Feeds

Xerox copier flaw changes numbers in scanned docs

WorkCentre 7535 and 7556: 'Character substitution errors may occur'

Security for virtualized datacentres

Updated A German PhD student has found a flaw in some Xerox Workcentres that fudges the numbers on some scans thanks to poor data compression.

Last Wednesday, computer science student David Kriesel was scanning in some building plans on a Xerox WorkCentre, and when checking the copies he found some of the dimensions of the plans had been altered, with three room measurements out of sync with the original documents. In particular, the number six was being changed to an eight.

The problem appears to affect documents scanned as PDFs without any character recognition (OCR) enabled, and Kriesel found that he could replicate the dodgy digits. He notes the flaw was most potent at 200 DPI copies using a seven or eight-point Arial typeface.

Kriesel found the flaw was present on the WorkCentre 7535 and 7556 models and posted a blog piece about his research. Judging from the wave of interest it generated, the problem is more widespread than he knew, with the flaw reportedly reproduced on six WorkCentre models and two of Xerox's ColorQube range.

False copied numbers from Xerox

Maybe last year's annual results weren't so good.

As for the cause, Kriesel originally thought there must be something wrong with the copier's data-compression algorithm, which was recognizing low-resolution numbers improperly. Emails he received after publishing suggest it's a problem with the JBIG2 compression system those copiers use.

"This algorithm creates a dictionary of image patches it finds 'similar'," he said. "Those patches then get reused instead of the original image data, as long as the error generated by them is not 'too high'. Makes sense."

According to a statement released by Xerox, he's right. The company confirmed that the problem is caused by a combination of compression levels and resolution setting with the JBIG2 system, saying it has "inherent tradeoffs under low resolution and quality settings."

However, Xerox says that the problem is essentially due to the settings users have put into individual copiers. Xerox recommends using the factory default option of higher image quality when setting up the copier, and points out that if the lower quality option is picked, the following disclaimer is displayed:

"The normal quality option produces small file sizes by using advanced compression techniques. Image quality is generally acceptable, however, text quality degradation and character substitution errors may occur with some originals."

Legally, then, Xerox is in the clear, but that's going to be cold comfort if your newly built house extension collapses in the middle of the night. ®

Update

Xerox has been in touch to say that a software patch has been issued for the scanning problem and reiterated that the flaw doesn't affect "standard printing, copying and traditional fax functions".

New hybrid storage solutions

More from The Register

next story
Apple iPhone 6: Missing sapphire glass screen FAIL explained
They just cannae do it in time, says analyst
Slap my Imp up: Bullfrog's Dungeon Keeper
Monsters need to earn a living too
Oh noes, fanbois! iPhone 6 Plus shipments 'DELAYED' in the UK
Is EMBIGGENED Apple mobile REALLY that popular?
Apple's big bang: iPhone 6, ANOTHER iPhone 6 Plus and WATCH OUT
Let's >sigh< see what Cupertino has been up to for the past year
The Apple Watch and CROTCH RUBBING. How are they related?
Plus: 'NostrilTime' wristjob vid action
Apple's SNEAKY plan: COPY ANDROID. Hello iPhone 6, Watch
Sizes, prices and all – but not for the wrist-o-puter
Apple Pay is a tidy payday for Apple with 0.15% cut, sources say
Cupertino slurps 15 cents from every $100 purchase
prev story

Whitepapers

Providing a secure and efficient Helpdesk
A single remote control platform for user support is be key to providing an efficient helpdesk. Retain full control over the way in which screen and keystroke data is transmitted.
Top 5 reasons to deploy VMware with Tegile
Data demand and the rise of virtualization is challenging IT teams to deliver storage performance, scalability and capacity that can keep up, while maximizing efficiency.
Reg Reader Research: SaaS based Email and Office Productivity Tools
Read this Reg reader report which provides advice and guidance for SMBs towards the use of SaaS based email and Office productivity tools.
Security for virtualized datacentres
Legacy security solutions are inefficient due to the architectural differences between physical and virtual environments.
Secure remote control for conventional and virtual desktops
Balancing user privacy and privileged access, in accordance with compliance frameworks and legislation. Evaluating any potential remote control choice.