Aperture DNG support.

Sadly you are missing one important fact: something at some point has to translate proprietary RAW into linear DNG. It would be ideal if the camera manufacturers did that "in camera" but since they do not, the application must.

The challenge is the following process ....


Mapping Raw Values to Linear Reference Values

The section describes DNG's processing model for mapping stored raw sensor values into linear reference values. Linear reference values encode zero light as 0.0, and the maximum useful value (limited by either sensor saturation or analog to digital converter clipping) as 1.0.
If SamplesPerPixel is greater than one, each sample plane should be processed independently.
The processing model follows these steps:
• Linearization
• Black Subtraction
• Rescaling
• Clipping
Linearization
The first step is to process the raw values through the look-up table specified by the LinearizationTable tag, if any. If the raw value is greater than the size of the table, it is mapped to the last entry of the table.
Black Subtraction
The black level for each pixel is then computed and subtracted. The black level for each pixel is the sum of the black levels specified by the BlackLevel, BlackLevelDeltaH and BlackLevelDeltaV tags.
Rescaling
The black subtracted values are then rescaled to map them to a logical 0.0 to 1.0 range. The scale factor is the inverse of the difference between the value specified in the WhiteLevel tag and the maximum computed black level for the sample plane.
Clipping
The rescaled values are then clipped to a 0.0 to 1.0 logical range.

The above is taken from Adobe's DNG spec.

Given Aperture's tardiness in supporting camera RAW, it suggests to me that they should create an API (RAW.plist is apparently only part of the deal) so that 3rd parties or the camera manufacturer could provide converter plug-ins.

G.

Forgot to add.

This approach would mean Aperture/OS X would need to support Linear DNG, which strikes me as reasonable and appropriate.

G.

The test question is whether Adobe's DNG Converter will handle a camera's raw files. As far as I know Adobe is & is likely to stay ahead of Apple in this. So if Apple concentrates on the .dng file, they can let Adobe do the hard work for them.

Yes, it makes sense.

Unfortunately it's human nature to think more about what affects oneself than what affects the big picture. So it's more common to say "support MY camera" than "support all cameras"

That said, it seems to me that it's absurd that Aperture/OSX don't properly support universal linear DNG. They don't need to be able to save 'em (though it would sure be nice) but they definitely need to be able to read 'em - even if we are stuck with Adobe's (free, fine) converter, at least we'd be able to use any camera at any time without worrying about Apple's support. Seeing as the format is freely documented and open, it would sure make a lot of sense to support it. Come on Apple! 🙂

Thanks for the feedback. We're aware that many users are interested in seeing wider support for DNG and you can be sure that this will be taken into consideration as we move forward.

Joe Schorr
Sr. Product Manager, Aperture
Apple

Hi Joe,

pleased to hear you seem to take this seriously. Please put me on the list of those desiring DNG support!

Oliver

I thought that conversion to DNG was suppose to protect you if the original raw format went out of use and there were no converters available for that raw format. It looks as if even if you convert to DNG using Adobe if the raw converter (e.g. Aperture) is not designed to handle that specific camera's converted Raw to DNG file you are out of luck. This seems to defeat the whole purpose of DNG. I thought that once you converted to DNG any program that had the ability to read DNG files would work. Not so?

MacBookPro, 2GB, 2GHz Mac OS X (10.4.6)

Francis, most apps that support DNG do indeed work as you hope, but some do not. Here's hoping that Aperture becomes one of the former 🙂

(FWIW, I do not use DNG - but I think it is a promising format and one that could ease the woes of many of us who use esoteric equipment.)

I thought that conversion to DNG was suppose to
protect you if the original raw format went out of
use and there were no converters available for that
raw format.

This is a false hope.

As noted, DNG only stores the RAW photosite data, translated into a form that programs can easily get at. It actually cannot even do this much for all cameras today, but let's pretend it could.

So you have the raw photosites - now what? Now you have to do the hard job of de-mosaicing the data, converting all of the seperate r,g,b values into real pixels. But wait, not all of the cameras use the same pattern - in particular Fuji. So you have a RAW converter reading a DNG that may run into an "unexpected" pattern it knows not how to convert.

The sad thing is, the worry you had about not being able to read RAW files in the future is already solved by a program called "DCRaw". This source code, free for all, lays out exactly how to read this exact same RAW photosite data from a file and even de-mosiac it (though a simple de-mosaicing). If you save off a RAW file on a disc along with a copy of DCRaw I can guarantee that in 100 years you will be able to use that code to parse that file.

