Reminded me of this: "Digital Photocopiers Loaded With Secrets" http://www.youtube.com/watch?v=Wa0akU8bsOQ
Don't all these kinds of machines have a scrub disk option? Or just take the disk out and scrub it.
Xerox scanners and photocopiers randomly alter numbers in scanned documents
111–118 of 118 posts
Re: Xerox scanners and photocopiers randomly alter numbers in scanned documents
#112Earlier quoted context omitted.
The trouble is, there is no reasonable in doubt anymore. Copying and digital archiving both rely on the premise that there is no manipulation. Lossy compression always seemed to be OK because the image quality was reduced without changing the integrity and structure of the image. This will essentially destroy credibility of digital records. Every shyster and hack lawyer will pull this as defense in court. Also it's n…
> Every shyster and hack lawyer will pull this as defense in court. I don't think it will be so trivial to use this defense. As somebody claimed, JBIG2 _reuses_ sufficiently similar blocks, so I guess it can be relatively easily determined whether the document has been messed up by lossy compression.
Assuming the document has not since been converted by anything that might have re-compressed the images.
Re: Xerox scanners and photocopiers randomly alter numbers in scanned documents
#113I don't think it's necessarily an issue of inexcusable incompetence: it seems like one of those faults which is obvious in retrospect but very difficult to predict. Why shouldn't Xerox use a standard compression algorithm in their scanner/copiers? That would seem to be a safer choice than writing a lossy compression algorithm from scratch. QA testing probably was on the order of 'picture looks right'; after all, why…
> Why shouldn't Xerox use a standard compression algorithm in their scanner/copiers? I have never heard of JBIG2. I implemented JPEG2000 codecs from scratch, arithmetic coding compression and I have never heard of JBIG2. And here the are using and it others claiming it is just a standard run of the mill thing. > That would seem to be a safer choice than writing a lossy compression algorithm from scratch. Going out on…
> Sorry. This is the company whose name is the equivalent to the verb "to copy". If plugging in an obscure codec from some place and checking if one picture looks "OK" is their idea of QA then they deserve all the ridicule and lawsuits stemming from this.
You need to put your corporate drone hat on. How many people are involved in making a Xerox copier? How many parts are reused from the previous model? How much software is reused?
My best guess is that a large number of components in a copier are engineered in isolation. The image compression people responsible for implementing JBIG2 probably don't even care about correctness beyond some threshold ("not my problem"). The people responsible for ensuring correct copying may not even know that an image compression exists, and even if they do, may not understand the technical nuances of JBIG2, and also may not even have the right documents to find an instance of such a problem.
Re: Xerox scanners and photocopiers randomly alter numbers in scanned documents
#114Earlier quoted context omitted.
Could you share with us a list of other scanners that have this problem, so we can avoid them?
I tried various compression and density settings on my Fujitsu scanner, and didn't see any problems like those mentioned in the article.
Thanks. I scan a ton of documents with my Fujitsu scanner, so that's particularly relevant to me.
Re: Xerox scanners and photocopiers randomly alter numbers in scanned documents
#115This was predictable. JBIG2 is in no way secure for document processing, archiving or whatsoever. The image is sliced into small areas and a probabilistic matcher finds other areas that are similar. This way similar areas only have to be stored once. Yeah right, you get it, don't you? They are similar, not equal. Whenever there's a probability less than 1, there's a complementary event with a probability larger than…
"The image is sliced into small areas and a probabilistic matcher finds other areas that are similar."
"Whenever there's a probability less than 1, there's a complementary event with a probability larger than 0."
If that alone is reason for why JBIG2 is in no way secure for document processing, archiving or whatsoever - then I've got some bad news for you. Because if that's the case you really shouldn't be using a computer for, well, anything.
Re: Xerox scanners and photocopiers randomly alter numbers in scanned documents
#116Reminded me of this: "Digital Photocopiers Loaded With Secrets" http://www.youtube.com/watch?v=Wa0akU8bsOQ
Don't all these kinds of machines have a scrub disk option? Or just take the disk out and scrub it.
Possibly. The focus of the story was that (at least at the time) many of the owners/leasers of these machines had no idea they contained drives that retained the scanned documents.
Re: Xerox scanners and photocopiers randomly alter numbers in scanned documents
#117Earlier quoted context omitted.
I think we can all agree that e-mails should have finite size - it's not a very good protocol for transferring multi-gigabyte files, for sure! Where we would disagree is where that limit should be drawn. I've seen systems in this day and age that fail in the face of e-mails as small as 5 megabytes (e.g. Yahoo Popgate) which IMHO is far too low - but evidently some sysadmins disagree with me!
Email size is a technical issue that shouldn't be limiting (or even visible) to the end user. If an end user wants to send a multigigabyte file to another user's email address - why not? The email client could launch a background upload process and email a link to get that file by, say, bittorrent... Some protocol extensions and software support would be needed, but that can be done and, as users need it, probabpy sh…
Oh, the protocols are already in place; consider RFC2017.
Sending a link to something (even wrapped in a nice ui and container) has pretty different semantics from actually sending the something, though.
Re: Xerox scanners and photocopiers randomly alter numbers in scanned documents
#118Earlier quoted context omitted.
Then realize you shouldn't define your life based on some digital records.
I don't define my life based on some digital records. But law enforcement (or the executive branch of the US Federal Government, including the NSA) does. And therein lies the problem. Someone will be convicted (perhaps even without the intervention of a court) based on unimpeachable but falsified digital records.
The fact that this conversation is taking place makes it unlikely for those records to be regarded as "unimpeachable".