What causes this sort of RAW file corruption?

Question

I came home from a recent trip to Gettysburg with almost 1500 photos. Among them were a handful that appear to have been corrupted, as shown below. It was hot during the hikes -- ambient temperature was near or above 100 Fahrenheit, so I suspect the heat contributed to the problem.

These files exhibit some interesting behavior:

• When I view them in Lightroom or Windows Explorer, the files show normally for a split-second, then are over-painted with the light area you see below.
• If I try to open the file in Canon's Digital Photo Professional, the thumbnail view shows the complete (uncorrupted) file, but DPP refuses to open the files for processing, saying that they're corrupt.

I haven't tried to figure out if all the files came from the same card, but all cards were formatted in-camera prior to the trip.

I don't believe I've lost anything important at this point, as I shot multiple frames of most subjects, but I'd really like to know what caused this problem, and what, if anything can be done to resurrect these files.

Answer 1

I can only answer your second question - i.e. if anything can be done to resurrect these files. As others have mentioned, that uncorrupted version you're seeing briefly as you import them into Lightroom is the preview JPEG generated in-camera when you shoot RAW. There are plenty of tools that will recover those previews for you, hopefully even if the RAW file itself is corrupted. (The fact that you're seeing the previews in other software is an encouraging sign.)

Check this accepted answer for a list of software. I've tried dcraw and it worked a treat.

Good luck!

Answer 2

This is often down to transfer from card to computer, not corruption on the actual card.

I have found that Windows Explorer tends to be the culprit - do not copy files from your card simply by dragging/dropping in Explorer - use a different tool.

I have used the free 'FastCopy' file copier with 100% success. It has a verification option that you can use to confirm the files copied correctly.

ps. Don't rely on the CR2 preview in explorer (if you have this shell extension enabled) because it uses the embedded preview which may be fine. To test all files in a folder, I run the Adobe DNG converter to convert to DNG files, then use the DNG shell extension (google it) to preview in explorer. This shows up corrupt DNG files (from corrupt CR2 files) easily. Then you can go back and recopy those individual files from your flash card. But I've not had this problem at all since switching to FastCopy.

Answer 3

Most likely causes are a bad SD card (or at least one that needs formatting) or card reader/cable. Evan Krall posted a good link there.

Easy way to test is to get a different card and shoot a few hundred photos on it and see if the same happens. You mentioned the heat in your post; manufacturers do sometimes warn about what temperatures can affect electronics but I've not heard of it ever happen outside of the extreme cold but it's certainly a possible factor.

As for recovering the files: it may not be possible. There are a few software vendors out there making applications for this sort of thing but I've never tried them and can't vouch for any of them but this is a high-ranking one in Google: http://www.crwrepair.com/. I'd give this a quick look too especially as it's a free tool: http://eirikso.com/2009/03/23/how-to-rescue-images-from-a-corrupted-cf-card/

Of course, it's always worth seeing if it's a problem with the software you're using and not the actual RAW file first. Try opening the image using Adobe Camera RAW or another app just in case. Hope you get your photos back and enjoyed the trip to Gettysburg :)

Answer 4

I think you have two questions:

• what causes the file corruption:

bad flash memory, 80% of time.

• When I view them in Lightroom or Windows Explorer, the files show normally for a split-second, then are over-painted with the light area you see below. Why?

Normal. A raw file usually embed a preview JPG and the program (OS, Lightroom etc) will first display the JPG, and then tries to render the raw file.

Answer 5

Possible causes of the problem.

1. The memory card used is does not meet the standard requirement of the DSLR, e.g. (the required SDCard should be class 6, but the installed is of lower class). This can be a critical factor that's why it is wise to check the requirement first before buying. Not all memory cards are the same.

   2. The Memory card is damaged. External factors are possible, but there is also one possible software factor. When you use a file recovery software, what it does is (in layman's term) it destroys the latest electronic layer (which means the latest files) to retrieve the deleted files. Few background: When formatting the memory card, the files were not really deleted but rather it creates a new usable layer to cover all the previous files, thus the new layer will cater new files that will be store there. It is not advisable to regularly use a file recovery software, chances are, it will damage the memory card.

   3. Use the proper tool when transferring the photos from the card to the PC. A "drag-and-drop" method is NOT RECOMMENDED. Use the USB cable to connect the camera to the PC and the software provided by the manufacturer to ensure the quality of files during transfer.

Answer 6

Possible causes:

Bad CF/Flash card

Power surge

Cellphone interference (never keep your card in your pocket next to your phone)

Microwaves (This happened to me at a factory once)

File transfer (try importing again)

Gremlins (They really do live in cameras)

Answer 7

Maybe pre-embedded virus in the cards, most likely from less popular brands; the same people that sell you raw file repair software.

Sure, people would exchange the cards in fear of them being defective. But some pictures people lose can be very valuable which most likely covers the returns.