Return of Interesting article on DxO about 5D III and D800...

Started Apr 10, 2013 | Discussions thread
John Sheehy
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Re: not res
In reply to Mako2011, Apr 13, 2013

Mako2011 wrote:

John Sheehy wrote:

I really don't you know where you come up with the idea that I confuse resolution with sharpness or acutance

But you never define resolution in a way that puts everyone on the same point of reference.

Yes, I did.  I said that it is trend of contrast vs frequency (either based on the frame or the mm).  That is NOT perceptual, and has nothing to do with acuity or sharpness.  It is TOTALLY empirical.

I also said that it is a mistake to choose a single contrast threshold and define resolution monolithically, based on that, and suggested that aliasing be taken into account by bifurcating the trendline, with the upper trend taking into account lucky alignment, and the lower trend unlucky alignment.

It would be much like current MTF graphs, but it would take into account the discrete sampling frequency and the resulting bifurcation, distinguishing between real resolution of frequencies sampled properly by the sampling rate, and distorted/aliased resolution caused by under-sampling.

That leads to the same confusion DxO generates. I defined resolution above. Based on that commonly accepted definition... Is your measurement strategy in context?

What leads to the same confusion?  I suggested that monolithic resolution figures based on a single contrast are insufficient for digital sensors, and explained why.  I also suggested the bifurcation of the trends, and why it is needed.

The only time I have introduced perception was to explain why these things are needed to avoid being fooled by perception, such as when people are impressed by the acuity of 100% pixel views, ignoring the fact that this means bad sampling, and tells nothing directly about the maximum usable resolution of the image.

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