Hi Gary,
The script in question is part of the standard Ferret distribution:
GO exact_colors #_of_colors [input_spectrum]
[output_filename]
- Steve
================================
Steve Hankin wrote:
Hi Gary,
There are a number of aspects to this question. I interpret your main
question to be how to know the particular RGB values that Ferret is
using for each color level in the color key of a given plot. The
palette file defines a piecewise linear path through color space; now
how to get the actual colors used in a particular plot. It isn't hard
to get these RGB triple values. I had some scripts around, but *many*
years ago and I cannot find them now. But have outlined the algorithm
below. I know of no tool to generate color names like "light
green-blue", though one could create it ... even as a Ferret script.
To get the RGB triples just follow these steps
- tell Ferret to read the spk file (the palette file) as if it
were
a data file
- read the percentage field (column 10 in the first pass, and
create an axis from it; and a grid from that
- read the r,g,b values onto this axis
The RGB values from the palette file are now defined as variables
(Rval, Gval, Bval) on an axis that goes from 0 to 1.
- Regrid them onto a regularly-spaced axis that has the number of
color levels on your plot. E.g.
DEFINE AXIS/X=0:1/npoints=40 x40 ! if there are 39 color levels
LIST Rval[gx=x40], Gval[gx=x40], Bval[gx=x40]
Maybe this is of some help ....
- Steve
=====================
Gary Strand wrote:
Does ferret have a means to list the levels and colors used in a
color-filled contour plot, given:
fill/lev="(-6000,-1000,1000)(-1000,-100,100)(-100,100,10)(100,1000,100)(1000,6000,1000)"/pal=topo
elev
with an accompanying color specification:
! Palette for
ocean/terrestrial elevation.
! *jc* 11/00
RGB_Mapping By_Value
! Val R G B
-8000. 0. 0.
10. ! blue-black
-4000. 0. 0. 50.
-2000. 0. 0.
100. ! blue
-300. 40. 70.
100.
-100. 50. 100. 100.
-50. 40. 80. 70.
-0.1 90. 100.
100. ! light green-blue
0. 0. 20.
00. ! dark green
100. 0. 70.
30. ! light green
300. 90. 100.
0. ! light yellow
1200. 60. 30.
0. ! rust
4000. 90. 90.
100. ! ice blue
5000. 100. 100.
100. ! white
I'm aware of 'ppl list levels', which will give the actual
levels used in the PLOT command, but is there a way to get at the RGB
triples associated with each level?
Thanks!
--
Steve Hankin, NOAA/PMEL -- Steven.C.Hankin@xxxxxxxx
7600 Sand Point Way NE, Seattle, WA 98115-0070
ph. (206) 526-6080, FAX (206) 526-6744
"The only thing necessary for the triumph of evil is for good men
to do nothing." -- Edmund Burke
--
Steve Hankin, NOAA/PMEL -- Steven.C.Hankin@xxxxxxxx
7600 Sand Point Way NE, Seattle, WA 98115-0070
ph. (206) 526-6080, FAX (206) 526-6744
"The only thing necessary for the triumph of evil is for good men
to do nothing." -- Edmund Burke
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