Problems altering CR2 metadata on OS X

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Posted on Thu Dec 22 13:56:48 2005 by msbc

I recently added some EXIF data to some Canon 20D CR2 files. I was using a Contax lens on the camera so no lens or aperture info was recorded. I added this data with exiftool 5.85 on OS X 10.4.3. The resulting files display a black thumbnail preview in the Finder and show a black image in both Preview and Aperture 1.0.1. Seems there is an incompatibility with exiftool written metadata and OS X?

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Posted on Thu Dec 22 14:06:39 2005 by minimal in response to 1501

Re: Problems altering CR2 metadata on OS X

Interesting - when I was hacking up the Raw.plist file to make 10.4.4 support the 350D I found that adding data would cause the OS X image to turn black (in particular I was trying to see if adding an entry that the Digital Rebel XT had that the 350D didn't helped the colour cast I got). This lead me to think that Apple are using position dependant decoding of the data structure rather than parsing the file 'properly', but I have no hard evidence for this. All of the files I altered with ExifTool viewed without a problem in Canon's DPP software and when decoded by dcraw, so the modifications are not themselves incorrect.

If you can change existing data but not add new items, then I think it's time for a bug submission to Apple as they have obviously only just started messing with RAW and have a lot of catching up to do (not that I'm still sulking about the lack of non-US camera support. That would be petty).

HTH,
--
ian.

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Posted on Thu Dec 22 15:49:16 2005 by exiftool in response to 1502

Re: Problems altering CR2 metadata on OS X

I just became aware of this yesterday. This problem was reported (by our Ian?) in an Apple Discussions thread from Nov 1.

My conclusion is the same as Ian's. I'm still running Panther so I don't have an opportunity to test this out myself, but my guess is that Apple is not properly decoding the raw images. It is likely that they are getting the white balance values from a fixed offset within the maker notes, and this offset will change when the image is edited (even if nothing new is added).

If this is true, then the OSX preview could also be broken by something as simple as a firmware upgrade to your camera. Hopefully Apple will fix this.

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Posted on Thu Dec 22 16:00:59 2005 by minimal in response to 1503

Re: Problems altering CR2 metadata on OS X

Yup, that's me: I also got a typo in my post above - I am still using 10.4.3 and not 10.4.4 as I previously said. There is some hope that rather than just fix the 350D issue with more hacks, the soon-to-be-forthcoming 10.4.4 will have a full file format parser instead.

I haven't got an early developer account, though, so I'll need to wait until the expected release towards the end of this year.

HTH,
--
ian.

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Posted on Thu Dec 22 17:51:54 2005 by exiftool in response to 1504

Re: Problems altering CR2 metadata on OS X

I have just confirmed that ExifTool-edited 350D CR2 images work fine with Canon Digital Photo Professional, Photoshop CS2 and dcraw. This definitely looks like an Apple bug.

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Posted on Wed Jan 4 19:36:42 2006 by minimal in response to 1503

Re: Problems altering CR2 metadata on OS X

And as if by magic, more evidence that points towards position-based decoding of RAW files:

http://www.luminous-landscape.com/reviews/software/aperture-none.shtml

In particular this paragraph:

"For example, I currently use a Canon 1Ds MKII, a Canon 5D and a Phase One P25 medium format back. Only the MKII is supported, but I found that files shot since I updated the camera's firmware in late November '05 are not."

Here's hoping that 10.4.4 will have true RAW parsing: if Apple forces an upgrade to 10.5 for this they're going to loose a lot of friends...

--
ian

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Posted on Thu Jan 12 16:32:41 2006 by exiftool in response to 1569

Re: Problems altering CR2 metadata on OS X

Good article. Thanks for pointing it out.

OS X 10.4.4 came out a couple of days ago... did it fix the problem? (fingers crossed)

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Posted on Thu Jan 12 16:45:21 2006 by minimal in response to 1617

Re: Problems altering CR2 metadata on OS X

Yes and no - 10.4.4 correctly reads both European (verified by me) and Japanese (verified by a poster on my blog) 350D RAW files, but playing with IPTC tags makes 10.4.4 render the image as pure black :( I haven't tried to test the quality of the image conversion itself: the inability to add tags has made me ignore OS X as a valid base for RAW decoding and look at non-native alternatives.

I've put up a quick note about it, but have been spending most of my time messing around with Adobe's Lightroom Beta 1, which doesn't do much with IPTC at the moment, but I shall test each time they release a new version.

If Apple do stick with this decoding method, then I really hope they decouple the RAW update from the O/S minor release version.

HTH,
--
ian.

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Posted on Thu Jan 12 18:23:28 2006 by exiftool in response to 1618

Re: Problems altering CR2 metadata on OS X

Thanks for the update. Pity that the problem didn't get fixed though. It is good that Lightroom doesn't have the same problem, although this is predictable because it may use the same decoding routines as Photoshop.

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