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DNG updated to allow RAW corrections: Digital Photography Review

 

Adobe has updated its DNG digital negative specification to allow a series of image corrections to be embedded in the file. Version 1.3 of the non-proprietary RAW file format allows a series of 'corrections and enhancements', which Adobe is calling opcodes, to be defined in DNG files. These opcodes include the ability to specify corrections for lens aberrations such as geometric distortion and lateral chromatic aberration that should be made to the RAW data when it's processed.

 

Adobe has this to say about opcodes:

 

"DNG 1.3 now includes opcodes, a defined list of operations and their parameters for performing complex activities in the raw file conversion process. These activities include corrections and enhancements that are beneficial when performed prior to the demosaic process but are difficult due to a camera's limited processing power. They also include corrections and enhancements that can only be performed after the demosaic process such as lens correction. By utilizing opcodes, photographers can maintain the advantages of raw mosaic data, giving them increased opportunity to improve their photographs with the maximum amount of image data preserved. The DNG SDK has also been updated to reflect the changes to the specification."

 

In keeping with DNG's non-proprietary ethos (Adobe has previously said it would like DNG to be taken on and independently progressed as an ISO standard), the full specification and Software Developers' Kit is publicly available on the company's website.

 

We've had a bit of a dig through the new specifications and blogged some of the things it tells us about processing that manufacturers are applying to their images

 

Whoa, sounds pretty fancy to me. When should we expect a firmware update for M8 / M8.2 with support to this new DNG version?

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That's interesting news... I even wonder if this could someawy lead to an UVIR correction WITHOUT filter, directly in firmware OR in the RAW developing session...

 

I doubt it. How would the software know that something appearing as magenta wasn't really magenta?

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I even wonder if this could someawy lead to an UVIR correction WITHOUT filter, directly in firmware OR in the RAW developing session...

No, it couldn’t. There is no way to tell color-shift caused by IR contamination from actual color. However, Leica could put opcodes for removing the red vignetting caused by the IR filter into the DNG file.

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No, it couldn’t. There is no way to tell color-shift caused by IR contamination from actual color. However, Leica could put opcodes for removing the red vignetting caused by the IR filter into the DNG file.

 

Problem is, that would only work for Adobe software. I very much doubt that C1 or Aperture or wherever else will ever implement opcodes.

 

Also, btw, the way I read the spec is that the vignetting correction is non-color dependent; aka you can only correct all colors at the same time. What you could probably do is to use the gain mapping function, which can be color dependent, and program a vignetting correction in there. But I still need to look at the code. As ever, the actual documentation is sketchy.

 

Sandy

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In my opinion this may be the beginning of the end of the DNG format as a non-proprietary standard. If in the future every DNG file will contain some camera manufacturer's specific 'opcodes' that in turn have to be supported by the image processing software - what will remain of the original DNG idea?

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In my opinion this may be the beginning of the end of the DNG format as a non-proprietary standard. If in the future every DNG file will contain some camera manufacturer's specific 'opcodes' that in turn have to be supported by the image processing software - what will remain of the original DNG idea?

 

Is that necessarily the case? What if the original raw file only contains data on camera and lens, and have the corrections generated in Lightroom and then added to the file?

 

I am not sure I understand all this well, but could this be a possibility?

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In my opinion this may be the beginning of the end of the DNG format as a non-proprietary standard. If in the future every DNG file will contain some camera manufacturer's specific 'opcodes' that in turn have to be supported by the image processing software - what will remain of the original DNG idea?

 

Not really. A DNG will always be a DNG. What Adobe is trying to do is allow the DNG converter, convert other RAW file formats (NEF/RWL/whatever), to a complete DNG file including the makers proprietary/specific lens, sharpening, contrast, whatever corrections. That way you will not need the makers specific software to get the best out of your images. Convert to DNG and open in ACR and still have all the in camera settings or correction retained.

Since the present M8/.2 camera does not allow any in camera settings, like sharpening, contrast & saturation, for the RAW DNG file output this update to the DNG specs has no meaning.

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Is that necessarily the case? What if the original raw file only contains data on camera and lens, and have the corrections generated in Lightroom and then added to the file?

