Xerox responds to the recent character substitution issue

http://realbusinessatxerox.blogs.xerox.com/2013/08/06/always-listening-to-our-customers-clarification-on-scanning-issue/

by soulclap • 13 years ago

61 67 13 years ago

realbusinessatxerox.blogs.xerox.com

soulclap• 13 years ago

Previous discussion: https://news.ycombinator.com/item?id=6156238

Follow-up blog post about a conference call with Xerox: http://www.dkriesel.com/en/blog/2013/0806_conference_call_wi...

jevinskie• 13 years ago

Inadvertent downvote, I'm sorry! =(

dsr_• 13 years ago

Countered.

quantumpotato_2• 13 years ago

(OT: how do you downvote on HN?)

wtallis2• 13 years ago

So they claim that the fine print warns about character substitution. But they still are willing to label the option with that problem "normal quality" and suggest using "high quality" to get strictly image compression applied with no OCR. They don't seem to understand that a photocopier should in its normal operating mode never do post-processing that creates such surprising and misleading artifacts - better illegible and obviously so than legible but incorrect.

Don't get me wrong - using OCR is a great compression technique, but if it isn't reliable enough, it shouldn't be the default or "normal" setting.

hyborg787• 13 years ago

This has nothing to do with OCR. It's an issue with the JBIG2 compression re-using similar patches as substitutes for certain areas of the images if they're "close enough". This issue is exacerbated at lower resolutions.

ToothlessJake5• 13 years ago

Thats OCR...

wtallis2• 13 years ago

The process that's in use and what you consider to be true OCR are very similar, differing mainly in the last step (where OCR maps to a standard character set, but JBIG2 creates one on the fly along with a corresponding font). However, the errors at issue arise from part of the process where JBIG2 and OCR are doing pretty much the same thing, so even if the analogy is flawed, it is still highly instructive. Saying this has nothing to do with OCR is quite simply wrong, since this is clearly very closely related with OCR even if it doesn't meet your exact (unspecified) definition of OCR.

klodolph• 13 years ago

There's no OCR involved here. None.

All it's doing is recognizing "similar" patches of the image and coalescing them, which is what it's supposed to do, according to the standard. Yes, it's too aggressive.

Dylan168074• 13 years ago

The stated goal of JBIG2 is to recognize 'characters' on the fly and compress them together. It's not traditional OCR but I wouldn't take such a hard line.

dandelany• 13 years ago

Whether or not we're calling it OCR has zero bearing on the point of this comment. I can't believe this entire thread is hackers bikeshedding about whether it's OCR or not - it's like the definition of pedantism.

xahrepap• 13 years ago

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.

I might have read it wrong, but from how I understood it the default settings don't have this problem. It's when people adjust the quality settings to be lower. Am I wrong?

gpvos3• 13 years ago

You are correct. The default setting is "high" or "higher"; I don't know which. The setting that may copy blocks of characters around is the lowest setting and is called "normal", and comes with some small print on the screen that actually warns you for the character substitution.

eksith3• 13 years ago

"We do not normally see a character substitution issue with the factory default settings..."

It shouldn't be seen with any setting. Nothing you can do to the device (short of involving a hammer) should change the content in any way. Compress, resize, zoom, do whatever, but it simply must not change the content at any time at any resolution/quality.

I'm just flabbergasted that such a compression scheme was ever implemented in the first place. Surely, there are alternative OCR based methods do compression that don't introduce these artifacts (that's putting it mildly) at lower resolutions.

dman• 13 years ago

So you only want non lossy compression as an option?

eksith3• 13 years ago

By "lossy" you mean "17" may look like a crappier "17" with reasonable confidence, but will never, ever, become "21" at any compression setting, then I don't mind lossy. That's not asking for too much, is it?

ddunkin2• 13 years ago

By default, sure, for people who don't know about these settings, they are setting themselves up for failure when a few numbers get transposed. They should ship the device with highest quality settings so your customers are impressed out of the box, instead of being disappointed that they have to tune the device to get a high quality copy. If you must save a few bytes in this age, then you can turn on these crazy settings as you like.

I can just see a legal loophole now for anyone using these devices, for example "the electronic document was modified by a Xerox and we don't have the original, those numbers were not what we signed, contract void".

No matter the case of an optional setting or the size of the font involved, this can have major consequences for people who trust the device to be an accurate representation in all cases, of what they put into it.

rwallace• 13 years ago

Of course! Lossy compression is tolerable for cat videos on YouTube where it doesn't matter if a few details are wrong. It is absolutely not tolerable for storage of important documents. This is something that should go without saying.

Looks like the company is trying to weasel out of it and there are going to have to be lawsuits. Though I didn't really expect otherwise; if the dice come up badly, the damage from this could exceed the net value of the company.

eyeareque• 13 years ago

Sounds like the "recognized industry standard JBIG2 compressor" is just about useless for copy machines. Why even give a user the ability to do this?

The only acceptable fix for this is to disable the ability to use lower compression qualities that have could EVER cause this to happen.

gpvos3• 13 years ago

JBIG2 is not the problem. It is perfectly possible to do lossless compression with JBIG2. They just set its options to do some overly aggressive compression.

ToothlessJake5• 13 years ago

I would wager JBIG2 is the problem when Xerox couldn't implement it properly.

