When simply calling the Imagick class:
$image = new Imagick('/images/magick/atmsk.png');
I get the error message:
Fatal error: Uncaught exception 'ImagickException' with message 'unable to open file `/images/magick/atmsk.png' @ png.c/ReadPNGImage/2889' in .../imag.php:4 Stack trace: #0 .../imag.php(4): Imagick->__construct('/images/magick/...') #1 {main} thrown in .../imag.php
I have checked memory available as per another posting here and that is ok!
Use the full path to the image, for example:
$image = new Imagick($_SERVER['DOCUMENT_ROOT'] . '/images/magick/atmsk.png');