Re: colorsync-users Digest, Vol 19, Issue 45
Re: colorsync-users Digest, Vol 19, Issue 45
- Subject: Re: colorsync-users Digest, Vol 19, Issue 45
- From: Jeff Nova via colorsync-users <email@hidden>
- Date: Tue, 8 Nov 2022 12:09:53 -0800
Thank you, Graeme!! Your generosity in sharing your knowledge is inspiring
(and to be reflected! ; )
Yours,
Jeff
Jeff Nova
Chief Executive Officer
Colorhythm
https://colorhythm.com
Mobile: +1 510-710-9590
Main: +1 415-399-9921
On Sun, Nov 6, 2022 at 12:00 PM <email@hidden>
wrote:
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> Today's Topics:
>
> 1. Re: Normalizing CIEXYZ Values (WAYNE BRETL)
> 2. Re: Normalizing CIEXYZ Values (Jeff Nova)
> 3. FW: Normalizing CIEXYZ Values (email@hidden)
> 4. Re: Normalizing CIEXYZ Values (Jeff Nova)
> 5. Re: Normalizing CIEXYZ Values (Graeme Gill)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Sat, 05 Nov 2022 12:41:59 -0700 (MST)
> From: WAYNE BRETL <email@hidden>
> To: Jeff Nova <email@hidden>, Jeff Nova via colorsync-users
> <email@hidden>
> Subject: Re: Normalizing CIEXYZ Values
> Message-ID: <email@hidden>
> Content-Type: text/plain; charset=UTF-8
>
> "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
> > https://colorhythm.com
> > Mobile: +1 510-710-9590
> > Main: +1 415-399-9921
> > _______________________________________________
> > Do not post admin requests to the list. They will be ignored.
> > colorsync-users mailing list (email@hidden)
> > Help/Unsubscribe/Update your Subscription:
> >
> >
> > This email sent to email@hidden
>
>
> ------------------------------
>
> Message: 2
> Date: Sat, 5 Nov 2022 14:17:36 -0700
> From: Jeff Nova <email@hidden>
> To: WAYNE BRETL <email@hidden>
> Cc: Jeff Nova via colorsync-users <email@hidden>
> Subject: Re: Normalizing CIEXYZ Values
> Message-ID: <email@hidden>
> Content-Type: text/plain; charset=utf-8
>
> 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
> >> https://colorhythm.com
> >> Mobile: +1 510-710-9590
> >> Main: +1 415-399-9921
> >> _______________________________________________
> >> Do not post admin requests to the list. They will be ignored.
> >> colorsync-users mailing list (email@hidden)
> >> Help/Unsubscribe/Update your Subscription:
> >>
> >>
> >> This email sent to email@hidden
>
>
> ------------------------------
>
> Message: 3
> Date: Sat, 05 Nov 2022 14:33:16 -0700
> From: email@hidden
> To: email@hidden
> Subject: FW: Normalizing CIEXYZ Values
> Message-ID: <005101d8f15e$38e1eda0$aaa5c8e0$@cox.net>
> Content-Type: text/plain; charset=UTF-8
>
>
>
> -----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
> >> https://colorhythm.com
> >> Mobile: +1 510-710-9590
> >> Main: +1 415-399-9921
> >> _______________________________________________
> >> Do not post admin requests to the list. They will be ignored.
> >> colorsync-users mailing list (email@hidden)
> >> Help/Unsubscribe/Update your Subscription:
> >> cox.net
> >>
> >> This email sent to email@hidden
>
>
>
> ------------------------------
>
> Message: 4
> Date: Sat, 5 Nov 2022 20:28:26 -0700
> From: Jeff Nova <email@hidden>
> To: WAYNE BRETL <email@hidden>
> Cc: Jeff Nova via colorsync-users <email@hidden>
> Subject: Re: Normalizing CIEXYZ Values
> Message-ID:
> <
> email@hidden>
> Content-Type: text/plain; charset="UTF-8"
>
> Regarding the larger question...
>
> Inside an ICC profile, for example, the PCS illuminant if XYZ is formatted
> as such:
>
> XYZ 0.9642 1 0.82491
>
> while as I shared, the illuminant of viewing condition is like the
> example,19.6445 20.3718 16.8089
>
> I would think that the first example has been normalized with the largest
> number = 1?
>
> - Jeff
>
>
>
>
> Jeff Nova
> Chief Executive Officer
>
> Colorhythm
> https://colorhythm.com
> Mobile: +1 510-710-9590
> Main: +1 415-399-9921
>
>
> On Sat, 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
> > > https://colorhythm.com
> > > Mobile: +1 510-710-9590
> > > Main: +1 415-399-9921
> > > _______________________________________________
> > > Do not post admin requests to the list. They will be ignored.
> > > colorsync-users mailing list (email@hidden)
> > > Help/Unsubscribe/Update your Subscription:
> > >
> >
> > >
> > > This email sent to email@hidden
> >
>
>
> ------------------------------
>
> Message: 5
> Date: Sun, 06 Nov 2022 17:54:32 +1100
> From: Graeme Gill <email@hidden>
> To: ColorSync <email@hidden>
> Subject: Re: Normalizing CIEXYZ Values
> Message-ID: <email@hidden>
> Content-Type: text/plain; charset=UTF-8; format=flowed
>
> Jeff Nova via colorsync-users wrote:
>
> > 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.
>
> Hello Jeff,
> when dealing with reflective or transmissive media, it
> is usual to relate measurements to 100% reflectance or transmittance
> of the light source. Typically the instrument does this for you -
> it measures the reflected/transmitted spectrum then divides by the
> actual instrument 100% illuminant spectrum, then computes the resultant XYZ
> by integrating over an (by ICC convention) D50 light source.
> That light source XYZ value will have a Y value of 1.0 or 100%, meaning
> that the measured values will also cover this range.
>
> Within the ICC profile itself reflectance or transmittance XYZ values have
> a nominal range
> of 0..1, although it is convention in other file formats (such as CGATS)
> to use a % range
> of 0..100. Some measurements might exceed 100% due to fluorescence etc.
>
> Viewing conditions will typically remain in absolute XYZ terms so as to
> convey
> the absolute light level, but if only the chromaticity is of interest, you
> could
> divide the XYZ by the Y value.
>
> As noted by Wayne Bretl, xy chromaticity values don't typically require
> this normalization since it is taken care of by the very nature of the
> calculation.
>
> Cheers,
> Graeme Gill.
>
>
>
>
> ------------------------------
>
> Subject: Digest Footer
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> ------------------------------
>
> End of colorsync-users Digest, Vol 19, Issue 45
> ***********************************************
>
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