From 26d940a20c24eccedf368fe890be3d37e167c0ed Mon Sep 17 00:00:00 2001
From: Ioannis Valasakis <code@wizofe.uk>
Date: Sat, 7 Mar 2020 20:52:54 +0000
Subject: [PATCH 1/2] Add var, std, complement. Migrated from Images.jl

---
 src/ColorVectorSpace.jl | 32 +++++++++++++++++++++++++++++++-
 1 file changed, 31 insertions(+), 1 deletion(-)

diff --git a/src/ColorVectorSpace.jl b/src/ColorVectorSpace.jl
index 3a97e50..16822ab 100644
--- a/src/ColorVectorSpace.jl
+++ b/src/ColorVectorSpace.jl
@@ -10,7 +10,7 @@ import Base: abs, abs2, clamp, convert, copy, div, eps, isfinite, isinf,
 import LinearAlgebra: norm
 import StatsBase: histrange, varm
 import SpecialFunctions: gamma, lgamma, lfact
-import Statistics: middle
+import Statistics: middle, var, std
 
 export nan
 
@@ -207,6 +207,35 @@ for op in unaryOps
     @eval ($op)(c::AbstractGray) = $op(gray(c))
 end
 
+function var(A::AbstractArray{C}; kwargs...) where C<:AbstractGray
+    imgc = channelview(A)
+    base_colorant_type(C)(var(imgc; kwargs...))
+end
+
+function var(A::AbstractArray{C,N}; kwargs...) where {C<:Colorant,N}
+    imgc = channelview(A)
+    colons = ntuple(d->Colon(), Val(N))
+    inds1 = axes(imgc, 1)
+    val1 = var(view(imgc, first(inds1), colons...); kwargs...)
+    vals = similar(imgc, typeof(val1), inds1)
+    vals[1] = val1
+    for i in first(inds1)+1:last(inds1)
+        vals[i] = var(view(imgc, i, colons...); kwargs...)
+    end
+    base_colorant_type(C)(vals...)
+end
+
+"""
+    y = complement(x)
+
+Take the complement `1-x` of `x`.  If `x` is a color with an alpha channel,
+the alpha channel is left untouched. Don't forget to add a dot when `x` is
+an array: `complement.(x)`
+"""
+complement(x::Union{Number,Colorant}) = oneunit(x)-x
+complement(x::TransparentColor) = typeof(x)(complement(color(x)), alpha(x))
+
+std(A::AbstractArray{C}; kwargs...) where {C<:Colorant} = mapc(sqrt, var(A; kwargs...))
 middle(c::AbstractGray) = arith_colorant_type(c)(middle(gray(c)))
 middle(x::C, y::C) where {C<:AbstractGray} = arith_colorant_type(C)(middle(gray(x), gray(y)))
 
@@ -343,4 +372,5 @@ _precompile_()
 @deprecate (*)(A::AbstractArray{T}, b::TransparentGray) where {T<:Number} A.*b
 @deprecate (*)(b::TransparentGray, A::AbstractArray{T}) where {T<:Number} A.*b
 
+@deprecate complement(x::AbstractArray) complement.(x)
 end

From e6041e0449cbad2a6e280b789b5b654e650c260b Mon Sep 17 00:00:00 2001
From: Ioannis Valasakis <code@wizofe.uk>
Date: Sat, 7 Mar 2020 20:53:52 +0000
Subject: [PATCH 2/2] Add test for complement. Migrated from Images.jl

---
 test/runtests.jl | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/test/runtests.jl b/test/runtests.jl
index 8b8030e..210fef7 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -126,6 +126,13 @@ end
         @test Gray24(0.8)*0.5 === Gray(0.4)
         @test Gray24(0.8)/2   === Gray(0.5f0*N0f8(0.8))
         @test Gray24(0.8)/2.0 === Gray(0.4)
+
+        # Complement
+        @test complement(Gray(0.5)) == Gray(0.5)
+        @test complement(Gray(0.2)) == Gray(0.8)
+        @test all(complement.(img) .== 1 .- img)
+        # deprecated (#690)
+        @test all(complement.(img) .== 1 .- img)
     end
 
     @testset "Comparisons with Gray" begin
@@ -276,6 +283,14 @@ end
         @test RGB24(1,0,0)/2.0 === RGB(0.5,0,0)
     end
 
+    @testset "Complement" begin
+        @test complement.([Gray(0.2)]) == [Gray(0.8)]
+        @test complement.([Gray{N0f8}(0.2)]) == [Gray{N0f8}(0.8)]
+        @test complement.([RGB(0,0.3,1)]) == [RGB(1,0.7,0)]
+        @test complement.([RGBA(0,0.3,1,0.7)]) == [RGBA(1.0,0.7,0.0,0.7)]
+        @test complement.([RGBA{N0f8}(0,0.6,1,0.7)]) == [RGBA{N0f8}(1.0,0.4,0.0,0.7)]
+    end
+
     @testset "Arithemtic with RGBA" begin
         cf = RGBA{Float32}(0.1,0.2,0.3,0.4)
         @test @inferred(zero(cf)) === RGBA{Float32}(0,0,0,0)