Uuglypher Loc: South Dakota (East River)

Examine....thoughtfully examine...these two images from the same image file, then get together with your ESL instructor and work your way through Reichmann's two essays, and Martinec's article. It all should, eventually, come together for you.
FYI The snow detail was a high VII to lowVIII.

SOOC; EBTR with 1.7 Stops ERADR,

(Download)

Post-tonal normalization

(Download)

Apaflo Loc: Anchorage, Alaska

Evasion won't work. Quote anything in the cited articles that says the benefit of ETTR is to "recover highlights".

You are simply mixing metaphors. They talk about boosting exposure to the maximum, which has a side effect of producing a SOOC JPEG with washed out highlights (they are totally ignoring that JPEG), and when the RAW file is post processed it has the benefit of recovering detail in the shadows.

Why you want to even look at the SOOC JPEG is a mystery. The only use it has is that the camera produces an histogram from it, but it has zero value for viewing.

Rongnongno Loc: FL

If you expect this thread to survive the interference please do not answer the 'whale'.

Use the 'ignore button' in your head!!!

By the way 'whale' is in reference to his origins and the space this critters takes where ever he post.

Uuglypher Loc: South Dakota (East River)

Thanks for your comments, Rongo.
Actually the images were posted because they illustrate quite well the ease of integration of the Zone System of Exposure with use of the Extra Raw-Accessible Dynamic Range (ERADR) in Expose Beyond the Right (EBTR).
The camera used has one and 2/3 Stops of ERADR, of great utility in permitting capture of image data of the highest possible Signal-to-Noise ratio.

selmslie Loc: Fernandina Beach, FL, USA

My main concern regarding a camera's ERADR is that it may vary with ISO the way that dynamic range (DR) does. Go to http://www.dxomark.com/ and look your camera's measured DR. You will see that it drops significantly as the ISO is increased. For example, at ISO 100 a D810 delivers about 14 steps of Ev, and a Canon 5Ds about 12.5. At about ISO 9000 both cameras achieve only about 8 steps. It may well be the case that ERADR also drops as the DR shrinks. So, as you have said elsewhere, you should measure your ERADR under your normal working ISO. However, if you often work at two widely separated ISO settings, you should probably test them independently.

A second consideration is that, when measuring ERADR, you should do it with the type of scene you normally encounter. If you do a lot of landscapes at low ISO with the sun behind you (more or less) on clear days, test that scenario. The ERADR may not be quite the same for an overcast day or twilight shot. It may be difficult or impossible to measure ERADR with a back-lit scene or a scene with a significant amount of specular highlight content.

Thirdly, you are basing your estimation of ERADR on something that is not very precise - the histogram for the camera's JPEG. Don't expect to come up with an exact number. Consider that a finding of 1.5 might have a margin of error of maybe +/- a third of a stop or even more. You won't notice the difference it you sacrifice a little of the ERADR as a safety margin.

And finally, don't be too confident in applying your measured ERADR to a scene that varies from the norm. Trying to "nail it" with a single shot may be risky. If you went to some effort and expense to reach the location, bracketing your shot may save you. After all, you are not fishing for marlin - you don't need to give it a sporting chance by taking a single shot.

Apaflo Loc: Anchorage, Alaska

Just use UniWB, and the ERADR will always be zero.

selmslie Loc: Fernandina Beach, FL, USA

I have used it, thanks to the information you provided, and it does not result in an ERADR of 0. If you had ever actually used it you would not say that.

Apaflo Loc: Anchorage, Alaska

I'm sorry that you still haven't figured out how do it right.

Are you still getting red and blue multipliers higher than 1.7??? :-)

But the simple fact is that UniWB will produce a difference between the RAW data clipping point and the JPEG data clipping point that is within 1/10 of an fstop.

The most recent effort that I've made at generating a UniWB curve for the D800 produces White Balance multipliers of 1.0000 for Red and 1.0039 for Blue. That means that Red and Green will clip at exactly the same for RAW data and JPEG data. The Blue will be 0.4% higher in the JPEG than in the RAW.

