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Author Topic: 34_DNG  (Read 12326 times)
Ronny Nilsen
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« on: October 04, 2012, 04:42:50 AM »
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In video 34_DNG there is mentioned that we now have more than 280 different propitiatory raw file formats, because Adobe have to reverse engineer the file format for every new camera. I can understand that, but that doesn't mean that the file format as such always is different, just that Adobe don't know the whole truth of the file format.

Just for fun i put the CF-card from my new Canon 5D MkIII into an old Canon M80 hard drive with a display (used to back up images in the filed in the old days), and it happily showed all the images. The colors even looked OK. So when a 6 year old device can render CR2 raw-files from a new camera, I suspect that CR2 might be some sort of propitiatory format that is common among all Canon cameras that use the CR2, not one format pr. camera.

What is really going on here? I can see that a new profile is needed for a new camera in LR, but that is not the same as a different file-format. Why can old Canon cameras and devices display raw-files from new cameras made many years afterwards?

Ronny
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Tony Jay
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« Reply #1 on: October 04, 2012, 04:56:33 AM »
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Without serious qualification I don't think you have made your point.

Regards

Tony Jay
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Ronny Nilsen
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« Reply #2 on: October 04, 2012, 05:16:46 AM »
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I'm not trying to make point, I'm trying to understand the nature of the raw-files. Do Canon change the file-format CR2, or is it a more or less stable propitiatory format? Both is bad, but the last option is less bad.  Smiley

Ronny
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Tony Jay
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« Reply #3 on: October 04, 2012, 05:20:15 AM »
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Ronny , the fact that you could view CR2 files from a late model camera on hardware that is 6 years old is meaningless - it all depends on the software that you are using.
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Ronny Nilsen
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« Reply #4 on: October 04, 2012, 06:00:58 AM »
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But the software on that device is also 6 years old, I have never bother to update the firmware on the M80 (and it's not sold any more).

As far as I can see there is 2 possible explanations:
  • The propitiatory CR2 format is changed for each camera, but it contains a high resolution jpeg that is used by old devices.
  • The propitiatory CR2 format is stable, so if you know the secret you can read files from new cameras.

The 6 year old M80 (or software/firmware) was happily telling me that the images was shot with a Canon 5DMkIII and letting me zoom in on the image to see the details. It was slow, but working.

Ronny
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Tony Jay
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« Reply #5 on: October 04, 2012, 06:04:19 AM »
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Well Ronny, forgive me for splitting hairs but that was why I was querying your statement.
At least now I can actually understand the point - and it is interesting.

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Tony Jay
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Fips
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« Reply #6 on: October 04, 2012, 06:53:16 AM »
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Here's my more or less educated guess: You old device reads just a jpp preview image embedded in the raw file. Therefore it doesn't need to know anything about the raw data and the technical details. The fact that the image displays just shows that the file structure seems to be the same as six years ago.
Actually that is in accordance with what Eric explained in some other thread on this forum. Most raw format are very similar to the tiff standard and if your old Canon drive basically just interprets raw files as tiffs then it is not so surprising that it can handle the most recent files too. At least the ones from Canon.

Updating a raw converter however is much more complicated as you have to figure out all the details like white balance data, proper demosaicing according to the strength of the AA filter, possibly lens correction data, and so on.
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elied
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« Reply #7 on: October 04, 2012, 07:23:03 AM »
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There is another possibility that you have failed to consider and I think it is the right one; that your M80 is displaying the embedded jpg within the CR2, which can be accessed and displayed in the same way in any CR2 although other aspects of the Raw file are different. I also have old software (Breeze Browser Pro) that displays 5D2 and 5D3 CR2 files and I know for a fact that it is merely showing the embedded jpgs and is incapable of performing a conversion. From displaying a ready-made jpg to doing an actual Raw to RGB conversion is a long distance.

Moreover, Canon itself issues a new version of its own converter, DPP, with every new model release - undoubtably an expense that they would prefer to avoid (thus increasing profits) if only they could.
« Last Edit: October 04, 2012, 07:24:45 AM by elied » Logged

Roll over Ed Weston,
Tell Ansel Adams the news
Ronny Nilsen
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« Reply #8 on: October 04, 2012, 07:29:51 AM »
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Updating a raw converter however is much more complicated as you have to figure out all the details like white balance data, proper demosaicing according to the strength of the AA filter, possibly lens correction data, and so on.

I agree that this must be done, but that is profiling or configuration of interpretations of the data in the file, and would not necessarily mean that the file format (where and what the data looks like) has changed in any way.

It would be the same with DNG, there we know that the file format is stable, but for a new camera with DNG it would still be necessary to "figure out all the details like white balance data, proper demosaicing according to the strength of the AA filter, possibly lens correction data, and so on" to get an optimal rendering of the image.

Ronny
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Fips
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« Reply #9 on: October 04, 2012, 07:44:00 AM »
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Yes, but we don't really KNOW when and what changes in Canon's file format. It just SEEMS to be stable. With DNG you do know the exact file format and it's well documented. If you are developing any kind of software that needs to handle raw data that is already a pretty big advantage. And we were just talking about Canon here. There are many other manufacturers with their own more or less stable formats which make the whole thing a mess.
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ErikKaffehr
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« Reply #10 on: October 06, 2012, 02:32:33 PM »
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Hi,

The device probably does not render the image just displays an embedded JPEG.

My experience have been more to the contrary. My devices just stopped to render anything.

Best regards
Erik



In video 34_DNG there is mentioned that we now have more than 280 different propitiatory raw file formats, because Adobe have to reverse engineer the file format for every new camera. I can understand that, but that doesn't mean that the file format as such always is different, just that Adobe don't know the whole truth of the file format.

Just for fun i put the CF-card from my new Canon 5D MkIII into an old Canon M80 hard drive with a display (used to back up images in the filed in the old days), and it happily showed all the images. The colors even looked OK. So when a 6 year old device can render CR2 raw-files from a new camera, I suspect that CR2 might be some sort of propitiatory format that is common among all Canon cameras that use the CR2, not one format pr. camera.

What is really going on here? I can see that a new profile is needed for a new camera in LR, but that is not the same as a different file-format. Why can old Canon cameras and devices display raw-files from new cameras made many years afterwards?

Ronny
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