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Question about extra-large JPG

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Interviewer: Is there anything you don't like?
Bjarne Stroustrup: Marketing hype as a substitute for technical argument. Thoughtless adherence to dogma. Pride in ignorance.
-Eóin (December 22, 2011, 02:57 PM)
--- End quote ---
Wow! That is a totally awesome quote! I'm going to leverage curation using that quote to increase my big picture visibility and give persistence to my whitespace social media presence, going forwards.

(Sorry. Couldn't help myself.)    :-[

big picture visibility
-IainB (December 22, 2011, 08:02 PM)
--- End quote ---
Awesome; you even stayed on-topic! ;D

It was too good to resist...
...but back to business:

I have had a look at these 3 files using IrfanView and PhotoMe.
Files 0000.JPG and 0001.JPG seem to be OK, but have no EXIF data.

When trying to open file 0065.JPG:

* IrfanView says: "Decode error ! Bogus marker length."
* PhotoMe says: "The JPEG header of the selected image file is invalid."
Taking a look at file properties for all 3 files, they each have this oddity in common, at least: (I've never seen this before)
This file came from another
computer and might be blocked to
help protect this computer.
--- End quote ---
I selected "Unblock" for file 0065.JPG, but it seemed to make no difference.
Looking at file 0065.JPG with a text viewer (EditPad Lite) showed no interesting patterns or text strings.

I downloaded a trial version of Stellar Phoenix JPEG Repair and ran it on the file twice, but the proggy crashed each time, after quite a while scanning the file.

I did find this link, that might be of use: Repair Corrupt JPEG File by help of Hex Editor

JPEG files have designated areas for storing data. If the file is that large, then likely there's some garbage or null data somewhere. If you can simply recover the image then save it at 100% quality, you should be good.

I've had trouble opening some images with Irfanview in the past. That was simply because Irfanview skipped some error checking and just puked on some bad images. The data is still there, and some programs do check for those specific errors in images.

Anyways... don't worry too much about the massive file. Just recover it, then delete it.

I need to get some work done, so I can't check the files directly... Sorry... But I hope the above helps somewhat.

The large size of the files is almost certainly due to the recovery process. Most likely the recovery apps put some garbage/unrelated data inside of the JPG file blob, meta descriptors, etc. but not in such a place that it makes the image unable to load (fortunately!). If it were me I'd just batch convert them all to a lossless format (e.g. PNG), or a "max quality" (100 in many apps) JPG if nothing else, keeping in mind that even a max quality JPG is still lossy. You could do batch conversion with e.g. XnView.

Opening these images in XnView and doing a JPG lossless transform (e.g. rotate right) shows that the garbage data hypothesis is most likely correct. The image size dramatically reduces to around 300KB and the images look identical (as they should). In theory this is a totally lossless transform process, and no JPG recompression options are offered, so unless it's defaulting to something without notifying, I assume it hasn't recompressed.

I definitely recommend XnView as a powerful, versatile image processing and conversion app that can likely deal with these issues.

(standard disclaimer: I am not affiliated with XnView, just a huge fan and long-time user :D)

Update: finished downloading the other images and unfortunately XnView does not open 0065.JPG, so evidently it can't take care of this problem for all your images. If you have something else that opens 0065.JPG, use that to convert. XnView does fortunately work for the 120MB JPG.

- Oshyan


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