da Schnozz writes:
<<That is even more true with Canon sensors than the others. They biased
<<towards light sensitivity than color sensitivity.
Yes, Canyon sensors in general have had a less dense CFA (colored filter
array) than most, especially /Sonnie. This was a way for Canyon to improve
higher ISO performance at the expenses of color rendering. The algorithms to
adjust for a less dense CFA have become quite refined (had been some type of
least squared minimization of errors but has evolved, defer to the Schnozz on
that). The color accuracy of a sensor has been theoretically quantified by the
SMI---- as I posted before:
"The sensitivity metamerism index (SMI) is defined in the ISO standard 17321
and
describes the ability of a camera to reproduce accurate colors.
The SMI varies depending on the illuminant and purportedly is independent of
the
converter. Sonnie tends to do well here with a denser CFA but truth be told
the measure in practice is noisy above 80 and not very good at discriminating
the sensors. Purples and true
violets are notoriously difficult."
If one compares the spectral sensitivity of human cones (excluding
tetrachromats) vs a typical cam sensor one can anticipate it would be
difficult to devise a scheme where the two agree on color matches--so called
"Luther-Ives conditions." This is defined as when the sensor can distinguish
colors exactly as
the human eye and is possible if and only if the spectral responses of the
sensor can
be obtained by a linear combination of the eye cone responses. These in
reality doesn't happen. In practice it is unlikely any cam system any time
soon will meet these conditions for most observers under most illuminants.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4299059/figure/f1-sensors-14-23205/
CFA's have trade offs by nature. Xtrans colored filter array is designed so
the "green" raw channel has more coverage but less positional symmetry than in
a Bayer sensor
and as a direct result there is less high-frequency luminance
"miscalculations" in the interpolation, giving LOWER NOISE in raw conversion.
The larger B to B and R to R distances necessitate a large chroma smoothing
radius resulting in "watercolor" effects or artifacts- some converters seem
to smudge detail in the process as well -balance seems different with different
converters. The converters do seem
much better now after some evolution and don't hear as many
complaints--probably just took awhile to catch up.
Accuracy, in any event, like resolution may be over-rated. A pleasant color
rendering, and being able to over-extend the sliders to 11 may be just as or
more important.
Sometimes off-color, Mike
--
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