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Old 07-11-2013   #11
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Default Re: How to remove Exif Data from RAW?

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Originally Posted by BambersImages View Post
Why do you want to strip exif data from raw files?
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Originally Posted by Steven G Webb View Post
I see this thread originated in 2010. Is or was there a purpose in removing the EXIF data from the RAW file?
This is the as yet unanswered question:

WHY ??
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Old 07-11-2013   #12
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Default Re: How to remove Exif Data from RAW?

I saw a few people interjecting the opinion that it was not a good thing to do (removing the EXIF from the RAW) but did so without knowing a purpose in the OP's mind. Maybe there is something here to be learned by more than one of us.
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Old 07-11-2013   #13
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Default Re: How to remove Exif Data from RAW?

There are times where one might be req'd to submit a RAW file because the RAW data is required for:
- Scientific work
- Recovery of fragile end-point data
- Testing of a RAW editing software
I have been in that situation once and for purposes of proof of ownership, have used a hex editor to remove the serial number of my camera from the metadata block and inserted additional traceability information which could only be decoded or extracted with another special s/w program. I can think of a number of other possible reasons to strip EXIF data some of which may not be well intentioned.
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Old 07-12-2013   #14
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Default Re: How to remove Exif Data from RAW?

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Originally Posted by mistermonday View Post
There are times where one might be req'd to submit a RAW file because the RAW data is required for:
- Scientific work
- Recovery of fragile end-point data
- Testing of a RAW editing software
Those are certainly valid uses of RAW files, but I don't recalll anyone questioning that RAW files are useful?
Quote:
I have been in that situation once and for purposes of proof of ownership, have used a hex editor to remove the serial number of my camera from the metadata block and inserted additional traceability information which could only be decoded or extracted with another special s/w program.
Granted that that can be accomplished in exactly that way... but 1) that is not the same as removing all Exif data and 2) that is a difficult and awkward way to accomplish something that is reasonably simple.

I see no value at all in removing the camera serial number, but do see that as counter productive to proving ownership. As for inserting encrypted traceable information that method is not truly effective because the sensor data can be extracted and then inserted into a new RAW file that is built totally independent of the original. The only methods that have any significant integrity necessarily must embed coded information into the sensor data itself.

To perform something just as useful as the above, with the same weaknesses, requires only that an encrypted message be placed into one of the several possible text fields, or into one of several possible binary fields, both of which can be done with software such as exiftool. Another, and perhaps less obvious way, would be to encode the message into the embedded JPEG image.

The point is that use of a hex editor is unreasonably difficult and unnecessary given that it produces nothing of extra benefit.
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I can think of a number of other possible reasons to strip EXIF data some of which may not be well intentioned.
I can't think of any reason that is well intentioned in regard to a RAW file.
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Old 07-12-2013   #15
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Default Re: How to remove Exif Data from RAW?

It take me less than a minute to do what I need to do with a hex editor. However, you can strip out the entire Metadata block with one command in ExifTool.
As for your statement about intentions, your scope of reasons seems a bit limited.
Some photographers sell their photos but value their privacy while others believe in selling what they capture but not how they capture it. A photographer may not want his client to know the conditions under which the photos were taken, or what model camera and lens he used or what the elapsed time was between the 1st and last photo of a job. He may not wish to expose the depth of field used or what exposure time was required to obtain a motion blur, or how he skillfully used rear curtain sync. Cameras record a lot of data whose intellectual property value is worth more than a simple time and date stamp. Protecting or withholding that information should not be interpreted as malintention.
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I can't think of any reason that is well intentioned in regard to a RAW file.
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Old 07-13-2013   #16
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Default Re: How to remove Exif Data from RAW?

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It take me less than a minute to do what I need to do with a hex editor. However, you can strip out the entire Metadata block with one command in ExifTool.
And how long, with a hex editor, does it take to figure out exactly where any given data field is located? In particular if it is a field with an unknown numerical value...

Using exiftool to remove a single entry merely requires knowing the name of the entry to be deleted.

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As for your statement about intentions, your scope of reasons seems a bit limited.
Or more likely a bit more experienced...
Quote:
Some photographers sell their photos but value their privacy while others believe in selling what they capture but not how they capture it. A photographer may not want his client to know the conditions under which the photos were taken, or what model camera and lens he used or what the elapsed time was between the 1st and last photo of a job.
So explain just exactly why anyone who doesn't want the model of camera to be known is going to distribute a RAW file? That simpy is not possible! The raw sensor data is useless unless the camera model is known.

As I pointed out to start with, removing metadata from a RAW file is not reasonable and virtually any argument to suggest it is will instead be an argument to not provide the RAW file in the first place.

This is not and never has been a discussion of removing metadata from image files, it is about removing metadata from files containing raw sensor data. The distinction is huge.

