Recovering Corrupt Jpegs

I've seen a number of posts about retrieving deleted jpegs but haven't
found much useful information on how to recover a corrupt jpeg.

Here is my problem. I have a number of photos in jpeg format that were
stored on a RAID 0 stripe set. There seems to be some issue with the
RAID configuration (I have 4 machines that have done the same thing).
A number of the jpegs started to get corrupted over time. The images
are only partially visible and the rest of the image is displayed as a
gray area.

I tried using scandisk and managed to recover parts of some of the
photos but not all of them.

The thumbnails of the images are fully visible in ACDSee (but not any
other program). There has been no noticeable change in the size of the
image file.

From all I've gathered off the web it seems as if changes in the
header information could corrupt the file. Is there any tool out there
to repair such corrupt jpegs?

Thanks

Sanjay

P.S. I don't want to recover a deleted file but repair a corrupt jpeg

The thumbnails of the images are fully visible in ACDSee (but not any
other program). There has been no noticeable change in the size of the
image file.

This app keeps its own thumbnails, try to press F5 in the folder to refresh
them and you will get them corrupted as well because they will be refreshed
using the current files. If you have the images interlaced, then it could be
a different picture, but anyway you need to keep at least 2-3 copied of your
stuff. Get your own sad experience!

Just D.

On Feb 6, 9:32 pm, wrote:
I've seen a number of posts about retrieving deleted jpegs but haven't
found much useful information on how to recover a corrupt jpeg.

That is because it is a hard problem, and only soluble in certain
limited cases by the application of large amount of computing power
and some intuition. A few bits flipped in the wrong place in a JPEG
file can render the entire file after that point unreadable by most
codecs. Typically corrupt JPEGs if they will display at all show grey,
black or crazy patterns or the image pastel or psycadelic colours with
various lateral shifts.

Web browsers are about the most tolerant of corrupt streams of
commercial applications. PhotoShop is the most unforgiving.

Here is my problem. I have a number of photos in jpeg format that were
stored on a RAID 0 stripe set. There seems to be some issue with the
RAID configuration (I have 4 machines that have done the same thing).

Are you sure it isn't a virus then ?

A number of the jpegs started to get corrupted over time. The images
are only partially visible and the rest of the image is displayed as a
gray area.

That is characteristic of what happens when parts of the file are no
longer realy there (despite what the directory entry may say).

I tried using scandisk and managed to recover parts of some of the
photos but not all of them.

The thumbnails of the images are fully visible in ACDSee (but not any
other program). There has been no noticeable change in the size of the
image file.

ISTR ACDSee makes a private cache of the thumbnails so that is no
guide.

It is a very bad sign that no other program can see thumbnails in the
corrupt files. Most times the header does survive well enough to
display a thumbnail, it is only when you try to open the main image
that the application finds the stream is corrupt.

From all I've gathered off the web it seems as if changes in the

header information could corrupt the file. Is there any tool out there
to repair such corrupt jpegs?

Not at present, although I am working on one. A crude test of whether
there is anything left to recover is to try ZIP compressing a few of
the damaged images. If they will compress by more than 5% then they
are probably gone forever.

I'd be willing to take a look at 3 consecutive corrupt images to see
if there is any prospect of repairing the damage.

Regards,
Martin Brown

Martin Brown wrote:
On Feb 6, 9:32 pm, wrote:
I've seen a number of posts about retrieving deleted jpegs but
haven't found much useful information on how to recover a corrupt
jpeg.
....
From all I've gathered off the web it seems as if changes in the

header information could corrupt the file. Is there any tool out
there to repair such corrupt jpegs?

Not at present, although I am working on one. A crude test of whether
there is anything left to recover is to try ZIP compressing a few of
the damaged images. If they will compress by more than 5% then they
are probably gone forever.

I'd be willing to take a look at 3 consecutive corrupt images to see
if there is any prospect of repairing the damage.

Regards,
Martin Brown

Try
http://www.datarescue.com/photorescue/
Their professional tool version can rebuild damaged files.
--
AsleB;Oslo, Norway

--
___________________
EDW SPA



"Just D" wrote in message
...

The thumbnails of the images are fully visible in ACDSee (but not any
other program). There has been no noticeable change in the size of the
image file.

This app keeps its own thumbnails, try to press F5 in the folder to
refresh them and you will get them corrupted as well because they will be
refreshed using the current files. If you have the images interlaced, then
it could be a different picture, but anyway you need to keep at least 2-3
copied of your stuff. Get your own sad experience!

Just D.