Solved Does cloning contribute to JPG image deterioration over time

February 15, 2015 at 15:48:10
Specs: Windows XP, P4 2.6GHZ/PC3200 1.5gig
Hi,
Every few months I make a backup (clone) of my OS to another hard drive. Does this practice cause deterioration of my images (jpg, rw2, etc) over time?
Thanks,
John

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#1
February 15, 2015 at 23:19:17
✔ Best Answer
No. Under normal circumstances the clone would be an exact copy. It's not the same as if you were to photocopy a picture and then photocopy the copy and so on.

The only time a problem might arise is if there's some hardware problem, maybe with the drive or bad ram or possibly a virus infection.


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#2
February 15, 2015 at 23:26:26
It will also occur if you open a JPG image, edit it, then re-save it. Every time you save a JPG more image data is lost owing to compression.

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#3
February 16, 2015 at 06:41:21
Hi DAVE/Phil,
Good, then I will continue my normal practice. The reason I wondered about it is for the exact reason Phil mentions, i.e. I thought that cloning may be similar to copying, in the sense that it is not an exact replica, and that over time my pictures would get worse and worse.
..... john

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Related Solutions

#4
February 16, 2015 at 11:18:59
Copying is indeed an exact replica so you should be fine.

However, donkeys years ago I had a silly habit of enclosing bmp files in a zip rather than changing them to jpg. Moving from computer caused picture deterioration. I don't really know why but suspect a later un-zipper used a different algorithm.

Always pop back and let us know the outcome - thanks


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#5
February 16, 2015 at 13:25:31
Hi Derek,
If you don't mind my asking, what were the symptoms of this 'picture deterioration'? What got me onto this whole cloning question is that some of my 'old pictures' appear to be 'over sharpened'. Now, when I started taking pictures I did tend to lean a little hard on the sharpening tool, so, what I'm seeing could be just that.
...... john

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#6
February 16, 2015 at 14:00:42
Over sharpening can be an issue but mine were heavily pixelated and blotchy. I doubt they have much bearing on your issue - just an aside really.

Always pop back and let us know the outcome - thanks


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#7
February 16, 2015 at 16:15:17
Right ...... thanks.
...... john

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#8
February 17, 2015 at 08:14:42
Perhaps I should have explained, taking a copy of a file is not like taking a photo of a picture where you get loss or deterioration, however small.

Copying a file on a computer all comes down to it being "digital", a bit for bit reconstruction. This means you can copy a copy, or a copy of a copy, as many times as you wish and the results will still remain exactly the same as the original unless (unusually) some sort of corruption creeps in.

Same applies to audio, an analog copy (recording) can only be done a few times before deterioration is noticeable. Not so a digital copy, for the same reasons as given above.

While I am generalising - a jpg picture file is compressed, unlike a bmp file which is therefore much larger. You have to be a purist to notice the difference though, unless you are magnifying a small area.

Always pop back and let us know the outcome - thanks


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#9
February 17, 2015 at 20:04:21
Hi Derek,
Thanks for the information. So, it's the compressing and decompressing that causes the loss of data, i.e. one can copy, and copy the copy, etc of a bitmap until hell freezes over and never have any derterioration?
.... john

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#10
February 18, 2015 at 07:29:46
Well, compressing and decompressing "should" be OK if using the same compress/decompress program. There is a standard "one off" loss of data due to the way compression works but mostly it is not noticeable and it should not vary from then on. However, something definitely went wrong with mine. Unfortunately I have no idea when it happened as I'd transferred these files from computer to computer before I spotted it.

Computers are capable of corrupting files if there is a glitch. It is something I've seen at odd times but over a number of years - certainly not a regular thing.

Always pop back and let us know the outcome - thanks


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