Lightroom: DNG or RAW

[Daniel Browning]

Thanks for sharing, Gabor. By the way, your posts are often rife with opportunity to quote out of context:

...any software, no matter from which corner it comes, is guaranteed error free...

 Reminds me of Knuth for some reason: "Beware of bugs in the above code; I have only proved it correct, not tried it."

But if you go to process that CR2 again using the new version of the software, then even though you didn't touch any controls, the appearance of that CR2 has changed since you last looked at it.

Thanks for the post, Eric. The appearance changing with new versions is expected and normal. The reason I quoted that thread was because it shows that the appearance changes differently for DNG than for the original raw, contradicting Nick Rains' position that archiving the DNG would be the same.

[madmanchan]

Now that I understand the lie of parametric editing I'm fine with this.

Can you please clarify? In my view, parametric editing has never been about preserving rendered results (even approximately). Rather, it is largely about preserving the original raw data intact, regardless of how the software chooses to interpret it. That is, the software can continue to evolve and improve, but the original data should not change.

[DarkPenguin]

Can you please clarify? In my view, parametric editing has never been about preserving rendered results (even approximately). Rather, it is largely about preserving the original raw data intact, regardless of how the software chooses to interpret it. That is, the software can continue to evolve and improve, but the original data should not change.

Why do you need parametric editing for that?

[Panopeeper]

"Beware of bugs in the above code; I have only proved it correct, not tried it."

I do swear that my programs are error free, but I would not bet on that.

[Nick Rains]

The reason I quoted that thread was because it shows that the appearance changes differently for DNG than for the original raw, contradicting Nick Rains' position that archiving the DNG would be the same.

Seems to me that if you use different software to try and get the same results, you may or may not be successful. I admit to being surprised that a 3 year old DNG produced different results compared to processing the original CR2 RAW. Maybe Eric has an opinion on why this might be so.

However, just to check my facts, I just did this:

Convert a file to DNG.

Load both this DNG and it's corresponding CR2 into ACR5.2

Open both into PSCS4 having synched the settings, or left them both on default as I did.

Compare using difference blending mode.

Zero difference.

So I stand by my assertion that converting to DNG makes no difference; but evidently only using exactly the same software for both DNG and CR2. Therefore it's not the DNG format that is the 'culprit', it's the software that processes it.

[madmanchan]

Why do you need parametric editing for that?

You don't.

Parametric editing is not a requirement for non-destructive workflows. However, it offers several advantages over pixel-based edits. First, the edits themselves are much more compact. Hence you can work with multiple renderings of a given raw file (e.g., a color version, a neutral B&W version, tinted B&W version, versions with different color profiles, etc.) with little overhead; syncing edits (e.g., white balance, a given split-tone setting, hue twist, etc.) across a large number of images is also very efficient.

Another advantage, in my opinion, is that the image processing application (e.g., a raw converter) can automatically arrange the image processing operations in the most effective and/or efficient order, regardless of the order in which you make the edits. This all simply falls out of the idea that the application is working with a set of instructions/parameters. This has significant implications for users because it relieves users from accidentally being, for instance, in the wrong color space when performing certain types of operations (often you want to be in a linear RGB space for certain types of operations, in a non-linear opponent space for other types of operations, etc.). Having the user perform these conversions back-and-forth in a direct pixel-based representation, whether manually or automatically via an action/macro, is quite error-prone and can have many unwanted side effects.

[Nick Rains]

Follow up.

I cannot reproduce the results of that DPReview thread.

I dug back into my archives, I archive the original RAW to DVD and it's corresponding DNG to external HD.

OK, DNG created back in 2006, opened along with it's original CRW file at exact same settings in ACR5.2 using the old ACR2.4 profiles.

Zero difference, completely black difference blend.

So, by my own experience and testing, DNG and RAW are entirely equivalent, even from old D60 files, as long you use the same RAW processor. AFAIC that's the end of it, if there is some subtle technical issue lurking here then it does not show up in the real world and I'm not really interested.

[Panopeeper]

I stand by my assertion that converting to DNG makes no difference; but evidently only using exactly the same software for both DNG and CR2. Therefore it's not the DNG format that is the 'culprit', it's the software that processes it.

This is not, what you have proven. You have shown, that ACR interprets the native raw file identically as the DNG file. Big deal.

What about trying this with other raw converters? Some of them process (or processed in the past) the raw file "normally", i.e. as the raw processor's designers/programmers decided, while processing the DNG file as Adobe decided. This is relevant regarding the color reproduction.

However, again, in my eyes this is not an argument for or against DNG. This is the question of interpretation: if you select the path of DNG created by Adobe's DNG converter, you decide for Adobe's interpretation, which is the same as if you convert the native raw file directly with ACR. If you process the raw files (native and DNG) with another raw converter, the results may or may not be identical.

I remember there was a time, when Aperture processed DNG files, but only those created from natively supported raw files; this indicated, thet Aperture supported the format but did not give a damn for Adobe's interpretation of that raw data.

[Nick Rains]

This is not, what you have proven. You have shown, that ACR interprets the native raw file identically as the DNG file. Big deal.

What about trying this with other raw converters? Some of them process (or processed in the past) the raw file "normally", i.e. as the raw processor's designers/programmers decided, while processing the DNG file as Adobe decided. This is relevant regarding the color reproduction.

However, again, in my eyes this is not an argument for or against DNG. This is the question of interpretation: if you select the path of DNG created by Adobe's DNG converter, you decide for Adobe's interpretation, which is the same as if you convert the native raw file directly with ACR. If you process the raw files (native and DNG) with another raw converter, the results may or may not be identical.
.

I have demonstrated what others have been disputing, that DNGs are not equivalent to the original RAW. They are, as expected.

As to processing in different RAW converters, well of course the results are going to be different. What's wrong with that? It's quite common to use different converters to process different files, some have strengths in different areas - that's why people like to keep their original RAWs, just in case they need to use, say, DPP for some subtle edit. In this case DNG is not the appropriate format, I've no problem with that.

I happen to use ACR almost exclusively- it's convenient to do so - and so DNG is an appropriate format to archive into - for me.