How to remove Exif Data from RAW files?

Peano wrote in post #11341278
I think the bottom line is: You cannot alter the exif data in a raw file.

Peano wrote in post #11341839
Why he wants to do it is irrelevant. Don't confuse the possibility of doing something with the motive for doing it. The OP asked whether it is possible. His motive has no relevance to the question of whether it can be done.

Is it possible to strip the exif data from a jpeg? Sure, and I can show you how without knowing why someone might want to do it.

John the Geek wrote in post #11341871
I ask why because I already know editing EXIF data in RAW files can be done. (I just did it above you there.) What I don't know yet is why and what he wants to change. If I know that info I could get more specific about how he could go about doing it.

Peono, I'm not sure why but you seem to be picking arguments here with some of us but I don't see anything to argue about. We actually can put forth a couple ways to at least alter the exif, and make it meaningless, but because the OP has been absent without giving us any information of what he is trying to accomplish none of us knows if we are answering his question helpfully or not, but we are certainly trying and at the same time asking him for enough info that could enable us to answer him. But you seem to be picking at a lot of what we are saying in that attempt, and I'm not sure why...

I just tried using exiftool with the -all= option on a 30D CR2 file and it deleted a large amount of the EXIF information before hitting an error (Can't delete IFD0 from CR2) and stopping.

After that I had to delete fields individually by name, in the end only the following remained as read only:

---- IFD0 ----
PreviewImageStart               : 7324412
PreviewImageLength              : 0
---- IFD1 ----
ThumbnailOffset               : 190
ThumbnailLength               : 7212
---- IFD3 ----
StripOffsets               : 7402
StripByteCounts               : 7022097
RawImageSegmentation            : 1 1798 1798
---- Composite ----
ThumbnailImage               : (Binary data 7212 bytes, use -b option to extract)

John the Geek wrote in post #11341814
I have a super-secret RAW file for you. It was shot with a Canon 3D prototype with a new 2000mm f/0.8 USM III lens. Check the EXIF, it's all there in the RAW.

IMG_7679.CR2

So, I was able to open your file in DPP, no problem, and view the exif, no problem. I see you only changed the camera model and the lens model. I was also able to convert and save and view the jpeg, no problem.

Now my question: what did you use to edit the Raw? I guess from a later post that ExifTool could do that -- is that what you used, or a Hex editor, text, or ??

Like we see below there is only so far you can go, but maybe farther than one might think.

Also, if using a Hex or text editor, wouldn't one need to ensure that the file byte count was being updated with the edits?

tonylong wrote in post #11344169
So, I was able to open your file in DPP, no problem, and view the exif, no problem. I see you only changed the camera model and the lens model. I was also able to convert and save and view the jpeg, no problem.

Now my question: what did you use to edit the Raw? I guess from a later post that ExifTool could do that -- is that what you used, or a Hex editor, text, or ??

Like we see below there is only so far you can go, but maybe farther than one might think.

Also, if using a Hex or text editor, wouldn't one need to ensure that the file byte count was being updated with the edits?

I used a hex editor (Hex Fiend for Mac, specifically) Most hex editors show you the ASCII representation of each byte, allowing you to modify them one byte at a time. For my example, since each character is only 1 byte, I simply swapped char for char. In the case of the lens, where the replacement data was longer, I replaced some of the 00 bytes at the end of the string with the characters I needed.

In all practicality, an application designed to read the EXIF data from the CR2, and then write it back out would be best, since (like you pointed out) you can only get so far flipping bytes before you introduce byte-range issues.

Of course it can be done, forget about the moon - we can now alter the gender of human beings and not to mention whip up things like "content aware fill".

Although I agree with what Tim says (and I find myself usually in agreement with what he says), someone else could have a different point of view. So I think John is right in asking 'what' but the 'why' is probably not as important here. The OP might not wanna humor us with that information, maybe it's an elaborate tax evasion scheme, maybe he just want to give the Canonrumors guy a hoax, it's not really important.

lowcrust wrote in post #11347655
Although I agree with what Tim says (and I find myself usually in agreement with what he says)

Maybe you should see someone about that...

I'm looking to modify EXIF data for adapted lenses. It would make my life much easier to have the real lens represented rather than the nifty-fifty for every file. I prefer to be able to do this in Lightroom but that is not likely (is it?) so I checked into ExifTool which will do the job but I have one question. I thought the following functional feature was interesting.

Decodes a riddle wrapped in a mystery inside an enigma

That sounds like an interesting feature to code. I am assuming that this is a real entity?

jetcode wrote in post #11434613
I thought the following functional feature was interesting.

Decodes a riddle wrapped in a mystery inside an enigma

That sounds like an interesting feature to code. I am assuming that this is a real entity?

No, that's just the humor of a successful, yet frustrated, programmer.

The fact that some EXIF entries are nested, and then sub-nested, and sometimes sub-nested below that, introduces quite a headache to a programmer who has to follow the (il)logic to it's end. I've written an EXIF reader into my web site using PHP and thankfully a lot of work (suffering and bleeding) was already done for me so it's only mildly frustrating to me instead of a migraine.

Protocols ... I can relate. What would suggest for a fast way to change lens focal and aperture data in the metadata section since it doesn't look like Lightroom supports that? It would be neat to capture the lens information without having to enter it in a comment field.

So far I haven't found anything. I guess it is not possible.
Is there a specific software?

Try EXIFTools. Not sure if it will do it or not.

John the Geek wrote in post #11341814
I have a super-secret RAW file for you. It was shot with a Canon 3D prototype with a new 2000mm f/0.8 USM III lens.

Do you realize how big that lens would be...