Manipulating Image size.

[php-phan]

So i created a social network but one problem i have is when users upload an image it displays it at a fixed size like 250px x 250 px but some pictures have different dimensions so they look all messed up. Is there a way to manipute these pictures so they have like a max width and max hieght or something thatway they are all proportional....Thanks :-)

[NogDog]

<?php
$maxWidth = 250;
$maxHeight = 250;
$ratio = (($maxWidth / $maxHeight) > ($imageWidth / $imageHeight)) ? 
      $maxWidth / $imageWidth : $maxHeight / $imageHeight;
$displayWidth = (round($ratio * $imageWidth));
$displayHeight = (round($ratio * $imageHeight));