|
Hi,
This is more or less the algorithm littlecms is
using for gamut checking.
The differences would be, I'm using relative
colorimetric instead and the "Lab2" value is checked again across the profile to
track white point displacements, but the basics are same.
It works to me. If anybody knows a better method,
and want to share it, I would be glad to include it in the CMM.
Hue is an angle, so the range goes 0-360. Chroma
can be any positive number.
Regards,
----- Original Message -----
Sent: Thursday, March 25, 2004 11:56
AM
Subject: [Lcms-user] Gamut Checking for
creating colour charts
Im in the process of creating some custom colour
charts for work, Theis is be based on LCH. I dont want to print all the
colours in the LCH colourspace as this is too many and most are out of
gamut (3600 colours at 360 step 10 and L/C step
0.1) I want to limit the range to
colours inside the gamut of the device. I have working code based on
the below steps but I just want to check if this is the correct
way
Firstly im converting from LCH to D50 LAB and
calling this LAB1
Then im Converting from LAB1 to Device Colours
via Absolute Colourmetric transform, Im then
taking this Device Colour and converting it back from the Device colour
via Absolute Colourmetric transform and calling this LAB2.
Im then discarding all colours where the Delta E
between LAB1 and LAB2 > 20 (The ensures im getting colours just outside the
gamut)
Is this the best way?
Oh BTW is the range for Chroma and Hue H
0.0 to 1.0?
| 