editing a raw file secretly

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#1
hi all

quick question that i can't seem to find the answer to........

is it possible to edit (photoshop) a raw file without anyone being able to detect that it was tampered with?

any help/advice much appreciated

d.
 
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wayne clarke
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#2
Ithink we'd need more information, what exactly are you trying to alter, and who are you trying to fool, joe public or somebody who knows what he's doing?
 
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Pat MacInnes
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#4
I know that by copying the image once you've opened the raw into PS, and then pasting it into a new document, you get rid of exif data (this works to fool HDR software) but I'm not sure about raw.
 
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Ed
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#5
hi all

quick question that i can't seem to find the answer to........

is it possible to edit (photoshop) a raw file without anyone being able to detect that it was tampered with?

any help/advice much appreciated

d.
Software the forensics people use can detect any changes you make to a RAW file or jpeg.
 
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wayne clarke
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#6
You can edit the raw in camera raw then open it in photoshop, then re-edit the raw back to it's default appearence (leaving you with an edited version) and the raw "looking" original but as said real experts could tell you have opened it and worked on it. But it would be easier to just make a copy of the raw for yourself.
 
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nowler
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#7
thanks for the replies folks

it's just a theoretical exercise as far as i know, a colleague at work asked me if it could be done, i reckoned anything is possible but didn't know for sure....

it was something to do with a competition she was entering where the entries had to be either film, slides or raw images as they reckoned they couldn't be tampered with......

cheers

d.
 
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#8
Forgive me if I'm being thick, but you can't view a raw file without doing something to it can you?
Depending on which software you use, what you see on screen will differ from one application to the next and some software just displays the embedded jpeg as a preview.

What that means, if I'm thinking about this right, is that you friend might be looking at their pic in DPP for example and be happy, submit the raw file and the judges look at it in Photoshop raw converter, the image could look quite different.
 
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Sean
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#9
thanks for the replies folks

it's just a theoretical exercise as far as i know, a colleague at work asked me if it could be done, i reckoned anything is possible but didn't know for sure....

it was something to do with a competition she was entering where the entries had to be either film, slides or raw images as they reckoned they couldn't be tampered with......

cheers

d.
Ah, all this elitist nonsense really annoys me. Nevermind.

I think that there is most likely a way and the judges would not be able to tell, but whether it's worth it or not is a different matter.
 
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#10
They're probably trying to address the potential for excessive photoshop being used on digital images, and they would request the RAW's for reference.
I suspect there would be a degree of acceptable retouching, but the RAW / Film / Slide is there to provide the reference.

Otherwise they end up with things like this

http://photoshopdisasters.blogspot.com/2008/12/national-geographic-heres-your-prize.html

http://theonlinephotographer.typepa...alist-accused-of-excessive-photoshopping.html

http://www.pdnpulse.com/2009/04/photo-contest-wades-into-murky-waters-of-digital-mainpulation.html
 
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nowler
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#12
good replies guys, but i think i maybe didn't make it completely clear,

it's not a photography competition, the photos are used as a means to display the mertis of other work, which could be photoshoped to enhance someones entries if that makes sense. the actual actual quality of the photograph is neither here nor there.......

knowing her well, i'd say she's not trying to play the system, she was just curious as to whether other entrants could stack the deck so to speak!

i'm not sure how serious it is all taken, or to what extent they'd check the raw's for being tampered with.

i'd have thought it would be possible with some application or other that must allow you to edit the exif data without being noticed???? or allow you to edit without altering anything other than the pixles you've changed or touched up???

who knows.

cheers so far anyway

d.
 

mmcp42

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Mike
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#13
usually find that once you start to "tinker" the histogram stops being smooth and starts to have great gaps in it
always a giveaway!
 
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Andy Jones
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#15
As I said above, it's perfectly possible to write a bit of code that will turn any image into a raw file - after all your camera does it every time you press the shutter ;)
 

Arkady

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#16
One of the factors with RAW files was the ability to see if they'd been tampered with - this is mostly as a result of Police and Law Enforcement agencies wanting a way of preserving the chain of evidence with forensic and surveillance imagery...
It took a lot of convincing by camera manufacturers and digital imagery experts to allow Courts to admit digital imagery as evidence. That's the main reason that RAW files remain sacrosanct.
We (the MoD) asked Nikon at the outset of the digital-age if this was possible and told them that until they achieved this we would not use their digital cameras for the majority of surveillance and non-PR work...they and other manufacturers stepped up and that is one of the reasons why RAW files cannot be tampered with without leaving traces.
 
