RE: "In essence, Apple's new iPhones are taking multiple pictures at varying exposure levels, requiring noise reduction that creates a smoothing effect over the entire image, not just specifically on skin tones."
The Back 12 Mpx Wide-Angle & Front 7 Mpx image sensors in the XR, XS, & XS Max are BOTH brand-new (to AAPL) & support Full-Res 12 Mpx capture @ up-to 120 fps ... up-to eight OR nine photos total per Burst ... AAPL captures four @ intended exposure, four @ slightly different exposures, & ALSO one "special" (I believe).
AAPL uses the capability to support it's Smart HDR feature.
Because it's "sequential" & NOT "concurrent" captures, AAPL implemented @ the max speed of 120 fps.
The drawback is that they then needed to increase the ISO, which reduces Detail.
The iOS 12.1 implementation will very-likely NOT capture as many photos per Burst, which aren't really needed anyway.
One @ ideal exposure + one to two slightly UNDER-exposed + one slightly OVER-exposed is probably ideal.
The problem occurs on both the Front & Back Wide cameras / lenses / image sensors.
The problem is a direct result of AAPL raising the ISO to support Smart HDR.
It's an easily fixed problem.
BTW, every image sensor that AAPL uses that supports the following probably has the same issue (which means the Telephoto in the XS & XS Max very-likely ALSO have an updated image sensor):
- Extended dynamic range for video up to 30 fps