Wednesday, October 29, 2008

My Dot Pattern

Here are my dots. Can you see the pattern?

Lexmark C530 Serial Number 9416FX1 (rendered in Photoshop to show dots visibly)

It's ridiculously obvious. Here are some rectangles colored over the pattern:

This really makes the pattern pop out. The dots are in a 21x8 matrix. The pattern is always the same - patterns from previous prints are identical to this scanned and rendered image. Therefore, it's impossible that date information is encoded into the pattern on Lexmark printers, just serial numbers.

I was on campus today, and found two more Lexmark color laser printers.

Lexmark C752 - Serial Number 940FNX2 (rendered in Photoshop to show dots visibly)

The green boxes are separate occurrences of the pattern; they cover the entire page just like my printer.

It's harder to see dots on this page because the print quality was poor; I am sure both of these campus printers have printed thousands more sheets than mine. Because the clarity of the pattern varied, I had to draw a massive grid to make sure I wasn't missing any dots from one square to the next. I was careful to ignore "noise" and only focus on repeating dots.

Lexmark C760 - Serial Number 940KG8H (rendered in Photoshop to show dots visibly)

I put everything into Excel to try and make sense of the patterns:

I'm temped to think that since the grid is 21x8 on all printers, and each serial number is seven characters, that each character is encoded by three columns of the pattern. For example, because the first six columns are identical on all three of the printers I've tested, the first three columns could mean "9" and the next three could mean "4".

I haven't had the time to really thoroughly check it out, but here's the information for the world to see.

Lexmark's Reply: The Escalation

I got an email back today from the same eSupport representative at Lexmark. Here is what it said:

Dear Brahm,

Thank you for continuing to use our e-mail service.

My higher level support requires a physical copies of the Menu Setting Pages and the Print Quality Pages. Please send it to the following address.

Please don't forget to put the service request number {removed}.

Lexmark International
740 West New Circle Road
Dept 504J44L
BLD 4-2
Lexington, KY 40550
Attraction "{removed}"
Airborne on account #

Please follow the steps to print the Menu Setting Pages and the Print Quality Pages.

To Print The Menus Setting Pages,

{removed - long & boring}

To Print The Print Quality Pages:

{removed - long & boring}

Here is your Service Request # 1-

If you have any more questions or concerns, please contact me at your convenience and I will be happy to assist you. (If I am not available, another representative may reply to your request.)

Lexmark eSupport Team

The next step for me will be to put together a package to Lexmark, and carefully document when I'm sending. I will get that done within the next two days or so and fire it off to the customer service team in Kentucky. Maybe I will CC some test pages to the EFF while I'm at it.

Monday, October 27, 2008

The Reply.

Okay, this is the first post I have actually completed in "real time". The rest of the entries were just getting caught up on what I've done over the last day or two.

I just finished composing the following email to my Lexmark eSupport rep. I did my best to be polite, concise, and comprehensive.

Hi {removed},

Thank you for your reply. I have followed your instructions exactly (and have even done some additional troubleshooting), but the tiny near-invisible matrix of yellow dots appears on printed documents regardless. I do NOT think this is an issue with toner cartridges or photoconductor units, but I will leave that for someone else to judge.

Here are the steps I have completed:

0. Before swapping any Photoconductor units, I printed a test page from the Print Quality Pages menu, and scanned it at high resolution. I've attached a file that demonstrates this: procedure_experiment0.jpg. This cropped image is the printer's serial number, and is my "control group".

1. I swapped the Yellow and Magenta Photoconductor units as per your instructions. I printed a second set of Print Quality Pages and scanned the results again, please see procedure_experiment1.jpg.

2. After swapping the Yellow and Magenta Photoconductors, the color did not change to Magenta.

3. Since the color did not change, I can safely conclude that the Photoconductor unit is not defective, based on your information.

4. Even though, according to the above test, the Photoconductor units are not defective, I have included the part numbers for your reference:
C53030X (4 units)
Serial numbers: CAS0633253B3 (Y), CAS0633253C7 (C), CAS0633253C4 (M), CAS063325397 (Black).

5. You said that if the Photoconductor swap didn't work, the toner must be defective. I decided to swap the Magenta and Yellow Toner Cartridges to see if this was true. When I printed a third set of Print Quality Pages, the dots had changed from Yellow to Magenta (see procedure_experiment2.jpg).

Therefore, either BOTH cartridges are defective, or the problem is something else. I would be willing to confirm this with the cyan and black cartridges, if need be.

