Imagick::separateImageChannel

Separates a channel from the image and returns a grayscale image. A channel is a particular color component of each pixel in the image.

Which 'channel' to return. For colorspaces other than RGB, you can still use the CHANNEL_RED, CHANNEL_GREEN, CHANNEL_BLUE constants to indicate the 1st, 2nd and 3rd channels.

Returns TRUE on success.

Throws ImagickException on error.

<?php
function separateImageChannel($imagePath, $channel) {
    $imagick = new \Imagick(realpath($imagePath));
    $imagick->separateimagechannel($channel);
    header("Content-Type: image/jpg");
    echo $imagick->getImageBlob();
}

separateImageChannel($imagePath, \Imagick::CHANNEL_GREEN);

?>