Image::ParseGIF would be used to present the progress bar, which is a "deanimated" GIF, not for parsing your original image. Click the given link, then click "browse", then click "examples" for a free progress bar GIF and some example scripts. It would go something like this:

for (my $p=0; $p<@pics; $p++){

  $img=Imager->new();   # create empty image

  my $gif = Image::ParseGIF->("progress.gif") 
  or die "failed to parse: $@\n";

  $gif->print_header;
  $gif->print_percent(0.00);

  $img->read(file=>$baseURL.$type.'/'.$pics[$p],type=>'jpeg') 
  or die $img->errstr();

  my $med   = $img->copy();
  my $thumb = $img->copy();

  $med = $img->scale(xpixels=>750);# sets width to 750px 
  $med->write(file=>$baseURL.$type.'/medium/'.$pics[$p]) 
  or die $image->errstr; # Write out image

  $gif->print_percent(0.10);    # 10% complete

  $thumb = $img->scale(ypixels=>150);# sets the height to 150px
  $thumb->write(file=>$baseURL.$type.'/thumbs/'.$pics[$p]) 
  or die $image->errstr; # Write out image

  $gif->print_percent(0.25);    # 25% complete

  my $rot90 = $img->rotate(degrees=>-90);
  $rot90->write(file=>$baseURL.$type.'/upright/'.$pics[$p]) 
  or die $image->errstr; # Write out image

  $gif->print_percent(0.70);    # 70% complete

  my @pic=split(/\./,$pics[$p]); # splits filename at dot [filename][j
+pg]
  $newDat.=$pic[0].'|';        # Used in a latter part of program 

  $gif->print_percent(1.00);    # done!
  $gif->print_trailer;
}
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