Figure out how much of an fstop 0.4% is! That is your ERADR value for a scene with very high levels of blue, but of course if blue is more than 1 stop lower than either the red or the green channels, then ERADR is more exactly 0.0.

selmslie Loc: Fernandina Beach, FL, USA

The closest I could come with my D610 at ISO=100 and a full G=6 bias was at 4760K, red=1.2265625 and blue=1.1796875. At 4550K the red and blue coefficients are reversed implying that they would be close to the same value at 4655K if I could select it, which I can't. The ERADR I measured with this setup was about 1 full stop.

Maybe the problem is that you do not now how to properly measure ERADR. I suggest you review Dave's instructions and try again.

I tested the same scene using a daylight setting of 5880K and a neutral G/M bias and found an ERADR of over 1.3 by simply using the RGB histograms. This took a lot less effort.

A different scene or a different ISO might have yielded different ERADR values but there is no reason to expect that UniWB would turn the histogram of the JPEG into a representation of the full raw range.

Based on everything I have seen so far, UniWB appears to have been a brief episode of lunacy in the evolution of digital imaging - long on promise but short on delivery. RIP.

I have no way of setting or measuring exposure compensation in the camera in 1/10 stop increments and neither do you (±5 EV in increments of 1/3, 1/2 or 1 EV according to the specs) so the precision you claim sounds like puffing.

Apaflo Loc: Anchorage, Alaska

As I've previously demonstrated rather well, I can easily measure ERADR within less that 1/3 of an fstop for any RAW file.

Dave's measurement is not accurate.


You aren't yet understanding what UniWB does. When the multipliers are 1.000 for both red and blue, the JPEG histogram will look exactly like the RAW histogram.


It has no benefit for anyone that cannot understand how it works. And it is rather technical, so for many people it can't help. Even for those who understand and can use it properly, the major detraction of not being able to show a preview on the camera, because of the sickly green cast, makes it less than useful.

And last but not least, just how often does anyone need that kind of exposure accuracy?


Still don't understand the technical in and out, eh?

Whether you can set EC within 1/3 of a stop isn't important. But that does mean you can get exposure to within 1/6th of a stop, but that is precision rather than accuracy. Given a histogram display that is accurate within 1/10 of a stop, that 1/6 is accurate too.

Guessing at what ERADR (or assuming it is fixed) puts your exposure accuracy at maybe 1/2 or 2/3 of a stop.

selmslie Loc: Fernandina Beach, FL, USA

Of course I understand it but since there is no way to set the red and blue multipliers to 1 without downloading a file and then dealing with the green screen, UniWB is useless.

You can claim all of the precision you like but if you have no way to apply it when you are taking a photograph, it is pointless.

Exposure is not a precise scientific concept. It is an aesthetic decision based on the fuzzy issue of how you want to render highlights and avoid noise in a particular scene.

An additional 1/3 or less increment of exposure will not produce a visible improvement in noise and it will only slightly increase the odds that a small proportion of your highlights will be blown. It's like counting the beans on your plate - quibbling over precision is absurd.

Using a normal white balance and watching the RGB histograms is not only easier and more efficient than UniWB, it is as precise as anyone needs to get.

Apaflo Loc: Anchorage, Alaska

So what's all this noise about ERADR?

selmslie Loc: Fernandina Beach, FL, USA

It's easier to determine without UniWB.

Uuglypher Loc: South Dakota (East River)

ERADR ("Extra Raw-accessible Dynamic Range" is simply a more specifically descriptive name for "headroom" or " Stop Slop", or, simply, the "unused dynamic range" beyond the clipping warning of the JPEG-adjusted histogram explicity recognized by Reichmann in 2003 and by Fraser in 2004...and by innumerable photographers since then. It is easily determined and as easily used. If you know how to ETTR, just add your camera's ERADER to the ETTR exposure under reasonable circumstances (as summarized by Fraser) and "Bob's y'r uncle!

You obviously haven't read...or at least haven't understood...Fraser's "Adobe White Paper" of 2004 cited many times previously. Really, give it a good, thoughtful read! It'll help immensely.

Uuglypher Loc: South Dakota (East River)

All good points, and all, in essence, stated by Fraser in his "Adobe White Paper" in 2004.

"RAW Capture, Linear Gamma, and Exposure “ Adobe White Paper, 2004,

http://www.adobe.com/digitalimag/pdfs/linear_gamma.pdf