Quote:
Protecting or withholding that information should not be interpreted as malintention.
But that protection starts with not distributing raw sensor data...

We are NOT talking about removing metadata from an image file!
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Old 07-13-2013   #17
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Default Re: How to remove Exif Data from RAW?

I see that Haring has not been back to comment. I still think the question on why would you want to strip exif data from a raw file is valid. Why would you distribute a raw file rather than a tif or jpg...especially if it was stripped?
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Old 07-13-2013   #18
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Default Re: How to remove Exif Data from RAW?

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Originally Posted by BambersImages View Post
I see that Haring has not been back to comment. I still think the question on why would you want to strip exif data from a raw file is valid. Why would you distribute a raw file rather than a tif or jpg...especially if it was stripped?
I believe the list by mistermonday was reasonable for why raw sensor data might be shared. To that list I would specifically add it is required for any kind of camera/sensor evaluation work.

But there don't seem to be any valid reasons to strip Exif data if it is valid to share the raw sensor data.

As you are implying, if there is a reason to strip Exif data there is more reason to use an image format rather than send raw data. (I thought the idea that hiding which camera produced the raw sensor data was particularly indicative of how unaware these comments have been, given that absent knowledge of which camera produced the data it might as well be encrypted so well that even the NSA can't use it!)
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Old 07-13-2013   #19
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Default Re: How to remove Exif Data from RAW?

Please see inserted text

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Originally Posted by apaflo View Post
And how long, with a hex editor, does it take to figure out exactly where any given data field is located? In particular if it is a field with an unknown numerical value...

There are some very powerful hex editors and as I indicated, in my case only a small edit was required and I knew exactly the content of the fields I was searching for.

Using exiftool to remove a single entry merely requires knowing the name of the entry to be deleted.

I have no argument that Exiftool is likely the best tool to use for someone trying to erase all Exif data

Or more likely a bit more experienced...

So explain just exactly why anyone who doesn't want the model of camera to be known is going to distribute a RAW file? That simpy is not possible! The raw sensor data is useless unless the camera model is known.

Not so. I was opening and processing RAW NEF files from Nikon D800 and D600 files long before Photoshop and other image editors had implemented updates to read those files. There were many RAW processing programs which use DCRAW to extract the sensor data. All they require is the tag for that data. The camera model is not required. In fact these applications using DCRAW extract the entire image array which produces an image of dimensions which are larger than those published by the camera manufacturer and larger that those produced by PS / ACR because those crop the perimeter of the array.


As I pointed out to start with, removing metadata from a RAW file is not reasonable and virtually any argument to suggest it is will instead be an argument to not provide the RAW file in the first place.

This is not and never has been a discussion of removing metadata from image files, it is about removing metadata from files containing raw sensor data. The distinction is huge.

But that protection starts with not distributing raw sensor data...

We are NOT talking about removing metadata from an image file!
This conversation has been going off on tangents of technical minutia so let me try to put it back on track. The two primary questions in this thread are: Can Exif data be removed form a RAW file and what legitimate reason would you have to do that.

I think we agree that it can be done and Exiftool is one efficient tool to use.
I gave you a list of of what I thought were legitimate reasons and but you completely ignored them. I will jump ahead and answer the same question for Bambers below.

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Originally Posted by BambersImages View Post
I see that Haring has not been back to comment. I still think the question on why would you want to strip exif data from a raw file is valid. Why would you distribute a raw file rather than a tif or jpg...especially if it was stripped?
Clare, there are probably a whole bunch of reasons similar to the ones I have listed and another I will list here. And indeed Haring may have a totally different one.
Here is another real world example. If you are heavily involved with HDR imaging you know that often having RAW files is critical to certain tasks. Any processing of a RAW file into a jpg or tiff involves demosaicing, interpreting, and mapping of a block data into a color space. During that process the clipping of endpoint data is inevitable. Almost every week, a bracketed set of RAW files is shared on the HDR forum. Not everyone who is prepared to make their files available for public use wishes to forgo their complete copyright ownership. Not everyone wish to have all of the Exif data exposed. Not everyone wishes to offend very religious people by revealing that they were out working on Sunday morning instead of being in Church. OK that last one is a bit over the edge but there are a lot of reasons.
Is there a possibility that the intent of stripping metadata is image theft or some other malintention? Yes that is always possible. However I see no reason to be judgemental or paranoid when a question like the one posed in the OP comes up. It was a simple straight forward question about a s/w solution. If we think there is some devious and unlawful underlying purpose we should just pass over the thread and move on to the next one. If everyone feels the same way then the question will go unanswered and the OP will also move on.
Phil Harvey, a brilliant individual well respected in his field went to great trouble to create Exiftool and make it available for free. Clearly he also sees many legitimate uses for his creation.
If Haring chooses to infuse any additional information that's great. Otherwise I see no value in continuing additional discussion here.
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Old 07-13-2013   #20
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Default Re: How to remove Exif Data from RAW?