"Normal" is an overly aggressive compression setting? Is that an overly aggressive setting for the end-user or for Xerox to be implementing in their hardware marketed to law firms?

mark-r• 13 years ago

These are multi function devices meant to be used by many people. If someone in your office has need to make occasional scans that need to fit in an email, isn't it natural to assume they might configure the machine for maximum compression? Why should that setting affect copies?

speeder• 13 years ago

I am quite disappointed by their response.

I expected something better from Xerox, instead it is a sort of: "You are a stupid costumer, leave it on default and stop bothering me, it is not my fault you find bugs when not using the default."

mikeash3• 13 years ago

Standard idiot-box weasel-wording. Another case study to put on the enormous pile of examples of how not to communicate with your customers.

Pretend you care, blame the users, and don't take any action. Hey, what could be wrong with that?

ARothfusz• 13 years ago

Is this a real response? It is bylined as "Guest Blogger" and is not in an official-looking blog.

Cyclosa• 13 years ago

Xerox is oh-so subtly shifting the blame on to the user. How slimy.

binarymax• 13 years ago

This is an absolutely hilarious technical response to a real world customer issue. The customer does not care one iota that their photocopier uses one compression algorithm over another. And the fact there is not one mention of the word 'copy' in that entire post, is very telling of the technical disconnect exhibited here. The 'Xerox devices' in question are completely broken from a usability perspective.

ddunkin2• 13 years ago

It's no longer a 'copy machine' at this point, it's an 'approximation machine' and can't even be trusted for legal purposes.

preinheimer• 13 years ago

Xerox: You had one job.

ChuckMcM• 13 years ago

That is an astonishing response. Reminds me a bit of the first time EMC pointed out that while it was possible to have your data corrupted in their hash based storage system, it probably would never happen.

I was expecting "Here is new firmware and we apologize for using JBIG2, won't happen again."

One wonders if JBIG2 is used in the storing of checks by banks (my bank these days only sends me images of my checks, never the actual check any more) or DMV records, or any number of things.

So in the previous thread I suggested a JBIG2 test image, now I want to build one that if you copy it, it goes from one thing to something else entirely!

nsxwolf• 13 years ago

When you read a scanned or copied document, your confidence in the information is based on its quality.

There comes a point when the quality is so poor that you no longer trust your interpretation. Is that a 3? An 8? If you can't tell, you will not act on that information without further clarification.

This compression algorithm destroys this process.

How can you trust what you are reading anymore? How do we know there isn't a bug that sometimes causes the content substitution when the source text is large and perfectly legible?

Disk space is not at enough of a premium to justify this.

205guy• 13 years ago

This is an interesting story with lots of odd comments.

First of foremost, I agree that Xerox putting their name on a product which creates an unfaithful copy is corporate suicide. Such an ancient paragon of computer innovation should be able to come up with a clever algorithm that compresses but doesn't substitute image bits.

But...

- The original story[1] didn't mention that the product itself warns against the very thing they are reporting. Did they ignore that warning, did the copier not show it, did they use a setting that did not have the warning? Their further posts cover the issue, so it looks like somebody else set the resolution and ignored the warning.

- Calling what the JBIG2 algorithm does "OCR" is misleading. OCR is pretty much understood to be analog text (image) to digital text (ASCII, UTF-32). Matching to a real character set and outputting those characters is a defining part of true OCR. It's also confusing because the copiers have a true OCR function, and this is not related. What JBIG2 does, I would call it "sub-image matching and substitution."

- Calling JBIG2 "lossy" is also misleading. I suppose it is lossy by definition, but lossy is usually limited to pixel effects as seen in JPG, no image blocks.

- JBIG2 seems like an algorithm that shouldn't be used on low-res text documents. You might say it's just a configuration of the algorithm, but if engineers can't take it as a tool and use it correctly, you start to wonder if it's a problem with the tool.

[1] http://www.dkriesel.com/en/blog/2013/0802_xerox-workcentres_...?

morsch• 13 years ago

I was curious to see how JBIG2 fares compared to JPEG, and found a benchmark from 2010 [1] comparing the file size of the resulting PDF:

  convert *.jpg JPEG.pdf -- 43777 kb
  convert *.png PNG.pdf -- 6907 kb
  jbig2 -b J -d -p -s *.jpg; pdf.py J > JBIG2.pdf -- 947 kb
  jbig2 -b J -d -p -s -2 *.jpg; pdf.py J > 2xJBIG2.pdf -- 1451 kb

Quite a difference. I don't quite understand how JPEG fares so poorly compared to (lossless) PNG, maybe because it doesn't do monochrome?

[1] http://ssdigit.nothingisreal.com/2010/03/pdfs-jpeg-vs-png-vs...

duskwuff• 13 years ago

JPEG is optimized for photographic images with lots of smooth gradients. It does badly with sharp edges, which scanned documents tend to contain a lot of.

emmelaich• 13 years ago

Off topic but it was awesome to see a link with "perl-bin" in it. I nice insight into what really does the important work in these big shiny corporations. :-)

workbench2• 13 years ago

"the device web user interface"

Why on earth does a scanner have a web interface

mathattack• 13 years ago

This may be an issue of giving people too much choice. Should users have the freedom to make terrible mistakes? Maybe in Linux, but not Windows. Similarly, you don't want an inexperienced secretary to get your company in legal trouble. Blaming the users can kill Xerox.

Xerox responds to the recent character substitution issue

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