crop.pl

#!perl
use strict;
use warnings;
use Imager;
use File::Basename;

my $dir = shift;
my $savedir = "$dir/cropped";
-r $savedir or mkdir $savedir;
for my $subdir (glob("$dir/*")) {
    my ($number_base) = basename($subdir) =~ /(\d+)$/;
    $number_base ||= 0;
    my @pages = sort {
        $a->[1] <=> $b->[1]
    } map {
        my ($number) = $_ =~ /(\d+)\.jpeg/;
        $number ||= 0;
        $number += $number_base;
        [ $_ => $number ] 
    } glob "$subdir/*.jpeg";

    for my $page (@pages) {
        my ($file, $number) = @$page;
        my $image = Imager->new(file => $file);
        my $width = $image->getwidth;
        my $height = $image->getheight;
        my $target = int(232/182 * $width * 0.98);
        my $cropped = $image->crop(
            top => $number%2 ? $height - $target : 0, 
            height => $target
        );
        $cropped->write(file => "$savedir/$number.jpg") or die $cropped->errstr;
    }
}