#!/usr/bin/perl
use warnings;
use strict;
use Tk;
use Tk::JPEG;

my $file   = "zen16.jpg";
my $mw  = Tk::MainWindow->new;
my $can = $mw->Canvas( -width => 320, -height => 240 )->pack();

# if you are pulling your image from data (inline base64encoded string
# you may need to specify -format
#my $img = $mw->Photo( -data => $data, -format => 'jpeg' );

my $img = $mw->Photo( -file => $file);
$can->createImage( 0, 0, -image => $img, -anchor => 'nw' );

my $red = $can->createRectangle(0, 20, 50, 75, -fill => 'red');

$can->Tk::bind("<Button-1>", [ \&print_xy, Ev('x'), Ev('y') ]);

MainLoop();

sub print_xy {
 # print "@_\n";
  my ($canv, $x, $y) = @_;
  print "(x,y) = ", $canv->canvasx($x), ", ", $canv->canvasy($y), "\n";
  printf "%6.6X\n", $img->get($canv->canvasx($x), $canv->canvasy($y) );
}