[Printers] Re: scanned images

[Patrick Murphy]

Hello B,

I went to your blog and had a look around.  Very interesting stuff!  Thanks for
posting the printer data you have.

I analyzed the DocuColor 12 images you provided in your blog post on Sept 6,
titled "More Scans".  Here is what I was able to extract:

====== DC12 SerNo 59046 at 19:00 ======
Serial number: 59046  Printed date: September 4, 2005 at 10:35 AM

====== DC12 SerNo 59046 at 19:01 ======
Serial number: 59046  Printed date: September 4, 2005 at 10:36 AM

====== DC12 SerNo 59987 at 18:50 ======
Serial number: 59987  Printed date: September 4, 2005 at 8:20 AM

====== DC12 SerNo 59987 at 18:51 ======
Serial number: 59987  Printed date: September 4, 2005 at 8:22 AM

====== DC12 SerNo 59987 at 18:53 ======
Serial number: 59987  Printed date: September 4, 2005 at 8:24 AM

====== DC12 SerNo 59987 at 18:54 ======
Serial number: 59987  Printed date: September 4, 2005 at 8:25 AM

As you can see, despite your initial doubt, the serial number is indeed
embedded in the image.  However, as you can also see, the date stamps match but
the time stamp I extracted does not match your time stamp.

I am virtually certain that I'm extracting the date and time values correctly. 
I'm wondering if the time has been set correctly on these printers.  If you
still have access to these DocuColor 12 printers, would it be possible to
confirm what time each printer thinks it is?

Regarding the HP 2600N info, the embedded data is in a different format.  I'm
working on a promising method to extract the information embedded in the image.
 It appears there are only 8 bytes of data, and the first 4 bytes are the same
between the two 2600N printers.  Here is the data I've extracted so far --
please note the bit order, nibble order and/or byte order may be reversed:

For HP 2600N, S/N CNBC55L0QJ, Formatter F9221M9:
  0xF0, 0xA5, 0x9C, 0x80, 0x01, 0x67, 0x10, 0xB7

For HP 2600N, S/N CNBC573058, Formatter F921F6L:
  0xF0, 0xA5, 0x9C, 0x80, 0x83, 0xC2, 0x50, 0xF8

This data agrees with additional bitwise checksum data that is also embedded,
which shows the 1s and 0s have been transcribed correctly.

I haven't yet been able to determine what this data means yet.  It would help
if I knew the date and time of printing for these images.  It would also help
if I had images for 2 different printouts from the same printer.  It could be
that the 2600N printer does not timestamp, but only logs the serial number.

Hope this helps!  I'll keep looking into it, and I'll let you know what I find.
 Feel free to contact me with any questions.

Best regards,
Patrick




	
		
______________________________________________________
Click here to donate to the Hurricane Katrina relief effort.
http://store.yahoo.com/redcross-donate3/