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Viewer for broken jpeg images

Forensic software discussion (commercial and open source/freeware). Strictly no advertising.
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Aniskin
Member
 

Viewer for broken jpeg images

Post Posted: Jan 17, 19 14:14

I have some experience in jpeg internals and I created a simple viewer for broken jpeg files. Maybe it will be interesting for somebody.

For example we have a broken jpeg and any standard viewer shows it partially:



But this sample has a thumbnail (or several thumbnails) inside. My viewer knows many ways how thumbnails inside jpeg can be stored (about 20 variants include some proprietary) and my viewer shows the same sample as a mix of the main image and the thumbnail image with max dimension:



The max thumbnail image I saw has dimension 1440x960 so sometimes resulting combined image can have a very good quality.

Link.  

Last edited by Aniskin on Jan 17, 19 16:49; edited 1 time in total
 
  

jaclaz
Senior Member
 

Re: Broken jpeg viewer

Post Posted: Jan 17, 19 15:41

Nice. Smile

If I may, you could rename the thread to something *like*:
New Viewer for broken jpeg images"

I read the current "Broken jpeg viewer" title as "Broken jpeg viewer" in the sense that someone was having a problem with a jpeg viewer that was broken. Shocked

jaclaz
_________________
- In theory there is no difference between theory and practice, but in practice there is. - 
 
  

watcher
Senior Member
 

Re: Viewer for broken jpeg images

Post Posted: Jan 17, 19 17:26

Very nice!

It even runs under Wine with no issues.

Not to complain about free dessert, but if you wouldn't mind a few observations based upon 5 minutes of testing.

The very first thing I think it needs should be easy, and that is a SAVE AS function for the reconstructed image. Other than screen capture, I didn't see a way to do this.

The other observation would be much harder and probably triple the effort of what you've already done which is very useful already. The reconstruction works great on the "End." That is, if I chop off the end of a jpeg to make it broken, it works great. If I take a chunk out of the middle, the reconstruction appears to be only on the end.

Again, very nicely done!  
 
  

Aniskin
Member
 

Re: Viewer for broken jpeg images

Post Posted: Jan 17, 19 17:40

- watcher
The very first thing I think it needs should be easy, and that is a SAVE AS function for the reconstructed image.
It is planned but some later. I want to implement lossless Save As operation, but it requests some additional investigations.

- watcher
The reconstruction works great on the "End." That is, if I chop off the end of a jpeg to make it broken, it works great. If I take a chunk out of the middle, the reconstruction appears to be only on the end.
There is no way to automatically detect you case. IMHO the best solution for this scenario is a special repair tool with which you will be able to do all actions manually. It is requests a LOT of work to create such tool and I don`t have so many free time for free projects.  
 
  

jaclaz
Senior Member
 

Re: Viewer for broken jpeg images

Post Posted: Jan 17, 19 20:21

@Watcher
Side-side note, and don't want to derail the topic, but there is JFYI a mis-known (and actually very primitive) tool that in some cases works (with a lot of tries and providing often not a "proper" reconstruction) even when the corruption is near the beginning (but don't expect miracles):
directory.s2services.c...pg-bmp.htm

Jpeg-repair
by Wim VanMaele

jaclaz
_________________
- In theory there is no difference between theory and practice, but in practice there is. - 
 
  

JaredDM
Senior Member
 

Re: Viewer for broken jpeg images

Post Posted: Jan 21, 19 19:47

Our company offers JPEG repair service for files affected by bad sectors after imaging: www.data-medics.com/jp...-recovery/

It won't help with an image that's half grey at the bottom (such as that one the OP posted) since that means the lower half of the data is just missing, but it will help where it's a case of only some bad sectors and the image has a lot of discoloration, shifts, etc. We simply remove the bad compressed blocks and fill them in with empty placeholders, then fix the color stream.

For people who just want to see their family photos, we'll then fill in the gaps with approximated data. However, for a forensic case, we'd just leave the empty blocks so you'd see some gray lines of empty picture.
_________________
Lead Data Recovery Tech at Data Medics® - www.data-medics.com 
 
  

athulin
Senior Member
 

Re: Viewer for broken jpeg images

Post Posted: Jan 21, 19 20:20

- Aniskin

The max thumbnail image I saw has dimension 1440x960 so sometimes resulting combined image can have a very good quality.


Nice.

From a forensic perspective, however, I think it need to be clearer that a restoration has taken place, and what part (or parts) have been restored. This would be particularly important for a 'save as' operation.

On the other hand, I don't know that's the direction you want to take it -- i.e. forensic tool.  
 

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