Home > Computing > Changing numbers: Computer scientist discovers…

Changing numbers: Computer scientist discovers alarming issue with Xerox scanners

[Please note: An update has been added at the end of this article.]

If you scan a document, the assumption is that, y’know, an exact copy will be produced. It won’t be different, because it’s a scanner. It scans.

Well, it seems it may be time to dump that assumption, as a German computer scientist by the name of David Kriesel has recently discovered that several Xerox scanner/copier machines has been changing numbers on documents he’s been scanning.

Kriesel found, for example, that a ‘6’ would sometimes be scanned as an ‘8’, and vice versa. On one occasion, figures in a construction plan were messed up. “One room in the construction plan was – as the copy told us – about 22 square meters large, whereas the next room, a lot larger, was assigned a label with 14 square meters,” Kriesel said.

xerox before after

Other users of Xerox scanners have reportedly managed to replicate the issue, leaving us to wonder just how many documents are floating about out there with the wrong information on them – invoices, sales figures, budgets, property records, medical information, business forecasts….

The problem has been linked to JBIG2 compression software loaded onto a number of Xerox machines. From his own research, Kriesel has found that the Xerox WorkCentre models 7535 and 7556 are affected, though since highlighting the issue he’s received information about other affected machines, all of which are listed on his website.

The software in question creates smaller file sizes when the normal setting is selected. However, it appears that in this setting – in some instances – the software is substituting figures it considers the same.

The issue is potentially a serious one, as Kriesel pointed out in a post on his blog:

Anyone using those WorkCentres has to ask himself:

– How many incorrect documents (even though they look correct!) did I produce during the last years by scanning with Xerox machines? Did I even give them to others?

– What dangers are imposed by such possible document errors? Is there a danger of life for someone?

– Can I be sued for such errors?

Xerox response

The computer scientist contacted Xerox about the issue, and the company responded in a post on its blog on Tuesday.

“We do not normally see a character substitution issue with the factory default settings, however, the defect may be seen at lower quality and resolution settings,” said principal engineer Francis Tse. “For data integrity purposes, we recommend the use of the factory defaults with a quality level set to ‘higher.’”

Tse adds that when a user selects the lower quality/higher compression option – which causes the JBIG2 software to kick in – a message shows up warning that “text quality degradation and character substitution errors may occur with some originals.”

Having heard the explanation, it still seems bizarre that a scanner – or scanners – can be rolled out with software that makes errors, even if a warning does show up beforehand. With the majority of documents sent through a machine like this likely to be of some importance, no one wants to end up with potentially troublesome inaccuracies, or waste time checking through all the figures. As Xerox says, best to keep it on the higher quality setting.

UPDATE: Xerox vice president Rick Dastin said Wednesday the company is now creating a software patch to deal with the issue. “Xerox is developing a software patch that can be remotely downloaded to each device,” Dastin said on the company’s website. “The software patch will disable the highest compression mode thus completely eliminating the possibility for character substitution. Xerox will begin rolling out the patch within a few weeks.”

In addition, he said Xerox will provide a guide for users showing how to check the current device scan settings and how to return them to the factory default setting, which will also prevent any errors occurring.

“We apologize for any confusion and inconvenience this has caused our customers,” Dastin said. “We are working tirelessly to address these issues — working closely with our partners and customer service teams across the globe to both proactively inform customers as well as help them solve the issue.”

[via BBC] [Image: Timy / Shutterstock]