#! perl -slw
use strict;
use GD;

my $img = GD::Image->newFromJpeg( $ARGV[ 0 ], 1 )
    or die "$ARGV[ 0 ] : $!";

my( $width, $height ) = $img->getBounds();

( my $bmpFile = $ARGV[ 0 ] ) =~ s[.jpg$][.bmp]i;
open BMP, '>:raw', $bmpFile or die "$bmpFile : $!";
binmode BMP;

printf BMP '%s', pack 'A2ISSI', 'BM', $width * $height +54, 0, 0, 54;

printf BMP '%s', pack 'IiiSSIIiiII',
    40, $width, $height, 1, 24, 0, $width * $height, 11811, 11811, 0, 0;

for my $y ( reverse 0 .. $height-1 ) {
    for my $x ( 0 .. $width-1 ) {
        printf BMP '%s', pack 'CCC', reverse $img->rgb( $img->getPixel( $x, $y ) );
    }
}
close BMP;