quickly create a blank (white) image of the same size as a reference image passed in on the command line

make-blank.pl

#!/usr/bin/perl

# requires imagemagick to be installed on the system for 'identify' and 'convert'

use strict;
use warnings;

my $infile = shift;
my $color = shift;

die "usage: $0 <infile> [<color>, e.g. white or \"#abcdef\" (with quotes)]\n\n" unless (defined($infile));

$color = "white" unless defined($color);

my $identify_output = `identify $infile`;

if ($identify_output =~ m{^(.*?)\.(png|jpe?g|gif)(?:\[\d+\])?\s+(?:png|jpe?g|gif)\s+(\d+)x(\d+)\D}i) {
    my ($fileroot,$fileext,$x,$y) = ($1,$2,$3,$4);
    my $outfile = "$fileroot-blank.$fileext";
    die "error: will not overwrite existing file [$outfile]\n\n" if ( -e "$outfile");
    `convert -size ${x}x$y xc:$color -geometry ${x}x$y $outfile`;
}