Adalbert wrote: ↑Sat Jan 09, 2021 6:16 am
I have compared DMap interpolated with "Bicubic", "Lanczos2", "Lanczos4" and found no difference.
But in general, DMap performance is much better than PMax, regardless of interpolation method.
Does it depend on the blue scales or my setup?
In general, DMap is better at handling simple geometries that do not have troublesome front/back overlaps, while PMax is better at handling complicated geometries such as overlapping spines or hairs. This is because DMap retains the original contrast, colors, and noise, but is vulnerable to loss-of-detail halos around edges, while PMax is much less vulnerable to loss-of-detail halos, but accumulates noise and often changes contrast and colors. At large NA, there is also the issue that DMap is much less vulnerable to the "squirming around" effect shown
HERE.
The scales here have rich colors and only a few shallow front/back overlaps, so they are a natural match to DMap. I would stack with both DMap and PMax, then flash-to-compare, just to check whether DMap might have missed some detail I would care about. I would not expect to find any, but if there were, then I would retouch just those areas from PMax output into a DMap master.
Regarding interpolation method, that becomes significant only when source images are sharp at the pixel level, say effective f/8 or wider on APS sensor. In this situation color can be important because short wavelengths diffract less, which produces an optical image that is sharper and contains finer detail.
Countering that, with most sensors, is that the Bayer filter pattern places only one blue-sensitive pixel in each 2x2 block, with blue for the other pixels being filled in by interpolation during the raw conversion step. The result is that the stacking algorithm never really has to deal with an image that is sharp at the pixel level in intensely blue areas. So, as a matter of practice, I would expect these intensely blue scales to be less sensitive to interpolation method, compared to scales with a more neutral color.
--Rik
