On 2022-02=28 15:06 (-4), Cousin Ricky wrote:
> 
> I massaged the colors in an attempt to eliminate the hue drift while
> keeping them suitable for linear gamma and metallic reflection.

I have rendered several variations of the demo scenes from the
scenes/incdemo/metals directory in the POV-Ray distribution.

Image incdemo-metals-old.jpg is a montage of the original metal demos.
Note that assumed_gamma was explicitly set to 2.2 for these scenes.  The
ambient on the ground plane was set to an outrageous 0.45, but it
doesn't seem that bad due to the non-linear tracing.  The baked-in
ambients don't look that bad at this unrealistic scene gamma, but the
"harder" finishes are much lighter than the softer ones, which doesn't
seem realistic to me.

The remaining scenes all use my new finishes, and have assumed_gamma 1,
and ambient 0.1 set on the ground plane.

Image incdemo-metals-encoded.jpg uses the original metal colors as
declared.  The colors are considerably less saturated, and the hues are
noticeably different.

For image incdemo-metals-decoded.jpg, the colors are decoded from gamma
2.2.  The colors are all very dark, and do not lighten up for the
"harder" finishes.  This darkness is why I proposed not decoding the HSV
values.

For image incdemo-metals-encv.jpg, only the hue and saturation are
decoded.  However, the colors now look too strong.

For image incdemo-metals-half.jpg, the saturation is half-decoded.
Because reducing the saturation affects our *perception* of hue (even
though the hue is mathematically unchanged), I also half-decoded the
hue.  As for why changes in saturation affect our hue perception, I have
no ides; you'll have to ask a color scientist.

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Attachments:
Download 'incdemo-metals-old.jpg' (162 KB) Download 'incdemo-metals-encoded.jpg' (170 KB) Download 'incdemo-metals-decoded.jpg' (171 KB) Download 'incdemo-metals-encv.jpg' (179 KB) Download 'incdemo-metals-half.jpg' (175 KB)

Preview of image 'incdemo-metals-old.jpg'

Preview of image 'incdemo-metals-encoded.jpg'

Preview of image 'incdemo-metals-decoded.jpg'

Preview of image 'incdemo-metals-encv.jpg'

Preview of image 'incdemo-metals-half.jpg'