• Please use real names.

    Greetings to all who have registered to OPF and those guests taking a look around. Please use real names. Registrations with fictitious names will not be processed. REAL NAMES ONLY will be processed

    Firstname Lastname

    Register

    We are a courteous and supportive community. No need to hide behind an alia. If you have a genuine need for privacy/secrecy then let me know!
  • Welcome to the new site. Here's a thread about the update where you can post your feedback, ask questions or spot those nasty bugs!

Image-corruption

Michael Fontana

pro member
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?
 
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
 

Michael Fontana

pro member
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.
 
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
 

Michael Fontana

pro member
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.
 

Michael Fontana

pro member
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.
 

Nicolas Claris

Administrator/Moderator
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
 

Michael Fontana

pro member
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
 

Nicolas Claris

Administrator/Moderator
"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…
 
Top