Hi Shane,
The variables are based on the reference sample so I was hoping to determine
the formula for the entire sheet based on the reference. The spread sheet so
far has the reference and then the samples tested L, a and b. Here are the
fist few lines.
L a b
Master LT 28.63 2.04 4.08 28.99
Color 303 DARK BRONZE
Check L a b Delta E
1 1st 26.09 2.6 5.83 26.86
2nd 25.94 2.52 5.61 26.66
3rd 26.16 2.38 5.33 26.80
I was thinking it might be best to write a formula first for the h based on
the master data to determine which formula to use below. The formula for h is
the tangent to the -1 of (b/a) (this b and a are of the master reading). I
have no idea how to write this formula in excel.
Then from this I was hoping to be able to determine what T formula to use.
S sub L is also based on the L value of the master sample.
This website breaks down the formula really well but I just do not know how
to do these functions in excel (for example tan and cos and to the -1 power)
www.brucelindbloom.com/Eqn_DeltaE_CMC.html
Thank you so much,
Michelle
"Shane Devenshire" wrote:
Hi,
are DL, ISL, DC, ab, cSC, DH, SH and so on variables? Or is ab a*b for
example? The reason I ask is you have "unless h is between 164 and 345
degrees" but the only h you have is part of DH, SH, or hab.
How are all the variables laid out in the spreadsheet. Show us something,
A
1 SL
2 L
3 hab
4 ab
5 cSC
...
--
If this helps, please click the Yes button.
Cheers,
Shane Devenshire
"Michelle7890" wrote:
Does anyone out there have the Delta E cmc formula for excel? I am trying to
set up a spreadsheet that compares colors of test samples to a reference
sample in a spreadsheet. But my excel skills are not this good.
Thanks,
Michelle
CMC = [(DL* / lSL)^2 + (DC*ab / cSC)^2 + (DH*ab / SH)^2]^0.5
whe
SL = 0.040975L* / (1+0.01765L*) unless L < 16 when SL = 0.511
SC = 0.0638C*ab / (1+0.0131C*ab) + 0.638
SH = (fT + 1 - f)SC
whe
f = [(C*ab)^4 / {(C*ab)^4 + 1900)}]^0.5
T = 0.36 + |0.4 cos(hab + 35)|
unless h is between 164 and 345 degrees when
T = 0.56 + |0.2 cos(hab + 168)|