Merge pull request #711 from zygmuntszpak/fix_adjust_gamma

Fixes adjust_gamma so that it works on offset arrays

src/exposure.jl

@@ -371,21 +371,24 @@ adjust_gamma(img::AbstractArray{T}, gamma::Number) where {T<:Number} = _adjust_g
 adjust_gamma(img::AbstractArray{T}, gamma::Number) where {T<:Colorant} = _adjust_gamma(img, gamma, T)
 
 function _adjust_gamma(img::AbstractArray, gamma::Number, C::Type)
-    gamma_corrected_img = zeros(C, size(img))
+    gamma_corrected_img = _fill(oneunit(C), indices(img))
     for I in eachindex(img)
         gamma_corrected_img[I] = _gamma_pixel_rescale(img[I], gamma)
     end
     gamma_corrected_img
 end
 
 function adjust_gamma(img::AbstractArray{T}, gamma::Number, minval::Number, maxval::Number) where T<:Number
-    gamma_corrected_img = zeros(Float64, size(img))
+    gamma_corrected_img = _fill(oneunit(T), indices(img))
     for I in eachindex(img)
         gamma_corrected_img[I] = _gamma_pixel_rescale(img[I], gamma, minval, maxval)
     end
     gamma_corrected_img
 end
 
+_fill(val, dim) = fill(val, dim) # fallback
+_fill(val, dim::NTuple{N,Base.OneTo}) where {N} = fill(val, map(length, dim))
+
 """
 ```
 hist_matched_img = histmatch(img, oimg, nbins)

test/exposure.jl

@@ -125,39 +125,79 @@ using Base.Test, Images, Colors, FixedPointNumbers
         @test img == ret
         @test eltype(ret) == eltype(img)
 
+        imgp = padarray(img, Fill(0, (2,2)))
+        retp = adjust_gamma(imgp, 1)
+        @test imgp == retp
+        @test eltype(retp) == eltype(imgp)
+
         img = oneunits(Gray{N0f8}, 10, 10)
         ret = adjust_gamma(img, 1)
         @test img == ret
         @test eltype(ret) == eltype(img)
 
+        imgp = padarray(img, Fill(0, (2,2)))
+        retp = adjust_gamma(imgp, 1)
+        @test imgp == retp
+        @test eltype(retp) == eltype(imgp)
+
         img = oneunits(Gray{N0f16}, 10, 10)
         ret = adjust_gamma(img, 1)
         @test eltype(ret) == eltype(img)
 
+        imgp = padarray(img, Fill(0, (2,2)))
+        retp = adjust_gamma(imgp, 1)
+        @test imgp == retp
+        @test eltype(retp) == eltype(imgp)
+
         img = oneunits(AGray{N0f8}, 10, 10)
         ret = adjust_gamma(img, 1)
         @test img == ret
         @test eltype(ret) == eltype(img)
 
+        imgp = padarray(img, Fill(0, (2,2)))
+        retp = adjust_gamma(imgp, 1)
+        @test imgp == retp
+        @test eltype(retp) == eltype(imgp)
+
         img = oneunits(RGB{N0f8}, 10, 10)
         ret = adjust_gamma(img, 1)
         @test img == ret
         @test eltype(ret) == eltype(img)
 
+        imgp = padarray(img, Fill(zero(eltype(img)), (2,2)))
+        retp = adjust_gamma(imgp, 1)
+        @test imgp == retp
+        @test eltype(retp) == eltype(imgp)
+
         img = oneunits(RGB{N0f16}, 10, 10)
         ret = adjust_gamma(img, 1)
         @test img == ret
         @test eltype(ret) == eltype(img)
 
+        imgp = padarray(img, Fill(zero(eltype(img)), (2,2)))
+        retp = adjust_gamma(imgp, 1)
+        @test imgp == retp
+        @test eltype(retp) == eltype(imgp)
+
         img = oneunits(RGB{Float64}, 10, 10)
         ret = adjust_gamma(img, 1)
         @test all(map((i, r) -> isapprox(i, r), img, ret))
         @test eltype(ret) == eltype(img)
 
+        imgp = padarray(img, Fill(zero(eltype(img)), (2,2)))
+        retp = adjust_gamma(imgp, 1)
+        @test all(map((i, r) -> isapprox(i, r), imgp, retp))
+        @test eltype(retp) == eltype(imgp)
+
         img = oneunits(ARGB{N0f8}, 10, 10)
         ret = adjust_gamma(img, 1)
         @test img == ret
 
+        imgp = padarray(img, Fill(zero(eltype(img)), (2,2)))
+        retp = adjust_gamma(imgp, 1)
+        @test imgp == retp
+
+
         #Working
 
         img = reshape(1:1:100, 10, 10)
@@ -361,7 +401,7 @@ using Base.Test, Images, Colors, FixedPointNumbers
         @test complement(Gray(0.2)) == Gray(0.8)
         @test all(complement.(img) .== 1 - img)
         # deprecated (#690)
-        @test all(complement(img) .== 1 - img)
+        @test all(complement.(img) .== 1 - img)
 
         hist = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]