Should self._alpha_lut always copy the blue segment data
> (or are you showing what the user would have to do?) I
> would have guessed that it would default to being always 1
> (I think that's the intent above but how does one then
> define it independently outside of the class definition.
Uh, maybe I have the flu. I meant
self._alpha_lut = makeMappingArray(self.N,
self._segmentdata.get('alpha', [1.0, 1.0])
I'm not sure about the [1.0, 1.0] -- that's your job
What I'm trying to say is that we can use the dict get method to
default to the current behavior if the alpha channel is not defined in
> Secondly, this example asks for a threshold based on
> prenormalized data values (i.e., image value of 30). To get
> what the user wants, the user must either define the alpha
> map to match the normalized value of 30 or normalize the
> data to match 30 to the alpha map threshold. It's not so
> obvious to me how this is best handled. A fancier
> normalization function that uses data-based thresholds to
> map to color map thresholds? Otherwise, it may be fairly
> painful to apply in practice. A convenient way to define a
> color map based on data values and how the data will be
I'll think about these issues -- gotta run now. But they are
orthogonal to having an alpha channel in the colormap, no?
Cheers -- hope you're feeling better!