imagecopyresampled() works amazingly well, but here is something NOT to try with it:
The resize routine I wrote looks for pixel widths, and resizes images based on the notion that if their widths and heights are too big, so are their byte sizes. It worked out well at first.
But when I saw huge byte-size images slipping through beneath my 1000px-wide benchmark, I figured I'd subject the smaller-width images to resizing if their filesize() exceeded 100K.
The idea was that I'd "resize" them keeping their original widths and heights (i.e. in (1) below, $newW = $oldW, $newH = $oldH), and letting the "75" at (2) below reduce the byte size.
DON'T try that. imagecopyresampled() will lock up the server trying to resize an 800px-wide image to a "new" width of 800px. (I caught that on my Windows server before ever putting it on the destination Linux server, so take that with a grain of salt.)
I got around it by making $newW = ($picW * 0.99), etc. You get the byte-size reduction you want without locking up.
(1) imagecopyresampled($image_p, $image, 0, 0, 0, 0, $newW, $newH, $picW, $picH);
(2) imagejpeg($image_p, $theFile, 75);