What you are describing here is the situation as it is now. Raw files contain proprietary data that allow the camera vendor’s raw converter to derive and apply the necessary corrections. But then third-party raw converters are left out, so this wouldn’t work for Lightroom. With DNG 1.3, the camera can specify the necessary corrections in a non-proprietary way as opcodes, so any raw converter supporting DNG 1.3 could apply these. That is, DNG 1.3 is removing an important reason for still using proprietary raw file formats.

Edited by mjh
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Right... :o... I trivially forgot that a magenta fabric COULD BE INDEED magenta... :p

It’s not just that. The IR induced color shift can affect any color – skin color turns an unhealthy red, grass and foliage turn yellow/green, and so on. Other subjects of the same actual color remain unaffected, as they don’t reflect IR.

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I understand that Lens distortions and vignetting can effectively be removed provided the RAW file has this additional information. This is how it is made in the Hasselblad H3DII files, if I'm not mistaken. Until now H3DII users needed the Phocus software to be able to perform the DAC corrections (consisting of vignetting, distortion and CA) but seemingly, now we will be able to use Adobe CS4 (or even PSE 6/7).

 

Actually I tried it yesterday, but it seems that, even if it's made, user does not have the tools to play with the strength of corrections. So I couldn't know for sure.

 

I wish a similar workflow may be done for the M8 DNG files (with the corresponding work in C1 preferably), so the software may automatically (with manual override) correct for the vignetting, distortion and CA while converting the DNG files to JPG/TIFF.

 

I hope the M8 has enough internal memory for additional firmware information, or at least C1 may be developed to have the individual lens data to be used with the lens information coming from the EXIF data.

 

The system works quite swiftly in the MF (Hasselblad at least).

 

Therefore the lens design even is made with better compromises, like leaving vignetting occur more (which can be corrected easily later on) while concentrating on other points to make a system (camera+lens+software) to reach better output, which counts more than anything.

 

Best regards

 

Seyhun

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What you are describing here is the situation as it is now. Raw files contain proprietary data that allow the camera vendor’s raw converter to derive and apply the necessary corrections. But then third-party raw converters are left out, so this wouldn’t work for Lightroom. With DNG 1.3, the camera can specify the necessary corrections in a non-proprietary way as opcodes, so any raw converter supporting DNG 1.3 could apply these. That is, DNG 1.3 is removing an important reason for still using proprietary raw file formats.

 

Well, yes, but, and its a big "but" - only if Adobe's opcodes can keep up with how fast camera manufacturers think up new ways to correct things in software.

 

Personally, I think that probably does mark the beginning of the end for DNG as anything other than an Adobe format - I don't believe that Adobe will be able to iterate the spec fast enough to keep up with manufacturers and at the same time get any third party to implement the full spec. Right now, there is not a single complete implementation of a DNG raw reader other than Adobe, that I know of. And this just makes the problem worse.

 

Sandy

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Well, yes, but, and its a big "but" - only if Adobe's opcodes can keep up with how fast camera manufacturers think up new ways to correct things in software.

 

Personally, I think that probably does mark the beginning of the end for DNG as anything other than an Adobe format - I don't believe that Adobe will be able to iterate the spec fast enough to keep up with manufacturers and at the same time get any third party to implement the full spec.

Yeah, but then that’s what you get when you support all the idiosyncracies of individual cameras plus all the possible combinations of those, when obviously rather few of those combinations will actually occur – there is a huge space of possible raw file formats that could all be mapped to DNG, but this space is only sparsely populated. Small wonder that developers of raw converters supporting DNG are cutting corners by supporting only what is actually used.

 

I agree that the current list of opcodes may not be the final one. As you pointed out, the vignetting correction gets applied uniformly across all the color channels, and this should change. Still, once it becomes possible to code the main corrections using opcodes, this would already offer huge advantages to those preferring third-party raw converters.

 

As it is now, the mapping from shot parameters to correction coefficients happens within the raw converter. Camera/lens vendors are regarding the tables of coefficients as their intellectual property, so anyone attempting to replicate such corrections would have to determine the values empirically (which is what DXO does, for example). With the opcode approach, the mapping from parameters to correction coefficients would happen in-camera; while requiring more flash memory this would certainly be feasible and would open the market for third-party raw converters without requiring camera vendors to reveal their corporate secrets.

