#!/usr/bin/perl
for my $file (@ARGV) {
    my $portrait = 0; # Portrait orientation?
    # Get dimensions of image file
    my $width = `identify -format %w $file 2>/dev/null` * 1.0;
    my $height = `identify -format %h $file 2>/dev/null` * 1.0;
    # Skip non-image files
    next if ($width <= 0) or ($height <= 0);
    if ($width < $height) {
	# Portrait orientation, change dimensions
	$portrait = 1;
	($width, $height) = ($height, $width);
    }
    my $ratio = $width/$height; # X/Y ratio of current image
    my $newratio = 3.0/2.0; # Desired X/Y ratio
    my $r = $ratio/$newratio;
    next if ($r < 1.01) and ($r > 0.99); # Skip image with desired X/Y ratio
    # Calculate new dimensions, store as integer
    my $newwidth = $width;
    my $newheight = sprintf("%d", $height*$r);
    my $xoffset = 0;
    my $yoffset = sprintf("%d", $height*(1-$r)/2.0);
    if ($portrait) {
	# Portrait orientation, change back the dimensions
	($width, $height) = ($height, $width);
	$newwidth = $newheight;
	$newheight = $height;
	$xoffset = $yoffset;
	$yoffset = 0;
    }
    # Do a loss-less JPEG cropping to the new dimensions
    system("jhead -cmd \"jpegtran -crop ${newwidth}x${newheight}+$xoffset+$yoffset &i > &o\" $file");
}