Thank You Zaxo, you answered 2 questions for the price of 1. :-) I was wondering how I could do the hex byte swap manually, with perl, and your pack-unpack method does work fine, but it is quite slow(plus Imager can convert to jpg). I played around some more, and found that I could save a little bit of processing by reversing the BGR string(which left it RGB but upside down and flipped :-)), then use Imager to do a hv flip. The advantge to this is I didn't need to make a copy of the imager object, since an hv flip can be done in-place on the object. The code I've settled on is below.

use warnings;
use strict;
use Video::Capture::V4l;
use Imager;

my $grab = new Video::Capture::V4l
   or die "Unable to open Videodevice: $!";

$|=1;
my $frame=0;
my $fr = $grab->capture ($frame, 320, 240);
my $count=0;

for(0..1) {
   my $nfr = $grab->capture (1-$frame, 320, 240);
   $grab->sync($frame) or die "unable to sync";

   unless($count == 0){
      # save $fr now, as it contains the raw BGR data 
        my $temp='';
        open (JP,'>',\$temp) or die $!;
        print JP "P6\n320 240\n255\n";  #header 
        $nfr = reverse $nfr;
        print JP $nfr;
        close JP;

        my $img = Imager->new();
        $img->read(data=>$temp,type =>'pnm')
                                 or warn $img->errstr();
        $img->flip(dir=>"hv");
        $img->write(file=>"z$count.jpg", type=>'jpeg')
                                 or warn $img->errstr;
   }

 $count++;
 $frame = 1-$frame;
 $fr = $nfr;
}
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