dependency on PyPlot and Images

[bjarthur]

seems like a nice package, and i'd like to use it, but the dependencies on PyPlot and Images are turning me away. why should generating colormaps require those packages? i can see how to use colormaps one might need Images, but there are so many alternatives to PyPlot (Gadfly, Winston, Makie, Plots), that to add that as a dependency really adds bloat to users who don't use PyPlot. would be great to have the core functionality split out so as not to depend on either of them.

[peterkovesi]

I agree with all your comments. Currently the package combines generation of colour maps, diagnostics and analysis of colour maps, and some specialised functions for rendering images with colour maps. These should be separated.

The use of PyPlot is merely historical. The development of the package started back at Julia 0.4. At the time PyPlot was perhaps the most comprehensive plotting package, in particular offering features that I used a lot in my work - 3D plotting, the ability to plot overlaying lines on images, and the ability to zoom and pan within very large images. It was the default package that I used for everything. Of course plotting in Julia has changed significantly since then.

I am now retired and now no longer find myself doing very much coding so these issues have not been high on my priority list. However, thank you for your comments it is good to get a bit of a nudge and I will endeavour to address some of these issues in due course but I cannot promise anything soon. In the meantime any pull requests are most welcome!

Cheers