On 18/04/2024 22:44, Cousin Ricky wrote:
> THE ISSUE
> 
> ...
> 
> EXAMPLES
> 
> Example 1: the Dutch flag.  Steps 2 & 3 are combined.  Since no
> additional math is required on the colors, there is no need to declare
> them as identifiers.
> 
>   pigment
>   { gradient y color_map
>     { [1/3 srgb <32, 71, 133> / 255] // Steps 2 & 3
>       [1/3 White]
>       [2/3 White]
>       [2/3 srgb <170, 28, 38> / 255] // Steps 2 & 3
>     }
>   }
> 

Red, white and blue... it's more the flag of the Netherlands than of
Germany, isn't it?


Apart from that, a very good and useful explanation.
It's always good to get back to basics.




-- 
Kurtz le pirate
Compagnie de la Banquise

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On 2024-04-19 09:37 (-4), kurtz le pirate wrote:
>>
>> Example 1: the Dutch flag.  [snip]
> 
> Red, white and blue... it's more the flag of the Netherlands than of
> Germany, isn't it?

At least in English, "Dutch" means "of the Netherlands."  It does not
mean "Deutsch," although the words have a common etymology.

(To confuse things, there's also Pennsylvania Dutch, which *is* a
dialect of German, but that is another matter.)

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On 19/04/2024 16:27, Cousin Ricky wrote:
> On 2024-04-19 09:37 (-4), kurtz le pirate wrote:
>>>
>>> Example 1: the Dutch flag.  [snip]
>>
>> Red, white and blue... it's more the flag of the Netherlands than of
>> Germany, isn't it?
> 
> At least in English, "Dutch" means "of the Netherlands."  It does not
> mean "Deutsch," although the words have a common etymology.
> 
> (To confuse things, there's also Pennsylvania Dutch, which *is* a
> dialect of German, but that is another matter.)
> 

I read too fast and my English is really bad.
Sorry :(





-- 
Kurtz le pirate
Compagnie de la Banquise

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Op 18/04/2024 om 22:44 schreef Cousin Ricky:
> THE ISSUE
> 
> What is gamma, why should assumed_gamma be set to 1, and how should we
> use the sRGB keywords introduced with POV-Ray 3.7?
> 
> [snip]
> ---
> Copyright (C) 2024 Richard Callwood III, CC-BY-SA 4.0.

Excellent! Thank you very much indeed!

[Real Life: so much to do; so little time... :(  ]

-- 
Thomas

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hi,

Cousin Ricky <ric### [at] yahoocom> wrote:
> ...
> The first thing to remember is that POV-Ray has *one* and only *one*
> color format.  The srgb keyword does not create a different kind of
> color than the rgb keyword; it simply interprets its argument
> differently.  ...

(belated) thanks.

so, the "take away" is to not mix RGB types and 's' variants in the same scene ?
 and use RGB types only if values, due to arithmetic, may go "out of range" ?

(a sort of "conclusion" with recommendation would have been ideal)


regards, jr.

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"jr" <cre### [at] gmailcom> wrote:
> hi,
>
> Cousin Ricky <ric### [at] yahoocom> wrote:
> > ...
> > The first thing to remember is that POV-Ray has *one* and only *one*
> > color format.  The srgb keyword does not create a different kind of
> > color than the rgb keyword; it simply interprets its argument
> > differently.  ...
>
> (belated) thanks.
>
> so, the "take away" is to not mix RGB types and 's' variants in the same scene ?
>  and use RGB types only if values, due to arithmetic, may go "out of range" ?
>
> (a sort of "conclusion" with recommendation would have been ideal)
>
>
> regards, jr.

WHEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE!

'Round and 'round we go, when we'll stop NOBODY KNOWS!!!!!

https://news.povray.org/web.64b18904b039fa5d1f9dae3025979125%40news.povray.org









Can we do gamma again?  Oh please oh please oh please.....     ;)

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"Bald Eagle" <cre### [at] netscapenet> wrote:

> Can we do gamma again?  Oh please oh please oh please.....     ;)

Maybe our Cousin can add a simple demo what srgb input results in what rgb being
used?

#version 3.8;
global_settings{ assumed_gamma 1.0 }

#for (i,0,1,0.1)
  #declare c = srgb i;
  #debug concat(str(i,0,2)," : ",vstr(3,c,", ",0,2), "\n")
#end

maybe add splines to it to show the relationship.

or the relation with gamma in photography how exposure time and development time
influence gamma while having the same min and max density as a result. And how
you can play with photographic paper to compensate for gamma errors a bit or use
it for artistic expression, kind of changing assumed_gamma .... sorry, got
carried a way, thoughts of red lights and darkrooms


ingo

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Op 22/04/2024 om 19:18 schreef Bald Eagle:
> 
> WHEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEEE!
> 
> 'Round and 'round we go, when we'll stop NOBODY KNOWS!!!!!
> 
> https://news.povray.org/web.64b18904b039fa5d1f9dae3025979125%40news.povray.org
> 
> 
> 
> Can we do gamma again?  Oh please oh please oh please.....     ;)
> 

<large grin>

I imagine that hell is paved with white hot gamma, rgb, and srgb slabs....

-- 
Thomas

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hi,

Thomas de Groot <tho### [at] degrootorg> wrote:
> Op 22/04/2024 om 19:18 schreef Bald Eagle:
> > ...
> > Oh please oh please oh please.....     ;)
>
> <large grin>
>
> I imagine that hell is paved ...

Hell yes !!  (I only got as far as tarring & feathering) </grin>


regards, jr.

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"ingo" <nomail@nomail> wrote:

> Maybe our Cousin can add a simple demo what srgb input results in what rgb being
> used?

I totally agree about the darkroom - with the timer and trays - and the
thermometer.  Ansel Adams taught me a lot.

And we _have_ covered this topic extensively, and it's likely time that we ALL
put our heads together and hammered out some good macros with commentary, and
then putting together a scene / graph / animation would be trivial.

A spreadsheet would not be a bad idea either.

https://news.povray.org/web.5f8cb1fd76c60ba81f9dae300%40news.povray.org
https://news.povray.org/povray.general/thread/%3Cweb.60649d9bb9b7dccdd98418916e066e29%40news.povray.org%3E/?mtop=434374


I do believe it was stated somewhere above that POV-Ray takes into account the
effective scene gamma... so I would recommend digging around in the source code.


- BE

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