Resize all images in a directory. Images should be of the format xxx_WIDTHxHEIGHT.ext, so bla_2048x1536.png, run as : ./cut50.pl 2048 1536 and all images are resized to 1024x768.

gistfile1.pl

#!/usr/bin/perl 

$x = $ARGV[0];
$y = $ARGV[1];

if (not $x or not $y) {
        print "./cut50.pl width height\n"; 
        exit;
} 

$fv = "_$x"."x"."$y"."\\.";

$nx = int($x / 2);
$ny = int($y / 2);

foreach(glob("*.*")) {
 chomp;
 $f = $_; 
 next if not /$fv/;
 /^(.*?)$fv(.*)$/;
 $nn = $1."_".$nx."x".$ny.".".$2;

 print `convert "$f" -resize 50% "$nn"`;
}