Bill Funk <> wrote:
> On Sat, 22 May 2004 18:31:40 GMT, Ian Stirling
> <> wrote:
>
>>Bill Funk <> wrote:
>>> On Sat, 22 May 2004 13:34:55 +0000 (UTC), "Beck"
>>> <> wrote:
>>>
>>>>
>>>>"Tama Mativa" <> wrote in message
>>>>news:40af47e2$0$31675$ om.au...
>>>>> Last week i formated my CF card accidently and was trying to recover the
>>>>> photos
>>>>>
>>>>> I bought a Card reader and used the program "Zero Assumption digital image
>>>>> recovery" and got back all the photos
>>>>>
>>>>> thanks to everyone for the suggestions
>>>>>
>>>>> http://www.z-a-recovery.com/download.htm
>>>>
>>>>After you accidentally formatted the card, did you take more photos to it,
>>>>then try and recover the photos?
>>>>Just curious as to how deep the program is able to recover programs, and
>>>>whether it can recover AFTER the card has been written to.
>>>
>>> I've used ZA on several cards...
>>> It's like any other consumer file recovery utility in that it's not
>>> going to recover overwritten files.
>>> If the file is intact, there's a good chance ZA will recover it, even
>>> after a format.
>>>
>>> I haven't seen any consumer products that will recover overwritten
>>> files. Has anyone?
>>
>>Well, I've used csplit/... unix tools to do it.
>>If the camera does not store as fragmented files (as most do not)
>>then by simply splitting a copy of the raw device into files every time
>>you see something that looks like the start of a jpeg works well.
>
> I'm sorry, but I don't understand this.
> More precisely, what does "raw device" refer to?
Sorry.
Most flash devices are arranged as a linear collection of 512 byte
sectors.
If you simply read all the sectors in sequence without taking account of
the filesystem, then you get a raw image of the device.
This isn't particularly useful in general, as you want to store more
than one file on the device, and know where it is.
So, this raw device is formatted in a certain way (FAT, ...) which
tells you where the files are.
However, even lacking this information, most devices if starting
from a freshly formatted filesystem (or turned off after deleting files)
will start to write files in continuous blocks, one after the other.
If you split the copy of the raw device at the points where the sequence
of bytes indicates a new file (for example GIF files begin with
GIF89a (or similar)) then you can recover most of the pictures.
If files are individulaly deleted, this causes problems, as then if
more are taken, the new file will go into the gap left, with
bits left over going somewhere else, so this new file cannot easily
now be recovered this way.