Yellow Cartridge - C5220YS, Serial CAA080421969
Magenta Cartridge - C5220MS, Serial CAA080585567

I have attached scans of the menu settings pages as per your request. There is adequate toner to complete any print job.

Here is my contact information:
Name: Brahm {removed}
Contact Number: {removed}
Business/Company Name: N/A - the printer was purchased for home office use.
Street Address: {removed}

I would like to re-link you to the Electronic Frontier Foundation's research on the "yellow dots":

If the yellow dots are a result of a security measure implemented by Lexmark, I would appreciate acknowledgment of the fact. Is there is an option to disable the forensic tracking dots? If not, is there a software update that will allow me to do this? If there is no software update yet, is there one in development? Are there Lexmark printers that do not print these dots, and is it possible arrange an exchange for such a model?

I appreciate your assistance in this matter, and sincerely thank you for the time you have dedicated to my inquiry so far!

To be truthful, I do not know what to expect for a response.

I may receive additional technical support - for example "take out the toner and shake it". That's fine and I will play along, but I am extremely doubtful of that working at this point. I would like this issue of consumer rights (knowing what security mechanisms are present in a product you purchase) are present, and how they affect my privacy.

I may receive information about an exchange. It's theoretically possible I can exchange this model for one without forensic tracking dots, but doubtful. Were I to receive another yellow-dot printer in the mail, I would have to start from square one.

I may receive no response. I might "know too much". If that's the case, it's time to write my polite letter of complaint to their customer services, privacy officer, or whomever it is applicable to. If that fails, there is always the Executive Email Carpet Bomb.

The best case is a response that will explain how to disable these dots. Somehow... I feel that is too much to hope for.

The Procedure.

Anyone who knows me will know that science is a pretty big part of my life. It would be important to catalog Lexmark's requests so that I could repeat any experiment if need be and produce the same results.

Before completing Step 1 (swap Yellow and Magenta photoconductor units), I decided it would be best to perform a control experiment. I printed the Print Quality pages with a completely default setup:

Figure 1: Control Print, Default Setup (click for large). As you can see, with a bit of tweaking in Photoshop, the dots pop out and are quite visible.

Next, I followed Lexmark's instructions and swapped the Yellow Photoconductor unit for the Magenta Photoconductor unit. The photoconductor is the unit of the laser printer that aborbs the laser light and causes the toner to react. Here are my photoconductors:

Figure 2: My Photoconductor units. The serial numbers are all visible, should you choose to enlarge this image!

Lexmark predicted that if the yellow dots had been caused by a defective photoconductor unit, the dots would now appear megenta. Here are the results:

Figure 3: Photoconductor swap results. The yellow dots are still present, and have not turned magenta. According to Lexmark, the "problem" is not the photoconductor unit!

The support email goes on to say that "If the issue stays with the same Yellow then the Toner Cartridge is defective, the Toner Cartridge needs to be replaced to fix the issue." Luckily, there is an easy way to prove this hypothesis wrong: swap the toner cartridge.

I swapped the yellow and magenta toner cartridges. Here is a picture of the swap:

Figure 4: The yellow and magenta toner cartridges have been swapped.

Any predictions for what will happen?

Figure 5: A scan of the Print Quality Page after the yellow and magenta toner cartridges have been swapped. Note that tiny magenta dots are clearly visible everywhere on the page! This image has not been manipulated, except to crop it to a smaller size.

By Lexmark's definition, BOTH of my yellow and magenta toner cartidges appear to be "defective". I wonder what would happen if I tested my black and cyan cartidges in a similar manner... I am sure they will be "defective" as well.

  • Yellow dots are NOT dependent on a photoconductor unit.
  • Dots appearing are NOT dependent on what color toner cartridge is inserted.
  • Dots WILL appear from whatever cartridge is inserted in the yellow toner's spot, on any color document printed.
  • There is NO WAY to disable the yellow dots in any Lexmark menu or manual.
  • Based on information collected from other websites, it has been proven these dots contain information like your printer's serial number, and the date and time your document was printed.
Here is the last piece of information Lexmark wanted - my Menu Page Settings reports. I've inlcuded them here for the internet's reference.

Figures 6, 7, 8: Printer Settings.

Next step: The Reply.

The Email.

I figured that after confirming of the presence of the yellow dots, I could email Lexmark and ask them what the deal was. I sent them the following email through their generic customer support page:


My printer prints a matrix of yellow dots over everything I print, and I cannot disable this "feature". After some web searching, I've found that the dots appear to be intentional:

I have a few photos I snapped of this that I can email if required.

