After a bit of tinkering and bugfixing, the solution is:

#!/usr/bin/env perl

use strict;
use warnings;

use Text::QRCode;

my $qr = Text::QRCode->new()->plot("YAPH");

my $pixelsize = 15;
print '<table border="0" cellspacing="0" cellpadding="0">', "\n";
my $firstline = 1;
my $saved = 0;
foreach my $line (@{$qr}) {
    print "<tr>";
    my $firstelem = 1;
    my $width = 0;
    my $color = '';
    my $firstblockinline = 1;
    foreach my $elem (@{$line}) {
        if($firstline) {
            # First line, no compression. This sets the correct column
+ width for all columns
            my $realcol = mapColor($elem);
            print '<td width="' . $pixelsize . 'px" height="' . $pixel
+size . 'px" bgcolor="' . $realcol . '"></td>';
        } else {
            if($firstelem) {
                $color = $elem;
                $width = 1;
                $firstelem = 0;
            } else {
                if($color eq $elem) {
                    $width++;
                    $saved++;
                } else {
                    my $realcol = mapColor($color);
                    print '<td colspan="' . $width . '" ';
                    if($firstblockinline) {
                        print 'height="' . $pixelsize . 'px" ';
                        $firstblockinline = 0;
                    }
                    print 'bgcolor="' . $realcol . '"></td>';
                    $color = $elem;
                    $width = 1;
                }
            }
        }
    }
    if(!$firstline) {
        # print last element of the current line
        my $realcol = mapColor($color);
        print '<td colspan="' . $width . '" height="' . $pixelsize . '
+px" bgcolor="' . $realcol . '"></td>';
    }
    print "</tr>\n";
    $firstline = 0;
}
print '</table>', "\n";
print '<!-- run length compression saved ', $saved, ' table fields-->'
+, "\n";

sub mapColor {
    my ($inval) = @_;

    if($inval eq '*') {
        return 'black';
    }
    return 'white';
}
[download]

Which means i can turn it into this:

#!/usr/bin/env perl

use strict;
use warnings;

use GD;
my $img = GD::Image->newFromPng('tentacle.png', 0);
my ($w, $h) = $img->getBounds();


my $pixelsize = 15;
print '<table border="0" cellspacing="0" cellpadding="0">', "\n";
my $saved = 0;
for(my $y = 0; $y < $h; $y++) {
    print "<tr>";
    my $firstelem = 1;
    my $width = 0;
    my $color = '';
    my $firstblockinline = 1;
    for(my $x = 0; $x < $w; $x++) {
        my $index = $img->getPixel($x, $y);
        my ($r,$g,$b) = $img->rgb($index);
        my $elem = sprintf("#%02X%02X%02X", $r, $g, $b);
        if(!$y) {
            # First line, no compression. This sets the correct column
+ width for all columns
            print '<td width="' . $pixelsize . 'px" height="' . $pixel
+size . 'px" bgcolor="' . $elem . '"></td>';
        } else {
            if($firstelem) {
                $color = $elem;
                $width = 1;
                $firstelem = 0;
            } else {
                if($color eq $elem) {
                    $width++;
                    $saved++;
                } else {
                    print '<td colspan="' . $width . '" ';
                    if($firstblockinline) {
                        print 'height="' . $pixelsize . 'px" ';
                        $firstblockinline = 0;
                    }
                    print 'bgcolor="' . $color . '"></td>';
                    $color = $elem;
                    $width = 1;
                }
            }
        }
    }
    if($y) {
        # print last element of the current line
        print '<td colspan="' . $width . '" height="' . $pixelsize . '
+px" bgcolor="' . $color . '"></td>';
    }
    print "</tr>\n";
}
print '</table>', "\n";
print '<!-- run length compression saved ', $saved, ' table fields-->'
+, "\n";
[download]

Which results in the ability to display (low res) colorful images in PerlMonks, using nothing but allowed HTML tags:

<!-- run length compression saved 709 table fields-->

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