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Need help to decode HP color laser jet tracking dots

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Need help to decode HP color laser jet tracking dots Hatto von Hatzfeld 21 Feb 14:32
  Need help to decode HP color laser jet tracking dots Robert Smits 21 Feb 18:03
Hatto von Hatzfeld
2008-02-21 14:32:05 UTC (almost 17 years ago)

Need help to decode HP color laser jet tracking dots

If you have a HP Color Laser printer, I'd like to ask you a favour:

Probably you know this: When you print on a color laser printer, it's likely that you are also printing a pattern of invisible yellow dots. These dots enable law enforcement agencies, secret services and others to track the origin of the stuff you have printed (see http://seeingyellow.com/ and http://www.eff.org/issues/printers for more informations).

To be on topic in this mailing list: I wrote a small Gimp plug-in (i.e. a script-fu) which helps to identify such yellow dots: http://registry.gimp.org/node/623 (tests are appreciated).

I'd like to decode the yellow tracking dots printed by my HP Color 3700 (together with a guy from EFF), but I need the output of other HP printers (model 3700 and others) to do so. If you want to help me please send me dot patterns or scanned images. It will work best for me if you print just a few colored (!) words on a sheet, scan a small empty (i.e. white) part of that sheet (about 5 x 5 cm, scanned with at least 600dpi) and send the scan (or even better: the output of my script applied to the scan) to me, together with the model and the serial number (and possibly the formatter number) of that printer.

Thanks in advance, Hatto

Robert Smits
2008-02-21 18:03:39 UTC (almost 17 years ago)

Need help to decode HP color laser jet tracking dots

On February 21, 2008 05:32:05 am Hatto von Hatzfeld wrote:

If you have a HP Color Laser printer, I'd like to ask you a favour:

Probably you know this: When you print on a color laser printer, it's likely that you are also printing a pattern of invisible yellow dots. These dots enable law enforcement agencies, secret services and others to track the origin of the stuff you have printed (see http://seeingyellow.com/ and http://www.eff.org/issues/printers for more informations).

You probably know this isn't restricted to laser printers, but includes all colour copiers as well.