Consider from this the other aspect of DNG I really don't like - if you have a DNG file, you have no way of knowing what is REALLY in that file. Is is pre-converted linear RAW data? Is it straight-up bayer pattern data? Is it a Fuji rotated data with extra dynamic range sensors? You can't know from the extension, and as a result have no idea if any programs you have will parse it correctly or not. At least with JPG or TIFF or even a normal RAW file, either a program reads that format or it can't. With DNG you will pretty much always have a subset of DNG files you cannot read.

So my question is, if you can always be sure you can read a RAW file in the future, and you can't be sure conversion to DNG will let any program but Photoshop read your file - what is the point? There are two things it gives you that make life a little easier, one is smaller file sizes (if you opt not to keep the original RAW and trust the conversion drops no data), the other is ease of adding metadata into the file itself. The first I would say is not as crucial as HD space is pretty cheap, the second is useful but you can always use sidecar files with RAW files - and that's only a burden if you need to move away from a managed editing solution like Lightroom or Aperture.

Some cameras are starting to use DNG directly as a native RAW format but I've already stated why I think that is not a good idea - with DNG you don't know if it's a RAW file direct from some camera or an alien format that holds data you don't know how to parse.

I'm NOT an expert, but I think this may be misleading in one crucial way. As I understand it, the ultimate claim of DNG is not that the .dng file itself will always be readable, but rather that the code that creates it is open, fully documentable, and therefore possible to reconstruct when all camera makers' s/w devel teams are living in caves beside mountain pools with steadily diminishing stocks of fish. It's at least possible to write a brand-new app that will decode any .dng file. No proprietary program can claim that, or particularly wants to claim it. (Apres moi le deluge, they say.) So it's a fairly profound claim about longevity.

That's if I understand correctly. Always a big if.

I believe you're mistaken Kendall.

Once a file exists as a DNG, it can be read by any app that fully implements the DNG spec.

dcraw, on the other hand, although a truly remarkable piece of work, implements camera support on a per-camera basis. It is a toolkit for decoding files from a vast number of cameras and it is near-universal at the moment, but it follows a very different design philosophy.

While we should all be deeply grateful to Dave Coffin for the work he's done (and continues to do) on dcraw, it is no panacea. Neither is DNG of course - but the promise of DNG is a real one, and one to be applauded rather than feared. An open and documented format is far more desirable than a toolkit that can open myriad closed formats.

Hi Charles,

No Kendall is not mistaken.

DNG is a standard for a file-format. Actually it just a special kind of TIFF file, and as with TIFF you have a file format that you know how to read, but one thing is to read it, another is to able to understand what you read. The DNG standard does not say how you should intrepid the data, just how to read it. Just like you can have a TIFF file where the data is compressed by a ZIP algorithm. Where TIFF reader would be able to read the data, but a lot of old TIFF readers do not understand that the data can be ZIP compress, e.g.. it cannot uncompress it. I can create a TIFF that fully conforms to the standard but other programs cannot understand. Photoshop does that. A photoshop file contains a lot of information on layers etc. that only makes sense to Photoshop.

You can create a standard for the data in a DNG file, and support that standard, but then you already have come kind of RAW conversion going on to create this. If reading a Raw file was just a case of mapping RGB values of the censor, you could just have a normal TIFF file with a ICC profile for that sensor. No need for anything special. Unfortunately you need to do more than that, and that is specific to each type for sensor.

Best regards - Per.

Thanks for the clarification, sorry I misunderstood.

Here's a question though - why is it that old versions of Photoshop that lack specific camera support can read DNGs made from newer unsupported cameras?

I understand that Adobe has a head start on this stuff since they created the format and have vast resources to throw at it, but doesn't the Photoshop example imply that it is at least possible to use DNG as a universal format?

Hi Charles,

Well I think the most import aspect of the DNG format is the possibility of changing the file in a controled way. This way Aperture, Photoshop etc. can store there changes they make inside the file without those annoying sidecar files.

I don't think we will see a total standard on this because all the different players think that there solution is the best, and not all sensors are born equal. Noise Ninja is the best for noise reduction, Capture One has the best colors, etc. whatever you preferences is.

DNG is an improvement not a silver bullet, but it should be the Camera manufactures that implement this.

Best regards - Per.