-----Original Message----- From: waynebretl@cox.net <waynebretl@cox.net> Sent: Saturday, November 5, 2022 2:29 PM To: 'Jeff Nova' <jnova@colorhythm.com> 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_mode... -----Original Message----- From: Jeff Nova <jnova@colorhythm.com> Sent: Saturday, November 5, 2022 2:18 PM To: WAYNE BRETL <waynebretl@cox.net> Cc: Jeff Nova via colorsync-users <colorsync-users@lists.apple.com> 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 <waynebretl@cox.net> 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 <colorsync-users@lists.apple.com> 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
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