How to implement Value Suppressing Colormaps in Makie

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I shared this recipe some time ago, maybe this capability should be added to Makie.jl directly?..
Basically, image() but alpha can be an array of values:

image
image1710×1948 148 KB

@recipe ImageAlpha (
		x::Makie.EndPoints,
		y::Makie.EndPoints,
		image::AbstractMatrix{<:Number}) begin
	Makie.MakieCore.documented_attributes(Makie.Image)...
	alpha = nothing
	alpharange = 0..1
end

function Makie.plot!(p::ImageAlpha)
	alpha = p.alpha[]
	p.alpha = 1
	Makie.color_and_colormap!(p, p.image)
	imcolors = @lift Makie.to_color($(p.calculated_colors))
	alphas_interval = @lift @something(extrema($(p.alpharange)), extrema(alpha))
	alpha = @lift clamp.((alpha .- $alphas_interval[1]) ./ ($alphas_interval[2] - $alphas_interval[1]), 0, 1)
	imcolors_a = @lift Makie.coloralpha.($imcolors, $alpha)
	image!(p, Makie.shared_attributes(p, Image), imcolors_a)
	return p
end

Makie.convert_arguments(::Type{<:ImageAlpha}, args...) = Makie.convert_arguments(ImageLike(), args...)