RAW file from image?

puzzledpaul

Reverse RAW converter.

More or less as title - does a means / software exist to allow a RAW file to be created / generated from a 'finished' image - such that the RAW file would exhibit all of the characteristics of a file produced by any particular camera?

pp

Richard

Nope. Take a look at this thread: http://www.dgrin.com/showthread.php?t=181501

puzzledpaul

Thanks for the link - interesting read, even though there was relatively little info about the 'nuts'n bolts' of why it's not possible - as opposed to dealing with the specific reason the OP raised the topic.

pp

ziggy53

A genuine Bayer chip RAW file contains the (close to) original data acquired by the camera's imager and still in "mosaic" and linear form.

Once the RAW data has been processed, either in-camera or in software, it no longer contains the original data and it is a subset of the original data. The Bayer array information has been demosaiced and the tonal values have been expanded into a more visually "normal" range. Normally, white-balance/color-balance has been applied and the data has been adjusted to fit a specific dynamic range.

Trying to reverse a process where you are working with a data subset means that you could only "mimic" a portion of the original. You can never gain back the original data lost in processing.

Internaut

Another good reason to shoot raw, even if you're mostly a JPEG shooter then..... Surely being able to produce a raw capture is the gold standard when it comes to proof of ownership?

colourbox

puzzledpaul wrote: »

Thanks for the link - interesting read, even though there was relatively little info about the 'nuts'n bolts' of why it's not possible - as opposed to dealing with the specific reason the OP raised the topic.

Let's put it this way...it's like walking into a bakery and asking them to un-bake a loaf of bread into its original virgin ingredients, water, flour, eggs, etc. It's simply not possible to go backwards that way.

Matthew Saville

The best you can do is to process a JPG file in Bridge or Lightroom and use the same processing parameters as you would for a RAW file. You won't get the ACTUAL white balance etc. back, but at least the adjustment sliders will be familiar.

Just another reason to shoot anything important in RAW. Especially if you use Nikon, seriously a compressed RAW file is on average almost the same filesize as the highest quality JPG. In fact I've had shoots where a couple of the JPG files surpass a couple of the RAW files!

So as a Nikon user I would never shoot JPG to save storage space, the difference is negligible. If anything, shoot compressed 12-bit RAW most of the time, and un-compressed 14-bit for landscapes or whatnot. I shoot 12-bit compressed RAW files for almost everything, even wedding / portraiture work.

The only reason I shoot JPG is when I'm goofing around with friends / family, and I know for a fact that I want to treat my camera like a polaroid camera. I abstain from any processing, and just upload the image straight, and it's fun that way. It challenges me to nail my in-camera settings. (I've been blogging about that a lot lately, actually. :-)

=Matt=

fdisilvestro

Yes, it can be done. There is a proof of concept here

puzzledpaul

Back story.

I was at a local venue yesterday shooting wildlife and ended up with half a doz frames of a different sort of 'wild' life than usual
A couple of youths, riding around on a small, noisy motorbike (in a venue where it's prohibited) who'd been annoying everyone else around out enjoying the sun (a rare yellow orb here) - I heard them coming along the track near me and got said shots.
After mentioning this to a long term friend (ex local gov worker) ... who's also a (responsible) biker ... he enquired whether there was any way the Raw conversion process could be reversed, because of the 'evidence' ramifications, should the veracity of said shots ever be questioned.

pp

davev

So let me get this straight, you want to make a raw file from a jpg to prove that you have an untampered file?
Am I the only person seeing a problem with this?

Surely 6 shots of the same people, in the same clothing, on the same machine, in the same place, would show the "crime".

As for proving ownership, as a jpg shooter, I crop at least a little off of every photo I put on the net.
It's real easy to show how well that image fits into the original.

I did find this article of what can be used in court, but it is a few years old, things may have changed by now. LINK

If you have a link showing that jpg's aren't admissible, I'll like to read it.

colourbox

An expert will probably be able to tell the difference. The noise added by the back-converter would have to precisely match the exact noise signature of the camera at the given settings. Since JPEG is limited to 8-bit, there may be obvious tonal/color losses that cannot be re-invented on the way back to a 10-16 bit Raw file, especially in the ranges that JPEG hits the hardest. And of course, if the JPEG had any JPEG compression artifacts at all, they would need to be removed convincingly.

puzzledpaul

<< So let me get this straight, you want to make a raw file from a jpg to prove that you have an untampered file? >>

No.
I shoot RAW, so have the relevant RAW files and whilst I'm somewhat familiar with the RAW/ jpg 'debate', my friend isn't - so, playing 'devil's advocate' - he asked, what to him - seemed a reasonable (theoretical) question 'is it possibe to create a RAW file from an image?

So, if a 'jobsworth' type of local civil servant who was presented with a supposedly unique piece of 'evidence' (an original, normal RAW file) could be told an unequivocal NO if they should query whether said RAW file could have been generated / created from a 'doctored' image. (assuming jobsworth has heard of photoshop and 'how all images are fiddled with these days, aren't they?' ... level of understanding)

Whilst I believed it was an irreversible process, it seemed a fair Q to ask

As regards this specific situation, I'll just ask one of the rangers next time I see them ... and enquire whether they want to be bothered to do anything ... or not.

pp