All three compression modes mangling numbers on Xerox WorkCentre 7545, reader reports also on 7655

As all of you probably know by now, the Xerox devices have three compression settings: Normal, higher and highest. Xerox claimed in their questions and answers sheet that the normal would be “the JBIG 2 setting” mangling numbers, and the rest would be safe at 200dpi resolution and above.

A few days ago, I found that on a Xerox WorkCentre 7545 in my hometown Bonn, besides the normal mode, also the “higher” compression mode was mangling numbers, even on a generous 300 dpi resolution. I reported my findings to Xerox, and after they tested it on one of their 7545s in the US, consequently seeing mangled numbers as well, I wrote a detailed blog post.

This already was in stark contrast to their on-screen notifications, their manuals (at least the ones I know) and even their current press statements, as all of these only issue character substitution warnings with respect to “normal” compression or even tell explicitly the user will be safe with the other compression modes.

What hasn't been done so far are tests on the one compression setting not in question yet. So today, I set out performing tests in “highest” mode, with 300 dpi, again on a WorkCentre 7545 (Software version 061.121.201.09700). Here is the result PDF as it was produced by the device. See for yourself. Unfortunately, again, numbers were mangled. As a result, at least on a WorkCentre 7545, one seemingly can't be sure to scan correct figures, regardless of the compression mode chosen out of normal, higher or highest.

I also verified that the user interface worked correctly, in particular that compression settings are actually applied. This is why I scanned across all compression settings again today. The file sizes seemed plausible: 21 KB, 34 KB and 67 KB for normal, higher and highest mode (all three files contained mangled numbers). I already forwarded the findings and the files to Xerox to see if they can replicate on their own devices again. However, this time I did not wait for their confirmation, but set myself a limit of three hours until publishing, as I personally think keeping back the information longer may be a bit dangerous.

Whats more, a reader emailed me a zip with some PDFs today, allegedly scans of a WorkCentre 7665. Likewise, all three compression modes seemed to have their numbers mangled. However, I did not attend the scanning process of these, so take this information as hearsay and as a warning.

Hope there will be a statement from Xerox soon.

Edit: I keep getting asked how many pages I have to scan to see false figures. Look at how many false figures there are – in all of my tests, one page worked out perfectly well. Just to be sure about it, of course, I often scanned some more pages.

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From a quick look at the scanned file (page 2) it is clear that even with this setting Xerox is still using JBIG2 compression:

pdfimages -list -f 2 -l 2 7545-highest.pdf 

page   num  type   width height color comp bpc  enc interp  object ID
---------------------------------------------------------------------
   2     0 image    1760  1248  gray    1   8  jpeg   no        13  0
   2     1 mask     2952  1822  -       1   1  jbig2  no        15  0
   2     2 mask      103    98  -       1   1  jbig2  no        16  0

(The line with the “jpeg” encoding isn't the image with the numbers, it's just the background of the page.)

1 | | 2013/08/11 22:47 | reply



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