
echo 'Number of Colors = ' . imagecolorstotal($img);
imagedestroy($img);
?>Output
The following is the output:
Number of Colors = 128