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Lossy data and incorrect data


Lossy data and incorrect data

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Phil Factor
Phil Factor
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Comments posted to this topic are about the item Lossy data and incorrect data


Best wishes,

Phil Factor
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wolfkillj
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This highlights one of the downsides of the digital revolution. Digital capture and reproduction of the physical phenomena of sounds and images always lose some data. With CDs, the sampling rate is high enough that most listeners never notice that the waveform data from points in between samples is missing, but the groove on a vinyl record is still a more complete representation of the waveform that existed at the time of recording. Same with copy machines - a machine that scans, digitizes, and then prints the image loses some data, but the resolution is usually high enough that most people don't notice a difference, while a photostatic or electrophotographic copy machine produces an image that is much more true to the original.

The conveniences of digital processes make them preferable to the analog processes of the past. The technology has advanced to the degree that digital capture and reproduction processes are adequate for any purpose except those that require the utmost fidelity to the original. Xerox's press release confirms that the problems noted in the article Phil linked are related to bugs in the software that compresses the captured images rather than any inherent limitation of digital capture and reproduction.

Somewhat OT, I'm old enough to remember using a high-speed Kodak electrophotographic copier with a fancy finishing unit attached. The whole thing was about 20 feet long, and, like all electrophotographic copiers, it had to capture the image of the original for every copy made, so it had a mechanism that ran the original over and over the platen - it worked so fast that the flash lamp seemed almost like a strobe light.

Jason Wolfkill
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Tobar
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Oh to be a lawyer working on this case. You will most likely be assured a job for life. It will take years just to get everyone to understand the problem. [ I was going to put a smiliey in here, but the consequences of the possible alteration to "financial records or medical doses" takes some of the humor shine off for me. ]

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lshanahan
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wolfkillj (8/14/2013)
Somewhat OT, I'm old enough to remember using a high-speed Kodak electrophotographic copier with a fancy finishing unit attached. The whole thing was about 20 feet long, and, like all electrophotographic copiers, it had to capture the image of the original for every copy made, so it had a mechanism that ran the original over and over the platen - it worked so fast that the flash lamp seemed almost like a strobe light.


Ok, do I really have to mention ditto machines? :-D Youngsters...

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Just my $0.02 from over here in the cheap seats of the peanut gallery - please adjust for inflation and/or your local currency.
Tobar
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And don't forget Mimeograph!! Which I learned is much older technology. Ah, the Ditto aroma, a strong memory still. http://www.chattanoogan.com/2006/7/27/89955/Remembering-the-Ditto-and-Mimeograph.aspx

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wolfkillj
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lshanahan (8/14/2013)
wolfkillj (8/14/2013)
Somewhat OT, I'm old enough to remember using a high-speed Kodak electrophotographic copier with a fancy finishing unit attached. The whole thing was about 20 feet long, and, like all electrophotographic copiers, it had to capture the image of the original for every copy made, so it had a mechanism that ran the original over and over the platen - it worked so fast that the flash lamp seemed almost like a strobe light.


Ok, do I really have to mention ditto machines? :-D Youngsters...


Well, I'm old enough to have seen and extensively used copies made on mimeograph and ditto machines, but never really used the machines themselves. I remember how it could be so much harder to read the last copy to come off the ditto machine than the first due to the depletion of ink supply on the "ditto master". And who can forget that ditto machine smell?

Jason Wolfkill
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Tobar
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wolfkillj (8/14/2013)
Well, I'm old enough to have seen and extensively used copies made on mimeograph and ditto machines, but never really used the machines themselves.

Old enough to have used the machines my first year of teaching.

I remember how it could be so much harder to read the last copy to come off the ditto machine than the first due to the depletion of ink supply on the "ditto master".

Happy, after the fact, that my last name is early in the alphabet. At least when we were seated in name ascending rank arrangement. :-P

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chrisn-585491
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Database people have a natural suspicion of the quality of data until they’ve proven to their satisfaction that it is OK.


I have a motto:

"All data is bad. Some data is just worse than other data..."

Make no assumptions about any data at any time. Always validate and test!
Tobar
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chrisn-585491 (8/15/2013)
"All data is bad. Some data is just worse than other data..."

True, true.

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marlon.seton
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Tobar (8/14/2013)
wolfkillj (8/14/2013)
Well, I'm old enough to have seen and extensively used copies made on mimeograph and ditto machines, but never really used the machines themselves.

Old enough to have used the machines my first year of teaching.


Used the Banda / Gestetner (what we call the Ditto in the UK) machine my year of teacher training ('79-'80) and first couple of years of teaching. Photocopying would have cost about 30 - 50p (45 - 75c) a sheet. By the time I quit teaching in '86, schools had photocopiers in general use.

I remember how it could be so much harder to read the last copy to come off the ditto machine than the first due to the depletion of ink supply on the "ditto master".

Happy, after the fact, that my last name is early in the alphabet. At least when we were seated in name ascending rank arrangement. :-P


You had to sit in name ascending rank arrangement? I cannot imagine something so militaristic.
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