Re: [Matplotlib-users] overlay of images

[John H. <jdh...@ac...>]

>>>>> "Teemu" == Teemu Rinne <Tee...@he...> writes:


    Teemu> How to do this?  Do I have to combine the RGB values of the
    Teemu> two images 'manually'?

Basically what you are talking about is adding an alpha channel to the
color map, and setting it to be transparent for image values less than
a certain value.  Perry Greenfield is the colormap implementer and
resident expert.

Perry -- how hard would it be to either subclass or extend the current
framework to include an alpha channel?  I think it could be done in
just a few lines of code actually.  Eg, something like

   self._alpha_lut  = makeMappingArray(self.N,
                     self._segmentdata.get('blue', [1.0, 1.0]) 

and then modifying

    def __call__(self, X, alpha=1.0):

to deal with it.  

Perry do you have time to take a crack at this?  I think this would be
very useful.

Thanks,
JDH