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Storage - Memory All devices that are used to store image data.

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  #1  
Old November 30th, 2008, 10:30 AM
Michael Fontana Michael Fontana is offline
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Default Image-corruption

The other day, opening a tiff, I had closed a while ago, it had a colorfull line through the entire image:




No, it's not a corrupt RAWfile, as I could get the good copy from the backup.

The corruption happend after finishing all edits; therefore it must be due to a hardddisc-failure?

Edit: It's the only corrupted one, I found - any suggestions?
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  #2  
Old November 30th, 2008, 10:47 AM
Bart_van_der_Wolf Bart_van_der_Wolf is offline
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Quote:
Originally Posted by Michael Fontana View Post
The corruption happend after finishing all edits; therefore it must be due to a hardddisc-failure?

Edit: It's the only corrupted one, I found - any suggestions?
Hi Micheal,

It's more likely a data error during the writing of the file to disk. Something damaged the bit structure before, or while, it was being written to disk. It could be something as simple as an offset being changed, and whole lines of data make no sense anymore. How many lines were involved (a multiple of 8 or a multiple of 3 or 4?). Full width (horizontal) lines?

Hard disks relocate blocks of data as they generates crc errors, so they are not likely to create isolated errors, and if they do then they are not likely to exactly span a line of image width.

Bart
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Old November 30th, 2008, 11:02 AM
Michael Fontana Michael Fontana is offline
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Good evening, Bart

it has 12 horizontal lines in height and goes through the entire image, which is in portrait orientation. Interestingly enough, all the exifs are available.

I'd be more than glad to follow your explication, but the corrupted file has exactly the same creating and change-time, as the not corrupted backup-version.
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Old November 30th, 2008, 12:45 PM
Bart_van_der_Wolf Bart_van_der_Wolf is offline
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Quote:
Originally Posted by Michael Fontana View Post
Good evening, Bart

it has 12 horizontal lines in height and goes through the entire image, which is in portrait orientation. Interestingly enough, all the exifs are available.

I'd be more than glad to follow your explication, but the corrupted file has exactly the same creating and change-time, as the not corrupted backup-version.
Hi Michael,

Whatever the exact moment of corruption, it looks like a TIFF (?) file header corruption.
The TIFF data is written in one of a number of possible layouts as rows of data, with tags/offsets in a header that signify where the data begins and how long a line is .
All it takes is to corrupt a few of those offsets, and the entire corresponding lines are potentially turned to garbage.

The question where it originated remains. Was the copy a copy of the other file, or were both written to different locations from the application. Which file has the more recent date/time?

Bart
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Old November 30th, 2008, 01:42 PM
Michael Fontana Michael Fontana is offline
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Quote:
Originally Posted by Bart_van_der_Wolf View Post

The question where it originated remains. Was the copy a copy of the other file, or were both written to different locations from the application. Which file has the more recent date/time? Bart
Bart, that's the point I' ve difficulties to understand:

The corrupted one must have be fine, at time x, when copied into the backup, as its been the master:

the intact, aka backup-copy is a "clone" from the corrupt one.
As both have identical °creating time° und °changed time° something must have happend outside the image editing/saving.

If the corrupt one would have edited and saved again, it would necessairly show a different °changed time°

Therefore, my initial thought was a hardisc failure.
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Old November 30th, 2008, 01:48 PM
Nicolas Claris Nicolas Claris is offline
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Bonsoir Michael
didi you move the corrupted file from a disc to another?
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Old November 30th, 2008, 02:46 PM
Michael Fontana Michael Fontana is offline
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Bonsoir Michael
didi you move the corrupted file from a disc to another?
Bonsoir Nicolas

nope, its been on the internal drive - a miror-RAID - since its birth.
Nope again for forced shutdowns, etc...

As I could replace it with the backup, its not a big deal, but I' d like to know a bit more, for the other files.
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Old November 30th, 2008, 10:49 PM
Nicolas Claris Nicolas Claris is offline
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Quote:
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but I' d like to know a bit more, for the other files.
I can understand that!

(Have you run any utility to defrag your HD ?)
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Old December 1st, 2008, 03:35 AM
Michael Fontana Michael Fontana is offline
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I can understand that!

(Have you run any utility to defrag your HD ?)
Bonjour Nicolas

I don't think defragmentation is the naughty guy, here. Anyway on OS-X, after 10.3.9, defragmentation is done automatically.

Yes, I °clean° the harddisc regularly with diskwarrior.
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Old December 1st, 2008, 04:42 AM
Nicolas Claris Nicolas Claris is offline
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Quote:
Originally Posted by Michael Fontana View Post
Bonjour Nicolas

I don't think defragmentation is the naughty guy, here. Anyway on OS-X, after 10.3.9, defragmentation is done automatically.

Yes, I °clean° the harddisc regularly with diskwarrior.
Well, defragmentation maybe the culprit and would explain why the duplicate has the same date and don't show the problem...

Defragmentation process moves part of splited files to concanate them into one single file, at this precise moment, a failure in -for example- power (micro-cut) may cause the corruption… imho…

And on my own, I avoid for a long time now utilities such as "diskwarrior"… imho again
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Old December 1st, 2008, 11:31 AM
Michael Fontana Michael Fontana is offline
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Bonsoir Nicolas

thanks, now I understand your defrag-explication.
Then there would be a 1/1000'000 chance to get it again, hopefully ..

As for DW:
I agree much with you on these tools, but DW is different, as it doesn't patches things. It doesn't touches the files, but only replaces the directory of a hd. I use it - as the only tool - quite for a few years now, and nothing bad happend before.

"DiskWarrior will rebuild your disk directory, eliminating all existing directory damage. The directory DiskWarrior creates is also optimized for maximum directory performance, and this will speed up the performance of your disk." from DW-site
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Old December 1st, 2008, 12:01 PM
Nicolas Claris Nicolas Claris is offline
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Quote:
Originally Posted by Michael Fontana View Post
"DiskWarrior will rebuild your disk directory, eliminating all existing directory damage. The directory DiskWarrior creates is also optimized for maximum directory performance, and this will speed up the performance of your disk." from DW-site
hmmm
that's a quote from the vendor…
I do prefer to repair disk/permission, clone the HD to another, then format the 1st one and clone back…
Takes a bit more time, but safe! I do that 'bout once a year.

And I have a special raid 200 Gb disks for CS scratch… (doing less defrag on boot disk)

Now, for video wich needs real disk speed, we use raids, regularly backed-up and formatted…
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