miniatura.php

<?php
    $imagem=imagecreatefromjpeg("IMAGEM.jpg");
    $im=imagecreatetruecolor(150,150);
    list($w,$h)=getimagesize("IMAGEM.jpg");
    $x0=($w-(0.8*$h))/2;
    $y0=0.1*h;
    imagecopyresized($im,$imagem,0,0,$x0,$y0,150,150,0.8*$h,0.8*$h);
    imagejpeg($im,"miniatura.jpg");
?>