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14 years ago
If you care about speed, you probably already cache your generated images to a file. In that case, DON'T use "createimagefrompng" and "imagepng" to output the image. Use fpassthru instead. It is literally hundreds of times faster.

<?php
  header("Content-Type: image/png");
  
  # Generate cachefile for image, if it doesn't exist
  if( !file_exists($cachefile) ) {
    $im = generateimage();     # some code generates an image resource
    imagepng($im, $cachefile); # store the image to cachefile

    # don't output it like this:
    /* imagepng($im);*/
   
    imagedestroy($im);
  }

  $fp = fopen($cachefile, 'rb'); # stream the image directly from the cachefile
  fpassthru($fp);
  exit;
?>

I've tested it with a 5120x5120 (1.2Mb) image, that was cached on the harddisk. Using imagepng, the transfer took 12 seconds. Using fpassthru, it took only 32ms!
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