Hi, I have some code which directly captures images from a bt848 camera. It works OK. In the below code, the captured image is pnm, but it is in BGR format, so I need to reopen it with the Imager module, and use it's cool matrix method to convert it to RGB. Now my question is this: How can avoid writing the file twice to disk? First V4L writes a pnm, then I have to reopen the pnm with Imager.

I tried to change the output filehandle for the v4l pnm to a scalar string(I'm using 5.8), so instead of opening a file, I opened \$temp. That goes OK, but when I try to use Imager to open \$temp, it just dies and dumps \$temp to STDERR.

So is it possible to somehow pass \$temp to Imager? 

#!/usr/bin/perl
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 $fr now, as it contains the raw BGR data 
        open (JP,">z$count.pnm") or die $!;

        #my $temp=''; #this fails when passing to Imager
        # open (JP,">",\$temp)or die $!; 

        print JP "P6\n320 240\n255\n";  #header 
        print JP $nfr;
        close JP;

       # convert bgr to rgb 
       my $img = Imager->new();
       $img->open(file=>"z$count.pnm", type => 'pnm') or die $img->err
+str();
       my $newimg = $img->copy();
          $newimg = $img->convert(matrix=>[ [ 0, 0, 1 ],
                                            [ 0, 1, 0 ],
                                            [ 1, 0, 0 ] ]);
       $newimg->write(file=>"z$count.jpg", type=>'jpeg')
                          or die $img->errstr;

     }

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

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update (broquaint): added <readmore> tag

In reply to Using IO::String with a module by zentara

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