MarkII said:
(And if you think my analogy with print is invalid, you need to *explain* why. I may be wrong, but simply repeating your assertion that this is so does not show it to be the case).
I think this is a critical point, and possibly the root of the contention of the "DXO DR naysayers." As someone who prints a lot myself, perhaps I can offer some insight.
Assuming you print at
native resolution, printing does not average the original amount of information into something less. A print at native resolution represents the same, original, fully detailed image information at a higher density. That higher density may be anywhere from three to six times greater than the 100ppi of my screen (or even more dense, for those who use a 72ppi screen). That is very different than downsampling, which is destructive to information. Generally speaking, I downscale my images for display online. I print at native size at home, or perhaps slightly enlarged, and I might upscale (at a lower PPI) for large canvas prints from a lab. Depending on the amount of cropping, I might print as low as 8x10 with a small amount of downscaling (no where near a two-fold reduction for proper averaging, though), although most of the time it is 11x17", 12x18", 13x19" (the latter being my most common print size, usually at 300ppi).
There are other problems with DXO calling their rated DR "Print DR", though. Assuming you are using a godly form of paper, such as Innova FibaPrint Gloss, which has a dMax of over 2.7, you might be able to get 7 stops or so from a print. Your average fine art print paper has a dMax randing from around 1.3 to 1.5 on average to 1.75 or so for some of the more recent higher-end fine art papers. That gets you maybe 5-6 stops of DR. Most papers also don't have particularly high white points. Again, Innova FibaPrint bleached or bright white glossy papers have a pretty high brightness, and the Moab Lasal papers might be some of the brightest papers available with the highest L* I've ever seen (although they achieve it via OBAs, which require proper lighting properly produce the papers full DR.) Despite that, none of those papers, even when printed with top of the line pigment inks like Lucia or UltraChrome, will offer much more than around 7 stops of DR.
So that takes us back to the definition of DR. I'm happy to accept that DXO has a purely mathematical interpretation of DR, the ratio between white point (maximum saturation) and black point (noise floor). Again, though, I am not sure it is a useful or realistic definition of what dynamic range is. When one thinks about the value of dynamic range in digital photography, the first thing that usually comes to mind is the ability to recover useful detail from deep shadows. I say from the shadows, as I think any photographer who uses digital knows that it is critical to preserve the highlights, as once they are clipped, detail is well and truly gone. Since detail generally "fades" into noise on the shadow end, an improvement in photographic dynamic range has the benefit of improving one's ability to "recover", or pull up, detail out of the deep shadows.
Now, in this respect, I don't think anyone who has been involved in this debate will honestly dispute the fact that Sony Exmor sensors offer more dynamic range. That has never been in dispute...its a simple fact, clear as day for anyone who has seen or directly used a Nikon RAW image from any camera with an Exmor sensor. The dispute on record here, if I may define it according to my own views as well as that which I've read from other DXO DR naysayers, is this:
What value does DXO PrintDR (the mathematically derived ratio between white point (maximum saturation, FWC) and black point (electronic noise floor)) have in a real-world context?
From the standpoint of simply moving the black point in a downsampled image, the only thing that occurs is shadows become darker. One LOSES information during the process of downsampling, so the primary benefit of having additional DR in the hardware no longer applies. In the context of viewing images on a computer screen, primarily done via the web, having a deeper black point might be valuable. Computer screens generally support a much deeper black point than actual prints on paper (particularly prints on high quality fine art paper), although none actually support 14 stops of DR regardless, and the average consumer screen is only 6-bit, so roughly the same DR as a print.
When it comes to
real print, assuming one is printing at native size, or an upsampled image, original detail is preserved or slightly softened, but none of it is
lost due to downsampling. Regardless, assuming one even does significantly downsample a D800 image so they can print at 8x10", even printed on the highest dMax papers on the market with the brightest L* rating, your going to get HALF the DR you should supposedly be getting from DXO's 14.4 stop Print DR rating. If we assume you tweak the white and black points, curves, and levels in Photoshop to manually and ideally compress all that extensive 14.4 stops of DR into the 5-7 stops of DR your paper is capable of, then the additional mathematical DXO DR (darker black point) offered by downsampling is still of no benefit. It might actually make it more difficult to compress a greater range of shadow tones into the limited dynamic range of your paper, resulting in some funky tonality.
These are the issues I have with DXO's "Print DR" statistic. It is an unrealistic number, purely mathematical in derivation, that does not seem to translate into any real-world improvement in "print". It MIGHT offer slightly better blacks when downsampled images are viewed on the web. Blacks might be just a bit richer, assuming someone actually has a properly calibrated screen with high enough bit depth to actually support it. The average home user still uses a 6-bit screen. Most serious photographers have an 8-bit screen, and some serious professionals might have thousand-dollar 10-bit screens. At best, an observer viewing a photo on the web will be able to observe about 8-10 stops of DR, although on average we are still back to 6 stops on average.
At best, DXO's downsampled DR rating should probably be called
Web DR. It is not detail-preserving Photographic DR, as upon downsampling you lose detail. It is definitely not Print DR, since a print is inherently more about color richness and gamut than white-to-black point dynamic range. The depth of blacks sometimes matters in a print, however the deeper your black point in print, the harder it tends to be to actually discern fine shadow detail. Things look richer and more contrasty, but not necessarily more detailed. Papers with a higher white point AND slightly less dense blacks tend to look better, despite having far lower dynamic range than the original photo.
So, what is the value of DXO Print DR? Realistically, practically, physcally...what do I actually gain by downsampling my full-detail RAW into a smaller-sized TIFF? For that matter, what value does DXO Print DR have if I save as a compressed JPEG for viewing on the web? Are we really just talking about a DXO weighted
score, and nothing more? If so, should it really be called Dynamic Range, or is there a better term DXO could use that wouldn't come off as some kind of sketchy maneuvering (real or simply perceived) of their results in favor of a major monetary contributor?
BTW, resorting to personal attack as a means of argument demonstrates weakness in your own opinion. If you truly think people simply listen to me because I'm a dumb guy who just sounds smart, well, might not want to weaken your own position like that. I might dumly conjure up something intelligent in retaliation. Just a thought. 
