corrupt photos?

thequeenscheese

Senior Member
so ive just copied over from the camera to the pc and most of my holiday snaps are being reported as unknown file types by nx2, pro optics 8 couldnt open them because it says the EXIF data cannot be read or is corrupted, but a few are ok and one random pic i took this morning is ok?

ive also previously just formated the card in the camera which is a bummer..

a couple of times when shooting on holiday the camera did say poblem with sd card but after turning on/off and remoing reinserting the card it was fine and it only happened a couple of times but it has happened previously with my 32gb lexar micro sd also which is why i swapped back to my smaller slower 16 gb sandisk class card.
any ideas?

individual propertys seem to show each pic with a filesize of 7.56gb-which seems quite random?

any help appreciated thanks
 

thequeenscheese

Senior Member
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thequeenscheese

Senior Member
exactly i need to 1, un-format the sd card - any ideas on a program thats free to do that and will let me do the whole card not just 1 gb? and 2 uncorrupt the files if they are corrupted and fixable?
 

Marcel

Happily retired
Staff member
Super Mod
Did you actually copy and paste your nef files or did you try importing with NX2? If I was you, I'd put the card back in the camera and open NX-2, plug the usb wire to the cam and try importing the files straight with NX-2. Have you tried opening the files with another program? Are your jpegs OK from that session? Since you see the previews, I suspect you might have workable jpegs if you did shoot Raw AND Jpeg.
 

WayneF

Senior Member
individual propertys seem to show each pic with a filesize of 7.56gb-which seems quite random?


Are you formatting the cards IN THE CAMERA? You should. Memory cards are FAT32, but Windows can format them in in other ways (which the camera cannot use). The Maximum file size that can be created or reported in FAT32 is 4 GB (30 minutes of HD movie can reach that file size, but still pictures cannot).

Format memory cards IN THE CAMERA. The camera knows what it is doing.
 

WayneF

Senior Member
Such corruption problems can be the card, or it can be the card reader. If reading the card directly in the camera, it's not a reader. Not impossible it could be the computer USB port, but we don't hear of that (you could try a different port).

So you should try a different card (formatted in the camera).


FWIW, when you plug it into the computer, it becomes a disk drive, like F: or G:, etc.
My Computer will show the current drive letter.

At a windows command line, you can run chkdsk (Check Disk)
typing like: chkdsk G: (as appropriate).

It will report any errors on the card. There must be plenty, which however could be a communication issue with the computer (a card reader, etc).

You can run chkdsk /? which will show a menu of the available commands.

chkdsk /F will attempt to correct those errors (may lose the data instead of correcting it, but it is a common practice on a computer disk, but for the card, reformatting in camera is surely better. Or a new card if needed. )
 
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thequeenscheese

Senior Member
any idea how to un-format?, im guessing the origional files are ok and its the copy over process is whats guffed up
ive just ran a recovery but thats not found any nef files which is what im missing it found some old jpegs i did when i got the camera, but i dont want to recover those in fear of loosing everything else..
 

WayneF

Senior Member
any idea how to un-format?, im guessing the origional files are ok and its the copy over process is whats guffed up
ive just ran a recovery but thats not found any nef files which is what im missing it found some old jpegs i did when i got the camera, but i dont want to recover those in fear of loosing everything else..

If you think it is a transfer communication problem, then try transfer again, in other ways. Different USB ports, a different card reader, a different computer, etc. No repair on the card would help that.

Assuming Windows, and that the card is currently for example computer drive letter E:, then:

chkdsk E: will check and report errors on the card.

Or then, chkdsk E: /F can attempt to repair it, and can fix some issues, but can also lose some corrupted data trying. It puts the data it knows it loses into other hidden files on the disk. If plain text data (recognizable to the eye), recovery to some extent might be possible, but generally its gone.

Another format will simply replace the FAT with all blank entries, i.e., all your data is lost.

But reformat (in the camera) is the simplest and best way to clear your card to be empty (each time after you successfully transfer your images). It is Good to take time to check your image transfer is OK before you format the card again.

In the case of a memory card, a new card is probably the correct action if chkdsk reports much error. Chkdsk is for hard drives, where simple replacement is a less feasible choice. However, chkdsk also has to communicate with the card in the same way data transfer accesses it.

How FAT works:

The disk device (the memory card) has a small FAT area at the top (File Allocation Table). This is a small table (an entry for each file present) that has the file name, all the various dates, the file size, attributes like Hidden or Read Only, and the location where the file data begins on the disk. Each disk cluster of data has a pointer to where the next cluster is located. If you see the impossible 7GB, this is very much corrupted. FAT32 is 32 bits which holds numbers (a cluster count) up to 4GB files, but simply cannot store a 7GB number. 7GB means something is bad wrong. NTFS in the computer can hold larger files, but the card is FAT32.

Recovering old JPG files would not have any adverse effect (and would not help anything about this problem).
When one file is deleted, the only change is that the first letter of the file name is replaced with a tilde ~. This means deleted, and it becomes invisible, however nothing is deleted. Its space (FAT table and the file space) is declared free and available, and some new file can be written over it, but until then, there are utilities that can recover it (simple undelete), by searching for the tildes and then "reading" it, if not yet written over. Undelete utilities have to ask you for the real first letter of the file name.

