Convert GD image back to binary data

Question

I have a GD image resource created from imagecreatefromstring. After some image operations, I want to convert it back to binary data. How would I do this? Can't see any functions in the manual...

Answer 1

Use imagejpeg, imagepng, or similar. Use output buffering if you want to dump the result to a string, rather than a file:

ob_start();
imagejpeg($im);
$image_string = ob_get_contents();
ob_end_flush();

Answer 2

function image_data($gdimage)
{
    ob_start();
    imagejpeg($gdimage);
    return(ob_get_clean());
}