colorscale=- results in a black image

[aplavin]

Result of image(randn(20, 20), colorscale=-) is just an empty black image:

I would expect the same visual result as image(-A), with the only difference being labels for the colorbar.

• what version of Makie are you running? (]st -m Makie) latest, v0.22.2
• can you reproduce the bug with a fresh environment ? (]activate --temp; add Makie) yes
• What platform + GPU are you on? any

[SimonDanisch]

Huh, I guess the colornorm needs to get sorted after applying the colorscale:

julia> f, ax, pl = image(randn(20, 20), colorscale=-)
julia> s = display(f)
julia> robj = GLMakie.plot2robjs(s, pl)[1]
julia> robj[:color_norm][]
2-element Vec{2, Float32} with indices SOneTo(2):
  2.4661164
 -2.9072657
julia> robj[:color_norm][] = Vec2f(-3, 3)

[asinghvi17]

Looks like this is an issue on CairoMakie as well:

[SimonDanisch]

Yeah, the code for this is in Makie.jl

[SimonDanisch]

It's here: https://github.com/MakieOrg/Makie.jl/blob/master/src/colorsampler.jl#L309-L311

[asinghvi17]

Thanks for the hint, added some calls to extrema (maybe that should be distinct_extrema_nan?) in #4884