Spontaneous Photo Degradation

[rer]

Hi ! My name is Edi and I'm having an annoying problem : I have a Panasonic DMC FZ 7 camera ( yes, I know it's a Cannon users forum , but I'm kind a desperate ) and a couple a months ago I noticed that after downloading the photos on my computer and after viewing them several times , some of them started to show bizarre changes in colors, all of a sudden without any modifications whatsoever from my part - the photos were fine when viewing on my camera, they were also fine just after downloading, I didn't modify them in any way ; here are some examples - I mention that these were totally ok photos before ! any ideas ? please ..............

[krb]

Looks like the files got corrupted. I've seen this kind of thing happen to images coming out of the camera when there's a problem with the memory card. Maybe a bad sector on your computer's hard drive?

[rer]

here is another example

[Thalagyrt]

This is kind of flying off of a wing here, as I've never seen a bad hard drive cause something like that, but with your conditions it's the only thing I can really imagine occurring. I'd say run a low level surface scan of your hard drive to check for any read errors... Seems like data corruption, but not in a very common form. Be careful when looking for low level tools - you don't want a low level format, just a surface scan.

[rer]

but if it's a problem with the card or the hard disk why doesn't it show immediately after downloading the photo ? and when previewing the pictures with picassa or xnview in a thumbnail size you don't see this problem but only when seeing them in fullsize

[rer]

any software suggestion for a low level surface scan ?

[Thalagyrt]

but if it's a problem with the card or the hard disk why doesn't it show immediately after downloading the photo ? and when previewing the pictures with picassa or xnview in a thumbnail size you don't see this problem but only when seeing them in fullsize

If it's a problem with the hard disk, which it likely is, you need to back up all of your data now and then run that surface scan to verify that it's dying or not dying. With a failing hard disk it's only a matter of time until something critical to the filesystem goes kapow and you have to do even crazier methods of data recovery, at which point you've likely irretrievably lost data. They fail gradually, but it's an exponential failure. Slow at first, then it speeds up over time.

Edit: I'd suggest SpinRite to do a surface scan and see what's going wrong. It's not free though...

[krb]

What seems to have happened is that somewhere along the way some bitsoverwritten or&*D&*(FSadded or maybe just rapleced.

The above sentence is an example of what happened to your files. Could be bad sectors on the disk. Could be some kind of operating system issue. Maybe you ran a disk defragmenter that was defective. There's no way for us to guess at what it was and you'll likely never know.

What you are seeing is the reason that so many people are so anal about backing up their data. If you have copied these to another location, such as backing them up to a DVD then you just need to copy them from the backup. if you don't have a backup anywhere then you now know to start keeping backups.

[OdiN1701]

I'd be willing to bet that the RAM in your computer is bad or the hard drive is possilby defective. Most likely a RAM issue though.

[Socket7]

Failing ram or failing hard drive. I'm leaning towards ram. Run Memtest86 overnight and see if you get any errors.

[Thalagyrt]

If it were failing RAM it wouldn't happen consistently on what is only a read operation; specifically viewing the picture. If he's saving it after seeing it that way then yes, failing RAM is a possibility. If they consistently open up the same way it's data corruption on disk. How that data corruption got there is up in the air.

[rer]

I used SpinRite like you suggested, and I noticed something very strange: first I moved all the photos to an external hard disk and I ran SpinRite which showed some errors on the hard disk and freezed without finishing the scan ; afterwards I copied back the photos and I ran SpinRite again , and surprise ! no more errors ! ? ! ?! the degraded photos remained still degraded ; very , very , strange............like if there was some " holes " on some areas of the hard disk which were " filled " by these photos ............. anyway , thanks for your suggestions