<?php
//requires ImageMagick version 6.9.0-1 to have an effect on convolveImage
function setImageBias($bias) {
$imagick = new \Imagick(realpath("images/stack.jpg"));
$xKernel = array(
-0.70, 0, 0.70,
-0.70, 0, 0.70,
-0.70, 0, 0.70
);
$imagick->setImageBias($bias * \Imagick::getQuantum());
$imagick->convolveImage($xKernel, \Imagick::CHANNEL_ALL);
$imagick->setImageFormat('png');
header('Content-type: image/png');
echo $imagick->getImageBlob();
}
?>