FW: Normalizing CIEXYZ Values
FW: Normalizing CIEXYZ Values
- Subject: FW: Normalizing CIEXYZ Values
- From: "Wayne E. Bretl via colorsync-users" <email@hidden>
- Date: Sat, 05 Nov 2022 14:33:16 -0700
-----Original Message-----
From: email@hidden <email@hidden>
Sent: Saturday, November 5, 2022 2:29 PM
To: 'Jeff Nova' <email@hidden>
Subject: RE: Normalizing CIEXYZ Values
If you are trying to do a chromatic adaptation transform, I will let someone
else answer, as I would probably get it wrong somewhere.
Here's a Wikipedia intro:
https://en.wikipedia.org/wiki/Chromatic_adaptation#CIE_color_appearance_models
-----Original Message-----
From: Jeff Nova <email@hidden>
Sent: Saturday, November 5, 2022 2:18 PM
To: WAYNE BRETL <email@hidden>
Cc: Jeff Nova via colorsync-users <email@hidden>
Subject: Re: Normalizing CIEXYZ Values
Hi Wayne!
Thank you for sharing your insight. I suppose I am trying to understand the ICC
spec when it presents XYZ values “un-normalized” vs “normalized.” Putting
aside the xy conversion … or is this what is meant? I’ll need to look at the
spec again (and again and again…).
Jeff
> On Nov 5, 2022, at 12:42 PM, WAYNE BRETL <email@hidden> wrote:
>
> "normalizing to [0,1] first" does not make sense to me.
> When you calculate the (lower case) x,y for the chromaticity plot, the values
> are automatically between 0 and 1.
>
> x = (X)/(X+Y+Z)
> y = (Y)/(X+Y+Z)
>
>> On November 5, 2022 at 11:46 AM Jeff Nova via colorsync-users
>> <email@hidden> wrote:
>>
>>
>> Hello my colorful friends! I pray you are doing well.
>>
>> I have a math question for you. I would like to display the viewing
>> conditions' illuminant and surround on a 1931 2deg chromaticity plot.
>> These are un-normalized CIEXYZ values that need to be normalized
>> within the plot range (0-1 both axes) first.
>>
>> Example:
>>
>> sRGB IEC 2.1 profile:
>>
>> Illuminant - 19.6445 20.3718 16.8089
>>
>> Surround - 3.92889 4.07439 3.36179
>>
>> How to normalize them? Please forgive my ignorance; I am learning
>> every day.
>>
>> I thank you in advance for any support you might be able to provide.
>> : )
>>
>> Jeff
>>
>>
>> Jeff Nova
>> Chief Executive Officer
>>
>> Colorhythm
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