Xerox Scan Issue
August 2013
Overview & Solution
Scan Issue Description
•
There have been concerns about Xerox® office devices creating errors while scanning.
We have confirmed that errors can occur under a set of limited conditions.
•
The errors stem from a specific software approach in some of our multifunction printers
(MFPs) when scanning stress documents to PDF format.
•
Xerox also confirms that this error does not occur when using everyday office documents
for printing, copying, traditional fax, or when scanning to non-PDF formats such as TIFF,
JPEG, and XPS. The error is very unlikely to occur with factory default settings on the
MFP.
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Overview of Scan Issue
•
14 office product families impacted by the scan issue; Only affects Scanning in PDF
format; does not impact printing, copying and traditional fax functions.
•
Designed for JBIG2 compression methods for customers who have specific workflows
that need very small file sizes. The “Quality / File size” setting that enabled this most
aggressive compression mode was labeled “Normal” and documented as having
potential for character substitution.
•
MFPs with factory default mode are set with the compression level & resolution
settings that produce reasonable file sizes and scanned files appropriate for viewing or
printing. It is unlikely that the issue of character substitution can occur when using
everyday office documents.
•
Current scan Issue is caused by a software bug in scanning function for factory default
mode due to which character substitution caused by pattern matching may occur with
stress documents (e.g. small fonts, low resolution, stray pixels, hard to read)
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List of Impacted Products
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Why Does the Error Occur - Pattern Matching
•
For text files, Xerox uses the JBIG2 industry standard for compressing documents (for
photographs, we use the more familiar JPEG standard).
•
The JBIG2 compression standard offers an option called “pattern matching.” The basic
premise of pattern matching is to search for repeating patterns.
•
When a pattern or character is recognized, instead of storing all of the pixels
associated with each individual pattern or character, the pattern is stored in a character
dictionary once, and referenced.
•
The “Normal Quality” mode uses the more aggressive JBIG2 compression and pattern
matching, producing the smallest files, and having the greatest likelihood of character
substitution.
•
The other modes utilize a much more precise version of pattern matching and Xerox
testing has shown everyday documents to be error -free.
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Pattern Matching Explained
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Character Substitution Explained
•
In order for the most aggressive compression to generate the smallest file possible,
Xerox implemented “pattern matching” based compression.
•
The risk with this compression method is with stress documents, which are defined as
documents with characters that have a very small font size, utilize low resolution
scanning/printing, may have been scanned as a photo, have stray pixels and in general
are difficult to read. With stress documents in high compression modes there is a
possibility of character substitution due to pattern matching as shown below.
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The Scan Patch Solution: Eliminate Pattern
Matching
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Patch turns off “pattern matching” which eliminates the problem entirely.

The “LL Patch” automatically disables pattern matching without any other changes to the existing
software version and makes it impossible to select pattern matching, even for device systems
administrators.

Xerox has created an audit capability to verify this patch has been installed. The specific identifier
”LL” has been added to the Network Controller software version for devices which are patched.
•
There is no other impact to the device software.
•
Text file sizes will increase but are competitive versus industry averages.
•
Little impact to photo and mixed documents
•
Scan Patch available for download at www.xerox.com/scanpatch
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Scan Patch Impact to File Size
•
Text file sizes will increase but are still competitive versus industry averages.
•
Little impact to photo and mixed documents
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Helpful Resources
• Patch available for download at
www.xerox.com/scanpatch
• Other resources on
www.xerox.com/scanpatch:

Scanning Q&A Document

How to Set Your Device Default
Settings

Scanning and Compressions
Whitepaper

LL Patch Expectations Brief

Xerox Blog on Scanning
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Conclusion
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Everyday Office Document and Stress
Documents
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Basics of Compression
•
Large files such as photographs can be compressed to make sharing/storing documents easier. An
8.5” x 11” scan of a photograph may be 35 MB, whereas a compressed version may be 1 MB to 5
MB depending on the compression option.
•
The quality of compressed images also varies. If the photograph is not compressed, the file size will
be large and of the highest quality possible based on the resolution and quality of the captured
image.
•
Compressing the file will produce varying degrees of quality and file size depending on the
compression choice.
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