"The problem stems from a combination of compression level and resolution setting," Xerox said in a statement on Tuesday. "The devices mentioned are shipped from the factory with a compression level and resolution that produces scanned files which are optimized for viewing or printing while maintaining a reasonable file size. 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."
"For data integrity purposes, we recommend the use of the factory defaults with a quality level set to 'higher,'" the company advised.
Xerox said the machines had warned users for years that character substitution could occur at lower quality and higher compression settings.
A message on a web interface to the copier warns: "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."
Martyn Williams covers mobile telecoms, Silicon Valley and general technology breaking news for The IDG News Service. Follow Martyn on Twitter at @martyn_williams. Martyn's e-mail address is email@example.com