[Printers] HP Color Laserjet 2500 Results

[Patrick Burns]

Hi all.

I can confirm the HP Laserjet 2500 has tracking dots. I was surprised
that I could see the dots easily on my computer with a cheap scanner and
the GIMP.

Unfortunately the EFF pages don't have much information, so I wrote
something on my own experiences. URL is http://www.burnsonline.net/dots.
If anyone has any suggestions/corrections they would be greatly
appreciated.

It looks like the dot pattern is 18x22, but I really need to get the
serial number and analyse a few more pages before I can work out the
code. Assuming it's not encrypted or obfuscated somehow.

Still, it seems there's no need to hand-transcribe the dots if you have
a scanner and some image editing software. I'm sure some enterprising
person will be able to write some code to automatically extract the dots
from a scan and draw a grid over them. It seems like Ralf Muschall has
made a start.

-- 
  Patrick Burns
  pb at fusion.fastmail.fm