Bart,
I think you may have answered a question I didn't ask. However, your response was very interesting, thank you, and has raised additional questions.
Returning first to my original question:
The relatively dull, low local contrast, impression that the initial Raw conversion gives is typical for a High Dynamic Range capture. The solution is local contrast adjustment...
With respect to the above, my confusion derives not from the fact that local contrast
can be perceived as low after initial RAW conversion - perhaps the photo was shot on an overcast day, for example - but that (to me) you seem to suggest that local contrast will be low
independent of photo content.
My understanding is that (as Jack noted) digital cameras record light level linearly, and hence tonal relationships as they exist at the time of capture. It is also my understanding that the human eye/brain sees nonlinearly, and that a curve is therefore applied to the linear data during initial RAW conversion in order for the image to be perceived as correct when displayed.
If initial RAW conversion reproduces contrast as it was perceived, from local to global contrast inclusive, what causes local contrast to be low?
With regard to your response:
I've attached a step-wedge example of how that works, for a normal local contrast enhancement like using a high radius USM with low amount (a simple Photoshop enhancement), and Topaz Clarity that uses the Mach band effect to increase tone separation between steps (only the Low contrast control was used, there are three more and some other controls).
I can see the contrast increase/decrease edge-effect in the first (USM) example (which can give rise to halos), and the Mach band effect over the 'tread' of staircase steps in the second (Topaz Clarity) example.
I was initially confused why, in the latter example, if only the Low Contrast control was used the upper 2/3 (say) of the step-wedge was not unaffected. However, I assume it's because absolute light level is irrelevant and it is the
relative difference in light level between neighbouring steps that determines if the Low Contrast control has an effect, and if so by how much. Is this correct?
In a real e.g. landscape image that works in a similar fashion, but much more complex, and at more contrast levels, and halo free.
If one were to take an increasing number of contrast levels into account, at the limit would the result be...deconvolution sharpening?