I have two questions:
1) Can I disable the yellow dots?
2) Why are they there in the first place?

Thank you!

I figured that they would take me at my word. Here is the response I received:

Dear Brahm,

Thank you for contacting Lexmark email support. I would like to assist you in this regard.

As I understand from your mail that the Lexmark C530 printer is exhibiting print quality issue. For which the main cause of the issue could be with the Photoconductor Unit or the Toner Cartridge. In order to figure out which of the part is causing the issue, please follow the troubleshooting steps given below.

1. Please swap the Yellow Photoconductor Unit with the Magenta Photoconductor Unit and print the Print Quality Pages.
To Print The Print Quality Pages:
a: Power the printer off.
b: While holding down both Check Mark & Right Arrow button and the button on the printer's operator panel, power the printer back on.
c: When you see Performing Self Test or the clock graphic on the printer display, release both buttons.
d: Use either the Top Arrow Button or Down Arrow Button on the printer operator panel to scroll through the various menu options until you see Select Print Quality Pages (or Select Prt Quality Pages) on the printer display.
e: Press the Select button or Check Mart Button to initiate the printing of the quality pages. When the pages have finished printing, Select Print Quality Pages (or Select Prt Quality Pages) should once again appear on the printer display.

2. Check whether after swapping the photoconductor Unit, does the color changes to Magenta.

3. If it changes to the Magenta then the photoconductor Unit is defective. The Photoconductor Unit has to be replaced to fix the issue.

4. Please get back with the photoconductor Unit Part Number and barcode Number (found on the Photoconductor Unit).

5. If the issue stays with the same Yellow then the Toner Cartridge is defective, the Toner Cartridge needs to be replaced to fix the issue. Please get back with the Toner Cartridge Part Number and the barcode Number (found on the Toner Cartridge).

Please print out a Menu settings page to identify the supply level. To do so follow the steps to print the Menu Settings Pages below:

1. Make sure the printer is turned on and in the Ready state.
2. Scroll in the menu till you find Reports.
3. Press select and under this menu search for Menu Settings Page.
4. Press select again to print the pages.

Please get back with results and the following information,

First Last Name
Contact Number
Business/Company Name
Street Address Where Printer Is Located With The Postal/Province Code

Here is your Service Request # {removed}

If you have any more questions or concerns, please contact me at your convenience and I will be happy to assist you. (If I am not available, another representative may reply to your request.)

Lexmark eSupport Team
[THREAD ID:{removed}]

To make a long story short, the issue at hand of yellow tracking dots was ignored, and I am required to jump through several technical troubleshooting hoops before I can make a more extensive claim that my printer does, in fact, encode forensic tracking dots on everything I print! But I WILL cooperate, in the interest of my own privacy and consumer rights!

Next step: The Procedure.

The Evidence.

Digital camera in hand, I snapped a few shots of a Windows Printer Test Page using the digital macro function for the extreme closeups. Here is what I found:

Gasp! It's those tiny yellow dots.

They're a bit hard to see, but one trick the EFF recommends is to shine a blue LED on the page, to make them "pop".

You can see these dots are one pixel, and printed extremely lightly. How many people with color printers are aware their printers are encoding information about WHEN and WHERE they print onto every page?

It begins!

Hi. My name is Brahm. I own a Lexmark C530dn printer. I bought it in the summer of 2007 from the Campus Computer Store at the University of Saskatchewan. It's an excellent color laser printer, and I really like it, but I have one problem - it prints a near-invisible matrix of yellow dots on everything I print.

I read about the dots, and read something crazy: that the dots could be used to encode information into every page you print, like the time and date you printed the document, and the serial number of your printer.

Not a big deal, right? This issue has huge implications on customer privacy. Imagine if every document you ever printed could be traced back to you - every resume, every letter, every assignment, every government document printed online. It would be equivalent to if every dollar you ever spent could be traced back to you, or if any act you ever committed anonymously could be traced back to you. It's an invasion of privacy, and a violation of free speech by losing the ability to communicate with anonimity.

I feel that, in terms of my printing habits, I have nothing to hide, and will be updating with blog with "sensitive" information about my printer without hesitation. This includes my printer's serial number, which happens to be 9416FX1.

These webpages were my two starting links:
Electronic Frontier Foundation -
Massachusetts Institute of Technology -

I'm starting this blog to document my experiences in contacting Lexmark customer support, or any additional information I stumble across. Please feel free to email me at or leave a comment on this blog!