Demonstration of X-Trans Under-the-hood RAW Spatial (Noise) Filtering

57LowRider wrote:

Has anyone tried first-gen X bodies like the X-Pro1 or X-E1? It would be interesting to see, as the whole fuss about high ISO skin smoothing started with 2nd-gen, and that was buried in the system.

In our original post, we looked briefly at the XT10 & found its dark frame histogram was truncated indicating it is also filtered.

Before buying my 1st Fuji, I collected dark frames from several models & rented an X-Pro2. The dark frame histograms from all show signs of filtering but it differs by model. Heres the X-M1 & X-Pro2:

X-M1

X-Pro2

The X-Pro2 looks like the XT2. You have to look closely for the small steps in the histogram. Dark noise is random & should have no pattern. The XM1 is much more obvious & like the XT10. (From the recent tests, the X-T2 & XPro2 appear to also slightly clip blacks as well as apply spatial filtering to reduce long exposure noise. The XT3 does not appear to clip blacks.)

At the time I was first trying Fuji, I didn't have RawDigger nor understand any of this.

My early untracked star field images from the XT10 & XPro2 showed the characteristic missing bright cores from dim stars caused by filtering but I mistakenly chalked that up to lack of tracking & lens blur. Bright star cores are visible down to a low brightness level & then disappear for all similar stars. Weak colors are affected too.  This is definitely subtle! Star images from the X-T100 don't do this.

XT10

X-Pro2

It was only after I got a tracker, stopped my lenses down a bit & was still frustrated w/ muddy star fields that I began to dig deeper & learned of the filtering.

FWIW some Nikons apply filtering to exposures beyond 1/4 second. At least Fuji waits til 5 sec.

As for waxy skin & green foliage, these tests do not reveal filter for short exposures but it is very hard to detect filtering generally.