In the simplest variation, this would be a fax machine that would examine a scan of an outgoing document and confirm that it had a reasonable amount of information content and provide a warn if it doesn't seem to (probably because the document was facing the wrong way when it was inserted). Depending upon price, a machine could use a number of ways to try to distinguish this.

-1- Include a page-density readout, to indicate whether a page was mostly white. It may be possible to include a VERY low resolution scan of the page (e.g. 0.5-5 dpi) in the fax log. I don't think any confidential information would be compromised by such a scan, but the user could confirm visually that the document that had been transmitted was at least somewhat reasonable. Even a cheap LCD could display a 0.5dpi scan, and even the cheapest graphical display could probably show 1-2dpi.

-2- Incorporate two light sources for scanning--one reflective and one transmissive. If far more content is visible in transmissive mode than reflective mode, that would suggest most of the page content is on the reverse.

-3- Even without special scanning hardware, it should be possible to distinguish ink bleed-through from deliberate content by examining the edge countours, and flag documents which appear to have nothing on them except the former.
-- supercat, May 14 2007

Many fax machines will print a summary of the fax sent, including a thumbnail of the first page. That helps after the fact, at least.
-- DrCurry, May 14 2007


People still use fax machines?
-- wagster, May 14 2007


I was once faxed a paint colour-chart by a decorator who expected me to make a choice from it while I was at work. The information content was low.
-- MaxwellBuchanan, May 14 2007


I thought this was a device that prevented one from accidently faxing a job application and resume to one's own boss.
-- nuclear hobo, May 15 2007



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