Well I don't know how simpler you can get than what you've already posted/said.
Photos
The perl/Tk Photo() function achieves an effect similar to the Bitmap() function. Namely, it returns a file descriptor to be used in a later -image configuration option to a widget.
As an example consider the Label widget that uses the 'imggif' descriptor in the following:
Code:
#!/usr/bin/perl -w
use strict;
use Tk;
my $main = new MainWindow;
$main->Photo(
'imggif'
, -file => "$Tk::tk_library/demos/images/earthris.gif"
);
my $c = $main->Label( '-image'=>'imggif' )->pack;
$main->Button(
-text => 'exit',
-command => sub{destroy $main}
)->pack(-anchor => 'e');
MainLoop;
img/photo_earthris.gif