Hi Chuck,
(Re-sending my earlier answer with [ferret_users] in the subject line
so it will be sorted properly into the right thread in the archive).
There are a couple of issues here. Maybe you just didn't show it here
but you need this line at the start of the palette file.
RGB_Mapping By_Value
But what you're asking about I think has to do with the labeling of the
color keys. This may be done differently from what you expect. Instead
of labeling the color, the labels are for the line between colors.
So, defining a simple variable with the right range,
yes? let var = (i*j) - 12
yes? ! Here zero is at the bottom of the white color
yes? shade/i=1:4/j=1:6/pal=white_centered_values var
yes? ! Here there are two cells colored in white, centered at
zero.
yes?
shade/i=1:4/j=1:6/pal=white_centered_values/lev=(-12,10.,0.5) var
yes? ! Or try this
yes?
shade/i=1:4/j=1:6/pal=white_centered_values/lev=(-12.5,10.5,1) var
Ansley
Charles Seman wrote:
Dear
ferret users,
I have a question about making and using a color palette using
"RGB_Mapping By_Value" for plotting bias values such that there is
color white within a range surrounding zero bias and rainbow-like
colors by value outside of this range. With a color palette using a
single "0" level for white and contour levels [-.25,.25] the plot shows
no white, but by "shifting" the color palette to a "negative" bias (as
shown here below), we get a white area as desired between [-.25,.25]...
Does the "interpolation" for shading between contour levels [-.25,.25]
use the "lower" palette interval limit in question for the
interpolation? so that for [-.25,.25], -0.25 is used? That is, are
the RGB values for [-0.5,0.0] in the table used to interpolate to
-0.25, and then the resulting RGB triplet used for specifying the
(white) color for the [-.25,.25] interval?
!----------------------
! Val R G B
!----------------------
-12.0 0. 100. 100.
-5.0 20. 20. 100.
-2.0 60. 60. 100.
-0.5 100. 100. 100.
0.0 100. 100. 100.
1.0 100. 60. 60.
3.0 100. 20. 20.
10.0 100. 100. 0.
Thanks for your help with this,
Chuck
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