On 2020-10-15 1:05 PM (-4), Kenneth wrote:
> "Kenneth"<kdw### [at] gmailcom>  wrote:
>> "Bald Eagle"<cre### [at] netscapenet>  wrote:
>>> Hi Kenneth - this is something that I was concerned about, tried to
>>> address, and IIRC, did it backwards.
>>>
>> And you are correct-- your two macros are*reversed*  as to their respective
>> operations! Through no fault of your own: the Wikipedia formulae themselves are
>> REVERSED...
>>
> Well, I never like to base my ideas on a single source of information, so I
> looked at other web sources that have these 'color conversion' equations-- and
> ALL the sources I've seen match the order of the equations in Wikipedia.  So I'm
> obviously wrong about the two equations being 'backward' there. I gave this a
> lot of thought, and realized that it's our*use*  of those equations **in
> POV-ray** that makes them seem so. To really explain why would take paragraphs,
> and I'm still wrapping my brain around it. And I might put Ash to sleep...:-P

Indeed, the very reason I didn't chime in on this matter is that I 
sometimes get my directions mixed up on this, and didn't feel the 
confidence to take a hard look.  It can be brain busting.  Sometimes I 
get lazy (or frustrated) and just run a formula, and if the result turns 
out backwards, I know I need to use the other formula.

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