Actually, it came up in a plotting context https://github.com/tbreloff/Plots.jl/issues/138 . The use case is to overlay colors on a world map where blue means colder than average and red means warmer than average. Of course, if there is not much difference from the average, you don't want it to be white, you want it to be transparent, such that you can actually see the map. Thanks for pointing me towards the discussion in ColorTypes.jl
On Friday, February 12, 2016 at 11:19:28 AM UTC+1, Andreas Lobinger wrote: > > In the discussions about ColorTypes it showed up, that the majority > prefered color independent of opacity. I'd guess you need to get the > colormap via Colors.jl and then add the opacity information (created by > linscale etc.). But i'm not sure that applying a color defined as > color+transparency (RGBA etc.) is clearly defined in all cases. At least in > plotting/rendering using RGB is prevalent. > > On Friday, February 12, 2016 at 10:48:06 AM UTC+1, Patrick Kofod Mogensen > wrote: >> >> Is it possible to create a colormap as described in the title using >> Colors.jl? I couldn't seem to find anything on Colormaps and >> transparency/opacity. >> >> Best, >> Patrick >> >
