lib/gd.thumbnail.inc.php
Line 903:
function fastimagecopyresampled (&$dst_image, $src_image, $dst_x, $dst_y, $src_x, $src_y, $dst_w, $dst_h, $src_w, $src_h, $quality = 4)
// Optional "quality" parameter (defaults is 3). Fractional values are allowed, for example 1.5.
// 1 = Up to 600 times faster. Poor results, just uses imagecopyresized but removes black edges.
// 2 = Up to 95 times faster. Images may appear too sharp, some people may prefer it.
// 3 = Up to 60 times faster. Will give high quality smooth results very close to imagecopyresampled.
// 4 = Up to 25 times faster. Almost identical to imagecopyresampled for most images.
// 5 = No speedup. Just uses imagecopyresampled, highest quality but no advantage over imagecopyresampled.