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The press release indicated that Adobe was offering this so that cameras without sufficient in camera processing power could apply as shot corrections as optional post exposure corrections along with the unchanged RAW file. The major camera manufacturers have never been very helpful to third party RAW development software vendors, although Adobe seems to hold a big enough stick to get some cooperation. I don't think this will change.

 

For the M8 there is a second reason to be doubtful of the benefit of this. The M8 applies its in camera corrections to the raw 14 bit data, and converts to perceptually appropriate 8-bit after the corrections are done. Applying the corrections after 8 bit encoding can never be as effective, sometimes leading to posterization, as SandyMC has found.

 

scott

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The major camera manufacturers have never been very helpful to third party RAW development software vendors, although Adobe seems to hold a big enough stick to get some cooperation. I don't think this will change.

Raw converters from camera vendors have rarely been overly popular with photographers though, and with the recent trend of raw conversion software growing into full-fledged workflow solutions, camera vendors would have to dedicate even more development resources just so they could offer something that customers would actually want to use. Canon, for example, doesn’t make money from distributing Digital Photo Professional with their cameras, so why should they even bother if they could leave software development to the likes of Adobe or Apple while still enabling software corrections – and without loosening the grip on their intellectual property? And then there are vendors such as Leica or Panasonic that don’t even have their own raw conversion software and need to buy a solution elsewhere.

 

For the M8 there is a second reason to be doubtful of the benefit of this. The M8 applies its in camera corrections to the raw 14 bit data, and converts to perceptually appropriate 8-bit after the corrections are done. Applying the corrections after 8 bit encoding can never be as effective, sometimes leading to posterization, as SandyMC has found.

I doubt we will see any existing camera model switching to use DNG 1.3 opcodes. It’s not that simple. For new models it’s a different matter.

 

Regarding the 8 bit encoding as applied in the M8, there is indeed an advantage to applying corrections first (in-camera) and only then compressing to 8 bits, but compared to applying those corrections later – i.e. using Sandy’s CornerFix –, that advantage is pretty slight. That’s why CornerFix works so well. The danger of posterization only lurks when converting the data to 8 bits again – after applying the corrections –, which Sandy consequently advises against. But that isn’t even an issue here: When a raw converter supporting DNG 1.3 would apply some corrections as specified by a list of opcodes embedded within the raw file, it would never save it back as raw data. Those corrections would only ever be applied as an intermediate step towards converting the raw data to a TIFF or JPEG file.

Edited by mjh
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Canon, for example, doesn’t make money from distributing Digital Photo Professional with their cameras, so why should they even bother if they could leave software development to the likes of Adobe or Apple while still enabling software corrections – and without loosening the grip on their intellectual property? And then there are vendors such as Leica or Panasonic that don’t even have their own raw conversion software and need to buy a solution elsewhere.

 

 

Perhaps because Canon regard it as part of the product they sell. I'm pleased they do since I only upgrade my PS every two or three versions and would need the dng convertor to process files from my latest Canon.

 

Somehow handing the processing of your proprietary RAW files over to Adobe does not seem to be a smart business move.

 

I'm sure the development of DPP is factored into the cost of the cameras in anycase and for me at least is one of the plus points for buying Canon.

 

Jeff

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Perhaps because Canon regard it as part of the product they sell. I'm pleased they do since I only upgrade my PS every two or three versions and would need the dng convertor to process files from my latest Canon.

 

Somehow handing the processing of your proprietary RAW files over to Adobe does not seem to be a smart business move.

 

I'm sure the development of DPP is factored into the cost of the cameras in anycase and for me at least is one of the plus points for buying Canon.

 

Jeff

 

Just think IF the camera companies stopped using a proprietary RAW file format and started using the Adobe DNG extension for the RAW file output (along with writing whatever changes/corrections that need to be made by the camera) of there cameras.

This would simplify the processing of all RAW file formats.

No need for Nikons Capture NX for NEF file. No need for for any other makers software to read all the information in there RAW file format.

This would simplify everythng along with long term storage.

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The points you make are correct but I fear that it would lead to a virtual monopoly position for Adobe - who are already too powerful in my view. Unless that can be avoided I would rather keep the Canon and Nikon SW. There are already universal file fomats, just not RAW.

 

Now Li ion batteries, they could be far more standardised for the future.

 

Jeff

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