Probably not helpful here, but FWIW, see https://technet.microsoft.com/en-us/library/cc938438.aspx for some FAT details.

When we reformat a card, the FAT table is simply cleared, all zeros... which declares the entire card is now available - no files on it now. But nothing else happens, the data is not affected (by a simple format... but low level format writes zeros over all of it), and rather sophisticated tools might still recover some of it (until overwritten with new files). But not if it is corrupted.
 
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Marcel

Happily retired
Staff member
Super Mod
any idea how to un-format?, im guessing the origional files are ok and its the copy over process is whats guffed up
ive just ran a recovery but thats not found any nef files which is what im missing it found some old jpegs i did when i got the camera, but i dont want to recover those in fear of loosing everything else..
If you did re-format after you copied your files, then you're in big huge trouble and I don't think you'll be able to recover these shots.

Now, before you go to extreme lengths about these shots, ask yourself how important they are. Was this a paying job? Would you loose money if the pictures were forever lost? If you answer NO to these two questions, then just forget about it for now. BUT, now would be the time to do some trials (before the next problem happens) and test your card and/or computer port connection.

I've read a few times where people got burned with fake sd cards. It could happen to all of us. The cards do look legit, but they contain a micro sd card inside and a lot of times they do not have the real memory content that they should. I think there are ways to tell if your card is real or fake but I don't remember how to do just that.

I hope you can solve this and get a good and proven way to copy your pictures to your computer in the future. And, for what it's worth, why not shoot RAW AND JPEG just to be safe...

Good luck.
 

thequeenscheese

Senior Member
i sorts know most of what youve said already, but am unsure on how to/best way to remove the "~" i calle dit unformat/recovery just was unsure if same process, so know i need a recovery agent thats free and will recover the whole card not just a 1gb snipit without having to upgrade to a full paid version..

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WayneF

Senior Member
i sorts know most of what youve said already, but am unsure on how to/best way to remove the "~"

That is what undelete programs do... checks the files starting with tilde for consistency, and if consistent, then they rewrite the first letter you give it over the tilde. That causes the file to be visible and present again. Nothing else happens, the file is already there.

But your files are not deleted, they sound corrupted somehow. Except the chkdsk you show says they are not. It says the card has one 32K file? I'm thinking that must be the DCIM file (a folder is a file), and that the card has already been reformatted.
 
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Horoscope Fish

Senior Member
I'll just point out doing an in-camera "reformat" does NOT reformat the cards file structure (FAT32). The only thing an in-camera reformat "reformats" is the FOLDER structure (i.e. DCIM/D3200 etc.) used by the camera to store photos. These are two HUGELY different things.

To properly reformat the SD Card (which *WILL* over-write all the data and re-create the File Allocation Table (FAT)), you need to do the following:

Put the card in a computer media reader.
Wait for the card to mount as an available drive.
RIGHT-click on the card and select "Format".
Clear the check-box for "Quick Format".
Click "OK".
You'll get a warning about erasing your files.
Continue with the format.
Go make a cup of tea because this is going to take a while.​

On my Core i7 computer at home with 16GB of RAM, reformatting a 32GB SD card takes about half an hour. I assure everyone our Nikon DSLR's are not performing this same feat in a fraction of a second when we "reformat" our SD cards in-camera. Lastly and speaking only for myself, any card that fails to re-format properly in my computer, or gives me any kind of error message in-camera, even once, gets exchanged for a new card, or the card gets trashed. They get no second chances, ever.
.....
 

WayneF

Senior Member
To properly reformat the SD Card (which *WILL* over-write all the data and re-create the File Allocation Table (FAT)), you need to do the following:...


But there is absolutely no point of clearing the entire card (other than possibly security). OK, it does check for bad sectors and removes them from the disk map (more important for magnetic media than for semiconductor memory cards). But a quick format clears the FAT, which forgets about all files. The file area can be rewritten, and there is no advantage of it being zero before rewriting it. Zeroing all bytes just adds to the writing count (supposedly reducing card lifetime, and certainly increasing the time to do it). It offers no advantage.

And it should be formatted in the camera, which adds an extra file or two (the Nikon DCIM, etc), which also gets recreated by just turning the camera on, but the camera knows exactly how the card should be formatted. Users at the computer may or may not know.
 
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thequeenscheese

Senior Member
of course the camera is doing a quick format marking the files as being able to be written over i dont think anyone is confusing this, and its why im trying to get the raw pics back from the card still, as wayne said while i was writing.
 

WayneF

Senior Member
There are utilities to recover disks after reformat, assuming not written over or corrupted.

recover formated disk - Google Search

I have no experience with anything other than undelete, which starts from the FAT. Absent a FAT (after reformat), then there are utilities that can search for tops of chains, and recover them to the end. They do not know a correct file length from the FAT however. It is not as failsafe as undelete.
 
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