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Repair Damaged JPEG/CRW Files

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Anonymous
July 13, 2005 6:04:28 PM

Archived from groups: rec.photo.digital (More info?)

I have a computer with a 160 gigabyte hard drive. Being tempermental as I
sometimes can be, yesterday when the computer ran extremely slow despite
numerous reconfigurations, I pretty much demolished it. Not totally, but
pretty much. Man, that temper of mine!


Anyway--yes, you know where this is going--I actually had backed up almost
all my photos. Everything I've ever done right up til July 1st was backed
up. But needless to say there have been a few losses. Most of what I've shot
since July 1st actually I have recovered (hooked the hard drive up to the
other computer and starting recoving those files and burning them to DVD+R
discs). But a few are there but dont open properly, they appear corrupted.

They definitely are there, the file size is large and analogous to what the
type of file is. But when you double-click it it won't open because it's
"corrupt."

What methods can help "uncorrupt" such a file? Again, some of these are CRW
files. PS--I open the files with Infranview 3.91, and it will show the
"embedded" JPEGs shot by the 300D camera.

PS--I have tried some software packages, almost of all them insist on
scanning every inch of all hard drives, I just want one that lets me
immediately jump to the file(s) in question, click on them and select "Fix"
or whatever. One program (Restorer 2000) does, but not the free-one--it
wants me to do the NTFS package, which costs--and my credit card has no
funds on it.

LRH
Anonymous
July 13, 2005 8:23:31 PM

Archived from groups: rec.photo.digital (More info?)

Larry R Harrison Jr wrote:

> What methods can help "uncorrupt" such a file? Again, some of these are CRW
> files. PS--I open the files with Infranview 3.91, and it will show the
> "embedded" JPEGs shot by the 300D camera.

If the file recovery tool adds even 1 byte to a CRW file, it is
undecodable with naive decoders (ie, almost everyone). Typically in
these cases there is (much) more than 1 byte -- you'll probably find
your 'corrupt' files have a length that is a multiple of the
filesystem's blocksize.

Your job is to find the "real" end of file and truncate it at that
point. Get a hex editor, examine a number of good CRW files and look
at the end of the file: there is a distinctive pattern. Then aim said
editor at the corrupt file(s), locate this pattern and use the editor
to truncate everything beyond that point.

You may wish to work against copies to prevent ghastly mistakes.
Anonymous
July 13, 2005 10:54:56 PM

Archived from groups: rec.photo.digital (More info?)

"Larry R Harrison Jr" <noone@noone.net> wrote in message
news:5nfBe.8762$Eo.2975@fed1read04...
>I have a computer with a 160 gigabyte hard drive. Being tempermental as I
> sometimes can be, yesterday when the computer ran extremely slow despite
> numerous reconfigurations, I pretty much demolished it. Not totally, but
> pretty much. Man, that temper of mine!
>
>
> Anyway--yes, you know where this is going--I actually had backed up almost
> all my photos. Everything I've ever done right up til July 1st was backed
> up. But needless to say there have been a few losses. Most of what I've
> shot
> since July 1st actually I have recovered (hooked the hard drive up to the
> other computer and starting recoving those files and burning them to DVD+R
> discs). But a few are there but dont open properly, they appear corrupted.
>
> They definitely are there, the file size is large and analogous to what
> the
> type of file is. But when you double-click it it won't open because it's
> "corrupt."
>
> What methods can help "uncorrupt" such a file? Again, some of these are
> CRW
> files. PS--I open the files with Infranview 3.91, and it will show the
> "embedded" JPEGs shot by the 300D camera.
>
> PS--I have tried some software packages, almost of all them insist on
> scanning every inch of all hard drives, I just want one that lets me
> immediately jump to the file(s) in question, click on them and select
> "Fix"
> or whatever. One program (Restorer 2000) does, but not the free-one--it
> wants me to do the NTFS package, which costs--and my credit card has no
> funds on it.
>
> LRH
>
>

The problem here is that you did not 'FIX' the computer well enough, if you
had, you would not be concerned with recovering files. Use a larger tool
next time, its infinitely more satisfying. You want to see small parts
flying, a veritable cloud of floating debris. Very primal.

R.
Anonymous
July 14, 2005 12:44:29 PM

Archived from groups: rec.photo.digital (More info?)

Larry R Harrison Jr wrote:

> Anyway--yes, you know where this is going--I actually had backed up almost
> all my photos. Everything I've ever done right up til July 1st was backed
> up. But needless to say there have been a few losses. Most of what I've shot
> since July 1st actually I have recovered (hooked the hard drive up to the
> other computer and starting recoving those files and burning them to DVD+R
> discs). But a few are there but dont open properly, they appear corrupted.
>
> They definitely are there, the file size is large and analogous to what the
> type of file is. But when you double-click it it won't open because it's
> "corrupt."

That doesn't mean they are definitely there - it just means that the
directory entry has reserved about the right amount of space. You can
roughly test whether a JPEG is plausible by trying to recompress it with
ZIP. If it compresses by more than about 5% then the file is almost
certainly wrecked. More often than not you have huge chunks of misplaced
Windows swap file masquerading as image data.

Check previous threads for software that can make a reasonable stab at
image recovery - things like PhotoRescue.

> PS--I have tried some software packages, almost of all them insist on
> scanning every inch of all hard drives, I just want one that lets me
> immediately jump to the file(s) in question, click on them and select "Fix"
> or whatever. One program (Restorer 2000) does, but not the free-one--it
> wants me to do the NTFS package, which costs--and my credit card has no
> funds on it.

Damaged JPEG images with real commercial or forensic value can sometimes
be (at least partially) recovered if it is absolutely essential but the
process is time consuming and not cheap. JPEG streams are quite tricky
once they get damaged - it is part of the price for good compression.

Nothing beats having a good backup.

Regards,
Martin Brown
!