Cousin Ricky <ric### [at] yahoocom> wrote:

> POV-Ray 3.6.2 and earlier read image files incorrectly, although this
> can be fixed with a pigment function, which is what I did before 3.7 was
> developed.  (Thanks Jaime or Ive, whoever posted the function.)  The
> article might also explain why anti-aliased text in POV-Ray 3.5 looks
> heavier than in 3.6 and later.

Friedrich Lohmueller?

http://www.f-lohmueller.de/pov_tut/backgrnd/p_sky8.htm

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On 2021-03-08 2:23 PM (-4), Bald Eagle wrote:
> Cousin Ricky <ric### [at] yahoocom> wrote:
> 
>> POV-Ray 3.6.2 and earlier read image files incorrectly, although this
>> can be fixed with a pigment function, which is what I did before 3.7 was
>> developed.  (Thanks Jaime or Ive, whoever posted the function.)  The
>> article might also explain why anti-aliased text in POV-Ray 3.5 looks
>> heavier than in 3.6 and later.
> 
> Friedrich Lohmueller?
> 
> http://www.f-lohmueller.de/pov_tut/backgrnd/p_sky8.htm

No, the function I have uses sRGB non-linearity instead of a power 

original post, but this code is adapted from one of my old scene files.

-----------[BEGIN CODE EXCERPT]-----------
#declare p_Map = pigment
{ image_map { jpeg "myimage.jpg" interpolate 2 }
}

#declare fn_Map = function { pigment { p_Map } }

#declare fn_Adjust = function (x) //from IEC 61966-2-1:1999
{ select (x - 0.04045, x / 12.92, pow ((x + 0.055) / 1.055, 2.4))
}

#declare p_Adjusted = pigment
{ average pigment_map
   { [ function { fn_Adjust (fn_Map (x, y, z).red) }
       color_map { [0 rgb 0] [1 red 3] }
     ]
     [ function { fn_Adjust (fn_Map (x, y, z).green) }
       color_map { [0 rgb 0] [1 green 3] }
     ]
     [ function { fn_Adjust (fn_Map (x, y, z).blue) }
       color_map { [0 rgb 0] [1 blue 3] }
     ]
   }
}
-----------[BEGIN CODE EXCERPT]-----------

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Op 08/03/2021 om 19:04 schreef Cousin Ricky:
> On 2021-03-07 12:32 PM (-4), Robert McGregor wrote:
>>
>> That said, I just read this blog post about gamma, which I found very
>> enlightening and thought it might be helpful to others here:
>>
>> https://blog.johnnovak.net/2016/09/21/what-every-coder-should-know-about-gamma/ 
>>
> 
> Et tu, Photoshop?
> 

> article doesn't mention these two, but I use them for resizing, and I've 
> wondered about this issue.


I don't know, but I preferably use Ive's IC for resizing.


-- 
Thomas

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I have been working on this one:

https://github.com/mjhorvath/POVRay-Updated-Screen-Inc

It modifies the original to work with orthographic camera too.

It also can report the 2D screen coordinates of a 3D point.



Mike

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On 3/7/2021 2:41 AM, Thomas de Groot wrote:
> I have learned by experience that writing instructions for everybody's 
> use (or for a dedicated group like in a working environment) is one of 
> the most challenging things to do, especially if you intend them to be 
> 'clear', 'consistent', 'comprehensible'. It is a humbling experience 
> too, about your own limitations. More often than not I got people coming 
> to me telling me that my instructions 'didn't work', 'crashed the 
> system', 'were Russian to them', etc... I learned to integrate those 
> reactions into comprehensive updates. :-)
> 
> Btw, I am still 'digesting' but I'll come back to the topic.
> 

I enjoy writing documentation, wiki articles, tables and charts, etc.

I almost NEVER comment my code however.

Meh.

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Op 13/05/2021 om 06:27 schreef Mike Horvath:
> On 3/7/2021 2:41 AM, Thomas de Groot wrote:
>> I have learned by experience that writing instructions for everybody's 
>> use (or for a dedicated group like in a working environment) is one of 
>> the most challenging things to do, especially if you intend them to be 
>> 'clear', 'consistent', 'comprehensible'. It is a humbling experience 
>> too, about your own limitations. More often than not I got people 
>> coming to me telling me that my instructions 'didn't work', 'crashed 
>> the system', 'were Russian to them', etc... I learned to integrate 
>> those reactions into comprehensive updates. :-)
>>
>> Btw, I am still 'digesting' but I'll come back to the topic.
>>
> 
> I enjoy writing documentation, wiki articles, tables and charts, etc.
> 
Oh, I certainly agree with that! However, it does not come easy and 
needs a lot of corrections and rewriting before it is even basically 
acceptable to me. An extra challenge is to do it in English which is not 
my native language (which does not make writing in my /native/ languages 
any easier though).

> I almost NEVER comment my code however.
> 
I almost ALWAYS do. ;-)

-- 
Thomas

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Op 13/05/2021 om 05:15 schreef Mike Horvath:
> I have been working on this one:
> 
> https://github.com/mjhorvath/POVRay-Updated-Screen-Inc
> 
> It modifies the original to work with orthographic camera too.
> 
> It also can report the 2D screen coordinates of a 3D point.
> 
Yes, that is an important one. I have it here.

-- 
Thomas

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