Hello again,

Sorry for having disturbed the list prematurely!

I found a very easy solution: I noticed that greping for "Exif" in the dd output gave me the exact start of new image data. Now, I can export all these offsets, calculate the data sizes for each picture and copy the picture data into files with dd .

Several tests gave good results while so far I found apparently truncated data in one place; however, the result will be better than losing everything.

Greetings,

Jean-Jacques

Jean-Jacques MOURIS wrote:

Hello,

I have been asked by a friend for help with an SD-Card which apparently is corrupted, to rescue the 120 pictures stored on it , if possible. Apparently, the camera repeatedly asks the user if it should or not reformat the card.

So I first tried to mount that card into my system, using an USB card reader. Unfortunately, I found no matching filesystem to do so; in /var/log/messages, I found errors like :

Jan 11 22:12:55 niepce kernel: FAT: invalid media value (0x3f)
Jan 11 22:12:55 niepce kernel: VFS: Can't find a valid FAT filesystem on dev sdf

So, the filesystem obviously seems to be damaged !

Then, I tried reading out the card with dd into a file, which gave me, as expected, a 256 MB file:

dd if=/dev/sdf of=/data/tmp/secdig.dat

In this file, I searched for typical data like dates or other typically EXIF data, which brought partial results:

hexdump -C secdig.dat | grep 2007

0290c0c0 56 65 72 2e 31 2e 30 20 20 00 32 30 30 37 3a 30 |Ver.1.0 .2007:0|
0290c350 d0 07 00 00 1c 00 00 00 0a 00 00 00 32 30 30 37 |............2007|
0290c370 32 30 30 37 3a 30 38 3a 31 39 20 31 30 3a 32 39 |2007:08:19 10:29|
02920070 48 59 7e 64 27 a6 e5 ef 5d d8 55 08 cd c9 f5 32 |HY~d'...].U....2|
02a20070 97 12 ea 1a 8e 8f 36 a1 bf 5f b2 68 de 58 e3 96 |......6.._.h.X..|
02ab80c0 56 65 72 2e 31 2e 30 20 20 00 32 30 30 37 3a 30 |Ver.1.0 .2007:0|
02ab8350 d0 07 00 00 1c 00 00 00 0a 00 00 00 32 30 30 37 |............2007|
02ab8370 32 30 30 37 3a 30 38 3a 31 39 20 31 30 3a 33 35 |2007:08:19 10:35|

After comparing some data to intact pictures of my own, I noticed that the data seemed to represent intact picture data, as far as the Exif part of the pictures is concerned, the actual picture data being of course uninterpretable.

Now, I would be very grateful if somebody could give me any hints how I could possibly recover the image data contained in the dump or if there is any way to use these data in a way that would enable me to get back the data.

Any help will be greatly appreciated.

TIA

Jean-Jacques Mouris
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