On Wed, 22 Aug 2001, Jim Edwards wrote:
> Sets or retreves the chslice including the upper
and lower limits of
> the colortable. Data values outside this range are
ploted as missing
> - transparent black. setting low>= high results in
a set of
> reasonable limits being chosen for you.
A more common default for this sort of thing (in
other programs that I've
used) is that data values outside the given range are
plotted as the
maximum/minimum. This way, you can easily "saturate"
a variable to
prevent a strong peak somewhere from obscuring the
rest of the data.
Perhaps we should have a toggle between the two
methods. I like the missing method because I can
specify a colortable for a subset of the data range,
and ignore data outside that range. So for example if
I have relative humidity in my dataset I can set the
lower limit to 95% and just look at the air
approaching saturation or I can set the upper limit to
say 45% and just consider air which is extremely dry.
This, combined with use of the color alpha,
also makes combining more than one color filled image
on the same graph more readable.
Of course you can also do this with the maximum/minimum
method you suggest through a judicious choice of
colortables, in the first example my
minimum value alpha would be 0 and in the second my
maximum value alpha would be 0 - but that is more