Feeds

Xerox copier flaw changes numbers in scanned docs

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

Choosing a cloud hosting partner with confidence

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".

Beginner's guide to SSL certificates

More from The Register

next story
Ex-US Navy fighter pilot MIT prof: Drones beat humans - I should know
'Missy' Cummings on UAVs, smartcars and dying from boredom
Xperia Z3: Crikey, Sony – ANOTHER flagship phondleslab?
The Fourth Amendment... and it IS better
Don't wait for that big iPad, order a NEXUS 9 instead, industry little bird says
Google said to debut next big slab, Android L ahead of Apple event
Microsoft to enter the STRUGGLE of the HUMAN WRIST
It's not just a thumb war, it's total digit war
Netscape Navigator - the browser that started it all - turns 20
It was 20 years ago today, Marc Andreeesen taught the band to play
A drone of one's own: Reg buyers' guide for UAV fanciers
Hardware: Check. Software: Huh? Licence: Licence...?
The Apple launch AS IT HAPPENED: Totally SERIOUS coverage, not for haters
Fandroids, Windows Phone fringe-oids – you wouldn't understand
Apple SILENCES Bose, YANKS headphones from stores
The, er, Beats go on after noise-cancelling spat
prev story

Whitepapers

Forging a new future with identity relationship management
Learn about ForgeRock's next generation IRM platform and how it is designed to empower CEOS's and enterprises to engage with consumers.
Cloud and hybrid-cloud data protection for VMware
Learn how quick and easy it is to configure backups and perform restores for VMware environments.
Three 1TB solid state scorchers up for grabs
Big SSDs can be expensive but think big and think free because you could be the lucky winner of one of three 1TB Samsung SSD 840 EVO drives that we’re giving away worth over £300 apiece.
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.