Re: [Lcms-user] white point CIE E

[Marti M. <ma...@li...>]

Hi,

CIE Illuminant E (Equal energy) has XYZ of (100, 100, 100)
or chromaticity of xyY = (1/3, 1/3, 1). If you use (0.3, 0.3, 1)
instead of (0.333.., 0.333..., 1) this means an XYZ 
of (100, 100, 133.33..) which can cause the yellow cast. 
In photoshop there is a profile CIERGB.icc that is already 
using such white point. Great for testing.

Regards,
Marti.



----- Original Message ----- 
From: "Kai-Uwe Behrmann" <ku...@gm...>
To: "Lcms Liste" <lcm...@li...>
Sent: Friday, August 13, 2004 9:55 AM
Subject: [Lcms-user] white point CIE E


Hi,

CinePaint can handle Greg Wards LOGLuv encoded style of tiff images.
As it has now lcms inside, I want to set an suitable profile for display
the XYZ data.
Now in lcms all is handled,according to ICC, on an whitepoint of D50. The
difference to LOGLuv is it uses an DE equal energy (xy 0.3,0.3) white
point.
It seems it has some advantages to use DE for image processing. just I
can only display the images with an bluish cast, which is not desireable.

I created an profile with an DE whitepoint.
My test was to set an xyY triple with {0.3,0.3,1.0} and transform it to
XYZ resulting in {1.0,1.0,1.3} and set the XYZ values as the media
whitepoint.
Only rendering with absolute intent showed me an warm cast not neutral.
It is a bit too much of compensation. Why does it not work as expected?

Can I build an profile this way from XYZ wit DE to XYZ with D50, to
characterise the data for lcms?


kind regards

Kai-Uwe Behrmann
                                + imaging developer / panoramas
                                + color management
                                + email :ku...@gm...




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