Imagick – Generate Preview Image of PDF

<?php

$file          = get_attached_file( $attachment_id );
$output_format = "jpeg";
$antialiasing  = "4";
$preview_page  = "1";
$resolution    = "300";
$output_file   = 'srv/www/chetan/doc/' . $attachment_id . '_imagick_preview.jpg';
$exec_command  = "gs -dSAFER -dBATCH -dNOPAUSE -sDEVICE=" . $output_format . " ";
$exec_command  .= "-dTextAlphaBits=" . $antialiasing . " -dGraphicsAlphaBits=" . $antialiasing . " ";
$exec_command  .= "-dFirstPage=" . $preview_page . " -dLastPage=" . $preview_page . " ";
$exec_command  .= "-r" . $resolution . " ";
$exec_command  .= "-sOutputFile=" . $output_file . " '" . $file . "'";

exec( $exec_command, $command_output, $return_val );