AWB vs. UniWB experiment: the data

Started Aug 10, 2012 | Discussions thread
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Chris Noble
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AWB vs. UniWB experiment: the data
Aug 10, 2012

Please read this entire post before responding.

Many of us have engaged in spirited debates about how to obtain the "best" Raw ETTR exposure. This thread addresses one part of that debate: which is better, AWB or UniWB , for that purpose? This is an AWB vs. UniWB data-gathering experiment. We will post comparisons of AWB and UniWB shots of the same scene, same time, same camera & same photographer. The objective is to expose for the "best" ETTR in each case.

All scenes, lighting conditions and lighting sources are welcome.

Please follow the following guidelines, which have been worked out in this thread:

http://forums.dpreview.com/forums/read.asp?forum=1041&message=42216351

1) Put your name and submission number in the subject line. One scene per post please. You can post as many different scenes as you want.

2) Shoot the same scene with WB set for AWB and then for UniWB (or in reverse order). Post must include both RawDigger histograms and both PP JPGs . We are standardizing on a common RawDigger log-scale presentation format for the histograms. Instructions can be found here, thank you Gollywop for proposing a standard format:

http://forums.dpreview.com/forums/read.asp?forum=1041&message=42226322

3) Include information about your camera, exposure, compensation, and the method you used in setting the exposure; use or avoidance of VF blinkies and pre/post VF histograms, your compensation rules of thumb, etc. Screenshots of your VF information would be useful but not required. Also comments on how you PP'd the JPGs.

4) Tell us how many test exposures you made and how you iterated compensation adjustment before the final shot. Bracketing is not allowed for this experiment. By bracketing we mean taking multiple exposures and picking the best one based on looking at the JPG rendering or histograms after the series has been shot. We are not suggesting that bracketing is not a useful tool; but we want to limit the experiment. Submit the last picture you took with the AWB setting and the last one you took with the UniWB setting. No cheating.

5) Give us your summary evaluation. In your opinion, which WB gave you the best ETTR exposure, and the best JPG result, where in the JPG image "best" can be observed, and why. And other words of wisdom (Hint: the tie-breakers are often saturated highlights or noisy shadows).

6) Tripod use is welcome but not required.

7) "Best ETTR" means rightmost possible without intentional saturation of specular highlights (In practice, specular highlights are often saturated intentionally. Not for this experiment please).

8) If you would like to examine the Raw files, please send a private message to the poster. Or you can use a special Dropbox created for this purpose by Vlad :

http://forums.dpreview.com/forums/read.asp?forum=1041&message=42217380

9) Please resist the urge to post unless you are submitting an entry or providing restpectful, thoughtful feedback and questions. It would be nice to include as many examples as possible before we reach the 150-post limit. We are not in a hurry. Bookmark this thread though, it may often sink below the first Micro Four Thirds Forum page between submissions if we are all busy shooting.

10) It's easy to cheat. Don't. No reason to, and your mother is watching you.

11) This thread is not for you if (a) these acronyms mean nothing to you or leave you indifferent; (b) you would like to debate the value of ETTR, UniWB, or green casts in your VF; (c) you would like to learn about ETTR and UniWB; (d) you would like to program your camera for UniWB; (e) you would like to post something sarcastic, demeaning, inflamatory, off-topic or responding in kind to the same.

Sorry; we can't meet everyone's needs in one thread. Do a search and you will find ETTR and UniWB explained in abundance, on DPReview and elsewhere on the 'Net.

12) I'm sorry if these instructions seem either too onerous, narrow, wide or not useful. It's the best I can do. Thank you everyone for your suggestions in the guideline thread:

http://forums.dpreview.com/forums/read.asp?forum=1041&message=42216351

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