Example

function setImageChannelMask($image_path, $channel, $rotation_angle, $rotation_channel)
{
    $imagick = new \Imagick(realpath($image_path));
    $imagick->setImageChannelMask($channel);

    if ($rotation_channel === 0) {
        $imagick->rotationalBlurImage($rotation_angle);
    }
    else {
        $imagick->rotationalBlurImage($rotation_angle, $rotation_channel);
    }

    header("Content-Type: image/jpeg");
    echo $imagick->getImageBlob();
}