I received an email complaining that it was not true that as located on
the LCH color wheel, sRGB Blue was blatantly violet, sRGB Red was on the
orange side of red, sRGB Green was on the yellow side of green, and sRGB
Yellow as on the green side of yellow.
There is a sliver of truth in the complaint. On the LCH color wheel, my
statement is true.
However, LAB/LCH was designed to measure color differences, not to serve
as a color appearance model, even though it often gets used as such.
Also the LAB color space is particularly bad when it comes to dealing
with blues and violets.
For comparison, here are JCH and LCH values reported using the ArgyllCMS
sRGB Blue 301 [LCh]
sRGB Blue 273 [JCh] (still on the violet side of blue, but not
sRGB Green 134 [LCh]
sRGB Green 140 [JCh] (not as far towards yellow)
sRGB Red 41 [LCh]
sRGB Red 32 [JCh] (not as far towards orange)
sRGB Yellow 100 [LCh]
sRGB Yellow 111 [JCh] (farther towards green)
As you can see from these values, according to JCH model, sRGB Blue is
still on the violet side of the JCH color wheel. But it's not nearly as
far on the violet side of the JCH color wheel as it is on the LCH color
For both color wheels, sRGB Green is on the yellow side of green, sRGB
Red is on the orange side of red, and sRGB Yellow is on the green side
If you would like to check for yourself:
Here's the handprint.com CIECAM (JCH) color wheel:
Here's the handprint.com CIELAB (LCH) color wheel:
Here's the xicclu commands for checking the LCH/JCH values for sRGB
colors using an sRGB ICC profile:
xicclu -ir -pJ sRGB-elle-V2-g10.icc
xicclu -ir -pL sRGB-elle-V2-g10.icc
Here's a link to the xicclu documentation:
Here's a link to download ICC profiles:
It would be very nice if GIMP users had a way to pick colors using the
LCH color wheel or better yet the JCH color wheel. Either color space is
a vast improvement over the pathetically inadequate HSV.
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