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#17
One of the factors with RAW files was the ability to see if they'd been tampered with - this is mostly as a result of Police and Law Enforcement agencies wanting a way of preserving the chain of evidence with forensic and surveillance imagery...
Hmm,

So this leaves a couple of possibilities then.
Either
a) there is a signed component to the raw image. This could, if you could be bothered, be unlocked from the running firmware, and used to re-code the signing at the end of the file after modification

b) if there were a signed component, then you could instead probably manipulate the sensor memory to contain the information you wanted, then use the camera to re-code the image

these two would be undetectable. But not a 5 minute job.

c) You could modify the encoded file, reset the CRC and not worry about the signed component, (if it exists, I'll take one apart tonight). It would get past a judge, the image /itself/ could get past a forensics expert, but the data-code wouldn't
 

Arkady

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Rob
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#18
Hmm,

So this leaves a couple of possibilities then.
Either
a) there is a signed component to the raw image. This could, if you could be bothered, be unlocked from the running firmware, and used to re-code the signing at the end of the file after modification

b) if there were a signed component, then you could instead probably manipulate the sensor memory to contain the information you wanted, then use the camera to re-code the image

these two would be undetectable. But not a 5 minute job.

c) You could modify the encoded file, reset the CRC and not worry about the signed component, (if it exists, I'll take one apart tonight). It would get past a judge, the image /itself/ could get past a forensics expert, but the data-code wouldn't
We (the MoD, the US DoD, Customs and Immigration, the various UK, US Federal, State and European Police and Law-Enforcement Authorities) have been informed by the camera manufacturers that any manipulation such as you describe would be detectable.
That is good enough for digital imagery to be included as evidence at trial in the UK, USA and European Courts.
 
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wayne clarke
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#19
We (the MoD, the US DoD, Customs and Immigration, the various UK, US Federal, State and European Police and Law-Enforcement Authorities) have been informed by the camera manufacturers that any manipulation such as you describe would be detectable.
That is good enough for digital imagery to be included as evidence at trial in the UK, USA and European Courts.
I suspect that an expert who knows and understands the working of the files and code, and with reasonable resources could probably fool them. Lets not forget Canon/Nikon (whoever) are very unlightly to examine files used in court case, in reality they would only be called in cases where tampering was suspected in the first place.
 

PauloWanClift

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#20
One of the factors with RAW files was the ability to see if they'd been tampered with - this is mostly as a result of Police and Law Enforcement agencies wanting a way of preserving the chain of evidence with forensic and surveillance imagery...
It took a lot of convincing by camera manufacturers and digital imagery experts to allow Courts to admit digital imagery as evidence. That's the main reason that RAW files remain sacrosanct.
We (the MoD) asked Nikon at the outset of the digital-age if this was possible and told them that until they achieved this we would not use their digital cameras for the majority of surveillance and non-PR work...they and other manufacturers stepped up and that is one of the reasons why RAW files cannot be tampered with without leaving traces.
This is interesting to me at the moment, the police have just taken a few of my images away in jpg format as evidence in a very serious case involving my girlfriend, I may have to give the officers dealing with the case a ring and mention this as they don't seem to know too much about image files, if I can supply them the nef's then they can prove they have not been tampered with. (y)
 
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#21
This is interesting to me at the moment, the police have just taken a few of my images away in jpg format as evidence in a very serious case involving my girlfriend, I may have to give the officers dealing with the case a ring and mention this as they don't seem to know too much about image files, if I can supply them the nef's then they can prove they have not been tampered with. (y)
Arkady is probably mentioning the Original Security Data implementations on the camera. These sign the images with a pre-determined key signature, in the same way that SSH encryption works.
Once the image is created, it is impossible to modify the image, without already having the private key. However, if you modify the image before the private key is put in, then the data can be modified, and re-coded.

Simply put, if you really wanted to, you could modify the sensor on the camera in order to re-play an image to the encoding program. It isn't easy, and to be honest, not worth the hassle.

Also, although the image itself would be indestinguishable from one which had been taken properly, an investigation of the camera itself (which if a court was concerned, they could easily request), would show that the modification had taken place.

As for your girlfriend...
It is unlikely that you will have already have put a coded key on your camera (I think you have to pay the manufacturers for a license anyway). So there is not too much benefit in sending them the raw. Keep it, they may ask for it later, but it is probably not storing the data required.

As for the OP's original intent. Changing the data in a raw picture, without the signed data, is possible. Assuming that it is not possible to fake a raw is wrong. A raw can relatively be changed, but would be noticed with a decent look. A more in-depth modification can be made which would make a more detailed investigation necessary. If you go the full hog, and look at evidence level confidence, then modification at the software and hardware level would be required.
 
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