Quote:
Originally Posted by mistermonday View Post
Not so. I was opening and processing RAW NEF files from Nikon D800 and D600 files long before Photoshop and other image editors had implemented updates to read those files. There were many RAW processing programs which use DCRAW to extract the sensor data. All they require is the tag for that data. The camera model is not required.
I've mucked around with the source code to DCRAW long enough to know exactly how it requires the make and model of camera. (I've previously modified it immediately after several different Nikon models were announce so as to be able to interpolate the first RAW files made available on the Internet.)

If you look at the source code you'll find that which make of camera it is is in fact absolutely essential, and which specific model is necessary to correctly (as opposed to something close) adjust the interpolation algorithm. For example, the current source code has these lines, which very clearly indicate that the specific model is significant::


{ "NIKON D800", 0, 0,
{ 7866,-2108,-555,-4869,12483,2681,-1176,2069,7501 } },

...

{ "Nikon D600", 0, 0x3e07,
{ 8178,-2245,-609,-4857,12394,2776,-1207,2086,7298 } },

...
} else if (!strcmp(model,"D3200") ||
!strcmp(model,"D600") ||
!strncmp(model,"D800",4)) {
width -= 46;
} else if (!strcmp(model,"D4")) {
width -= 52;
left_margin = 2;
} else if (!strncmp(model,"D40",3) ||
!strncmp(model,"D50",3) ||
!strncmp(model,"D70",3)) {
width--;
}

It gets far worse than that however, because if everything except the sensor data is removed there is no way to determine what type of Bayer Filter is used, how to adjust the colors, or even what the actual size of the useful data set is! Technially that is not Exif data, and instead is in the MakerNotes, but it is essential metadata.

Quote:
In fact these applications using DCRAW extract the entire image array which produces an image of dimensions which are larger than those published by the camera manufacturer and larger that those produced by PS / ACR because those crop the perimeter of the array.
True, but that is irrelevant to this discussion. It is also true the Nikon's software produces an image that is smaller than what DCRAW produces. (It's also very much open to debate as to whether that is or not a detrimental factor in the interpolation algorithm used by DCRAW! But that's a totally different discussion topic.)

Quote:
This conversation has been going off on tangents of technical minutia so let me try to put it back on track. The two primary questions in this thread are: Can Exif data be removed form a RAW file and what legitimate reason would you have to do that.

I think we agree that it can be done and Exiftool is one efficient tool to use.
I gave you a list of of what I thought were legitimate reasons and but you completely ignored them. I will jump ahead and answer the same question for Bambers below.
An unimportant point, but I hardly ignored your list! I have commented on it's validity twice.

Quote:
Clare, there are probably a whole bunch of reasons similar to the ones I have listed and another I will list here. And indeed Haring may have a totally different one.
Here is another real world example. If you are heavily involved with HDR imaging you know that often having RAW files is critical to certain tasks. Any processing of a RAW file into a jpg or tiff involves demosaicing, interpreting, and mapping of a block data into a color space. During that process the clipping of endpoint data is inevitable. Almost every week, a bracketed set of RAW files is shared on the HDR forum. Not everyone who is prepared to make their files available for public use wishes to forgo their complete copyright ownership.
Sharing the files here has zero effect on "their complete copyright ownership", and in no way cause anyone to "forgo" said copyright.

Quote:
Not everyone wish to have all of the Exif data exposed.
I'm not entirely convinced that is necessary, but granted that this is the closest that anyone has come to a valid reason to remove Exif data from a RAW file.

Quote:
Not everyone wishes to offend very religious people by revealing that they were out working on Sunday morning instead of being in Church. OK that last one is a bit over the edge but there are a lot of reasons.
Is there a possibility that the intent of stripping metadata is image theft or some other malintention? Yes that is always possible. However I see no reason to be judgemental or paranoid when a question like the one posed in the OP comes up. It was a simple straight forward question about a s/w solution. If we think there is some devious and unlawful underlying purpose we should just pass over the thread and move on to the next one. If everyone feels the same way then the question will go unanswered and the OP will also move on.
All totally non-relevant to the question/discussion. Whether there are valid reasons which have bad intent is not the question. The question is whether any valid reason to strip Exif exist for good purposes.

Quote:
Phil Harvey, a brilliant individual well respected in his field went to great trouble to create Exiftool and make it available for free. Clearly he also sees many legitimate uses for his creation.
If Haring chooses to infuse any additional information that's great. Otherwise I see no value in continuing additional discussion here.
More irrelevant discussion (though granted it is interesting).

Given your observation about tangents of technical minutia, which in fact are significant, I can't see the specific reason for so many comments about totally non-relevant, even if interesting, topics.


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