POV-Ray: Newsgroups: povray.advanced-users: CIELUV

POV-Ray : Newsgroups : povray.advanced-users : CIELUV		Server Time 22 Dec 2024 12:32:33 EST (-0500)

From: Mike Horvath
Subject: CIELUV
Date: 5 Dec 2016 21:13:03
Message: <58461eaf$1@news.povray.org>

I'm looking at the formulas for CIELUV color space on Wikipedia.

https://en.wikipedia.org/wiki/CIELUV

The article says, "The quantities u′n and v′n are the (u′, v′) 
chromaticity coordinates of a "specified white object" – which may be 
termed the white point – and Yn is its luminance."

I have a D65 whitepoint:

     #declare XYZWhiteReference = color <95.047,100.000,108.883>;

Which of these values is u'n, v'n and Yn?

Mike

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From: Mike Horvath
Subject: Re: CIELUV
Date: 5 Dec 2016 21:30:02
Message: <584622aa@news.povray.org>

On 12/5/2016 9:13 PM, Mike Horvath wrote:
> I'm looking at the formulas for CIELUV color space on Wikipedia.
>
> https://en.wikipedia.org/wiki/CIELUV
>
> The article says, "The quantities u′n and v′n are the (u′, v′)
> chromaticity coordinates of a "specified white object" – which may be
> termed the white point – and Yn is its luminance."
>
> I have a D65 whitepoint:
>
>     #declare XYZWhiteReference = color <95.047,100.000,108.883>;
>
> Which of these values is u'n, v'n and Yn?
>
> Mike

Never mind. I will just use the code from ColorMine.org again.

Mike

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From: clipka
Subject: Re: CIELUV
Date: 5 Dec 2016 21:32:25
Message: <58462339$1@news.povray.org>

Am 06.12.2016 um 03:13 schrieb Mike Horvath:
> I'm looking at the formulas for CIELUV color space on Wikipedia.
> 
> https://en.wikipedia.org/wiki/CIELUV
> 
> The article says, "The quantities u′n and v′n are the (u′, v′)
> chromaticity coordinates of a "specified white object" – which may be
> termed the white point – and Yn is its luminance."
> 
> I have a D65 whitepoint:
> 
>     #declare XYZWhiteReference = color <95.047,100.000,108.883>;
> 
> Which of these values is u'n, v'n and Yn?

Neither. Those three values are X, Y and Z, respectively. The formula
for converting these to u' and v' are given a few lines later in the
Wikipedia article:

    u' = (4X) / (X + 15Y + 3Z)
    v' = (9Y) / (X + 15Y + 3Z)

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From: Mike Horvath
Subject: Re: CIELUV
Date: 5 Dec 2016 21:34:10
Message: <584623a2$1@news.povray.org>

On 12/5/2016 9:30 PM, Mike Horvath wrote:
> On 12/5/2016 9:13 PM, Mike Horvath wrote:
>> I'm looking at the formulas for CIELUV color space on Wikipedia.
>>
>> https://en.wikipedia.org/wiki/CIELUV
>>
>> The article says, "The quantities u′n and v′n are the (u′, v′)
>> chromaticity coordinates of a "specified white object" – which may be
>> termed the white point – and Yn is its luminance."
>>
>> I have a D65 whitepoint:
>>
>>     #declare XYZWhiteReference = color <95.047,100.000,108.883>;
>>
>> Which of these values is u'n, v'n and Yn?
>>
>> Mike
>
> Never mind. I will just use the code from ColorMine.org again.
>
> Mike

Link:

https://github.com/THEjoezack/ColorMine/blob/master/ColorMine/ColorSpaces/Conversions/LuvConverter.cs

Mike

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From: Mike Horvath
Subject: Re: CIELUV
Date: 5 Dec 2016 21:34:18
Message: <584623aa$1@news.povray.org>

On 12/5/2016 9:31 PM, clipka wrote:
> Am 06.12.2016 um 03:13 schrieb Mike Horvath:
>> I'm looking at the formulas for CIELUV color space on Wikipedia.
>>
>> https://en.wikipedia.org/wiki/CIELUV
>>
>> The article says, "The quantities u′n and v′n are the (u′, v′)
>> chromaticity coordinates of a "specified white object" – which may be
>> termed the white point – and Yn is its luminance."
>>
>> I have a D65 whitepoint:
>>
>>     #declare XYZWhiteReference = color <95.047,100.000,108.883>;
>>
>> Which of these values is u'n, v'n and Yn?
>
> Neither. Those three values are X, Y and Z, respectively. The formula
> for converting these to u' and v' are given a few lines later in the
> Wikipedia article:
>
>     u' = (4X) / (X + 15Y + 3Z)
>     v' = (9Y) / (X + 15Y + 3Z)
>

Thanks!

Mike

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