Merge pull request #20 from JuliaImages/teh/widening

Widen all-Integer eltypes. Fixes #17.

.travis.yml

@@ -9,11 +9,9 @@ julia:
 notifications:
   email: false
 # uncomment the following lines to override the default test script
-script:
- - if [[ -a .git/shallow ]]; then git fetch --unshallow; fi
- # For the time being, clone unregistered packages
- - julia -e 'Pkg.clone("https://github.com/JuliaImages/ImageCore.jl")'
- - julia -e 'Pkg.clone(pwd()); Pkg.build("ImageFiltering"); Pkg.test("ImageFiltering"; coverage=true)'
+# script:
+#  - if [[ -a .git/shallow ]]; then git fetch --unshallow; fi
+#  - julia -e 'Pkg.clone(pwd()); Pkg.build("ImageFiltering"); Pkg.test("ImageFiltering"; coverage=true)'
 after_success:
   # push coverage results to Codecov
   - julia -e 'cd(Pkg.dir("ImageFiltering")); Pkg.add("Coverage"); using Coverage; Codecov.submit(Codecov.process_folder())'

src/imfilter.jl

@@ -972,6 +972,8 @@ end
 filter_type{S}(img::AbstractArray{S}, kernel) = filter_type(S, kernel)
 
 filter_type{S,T}(::Type{S}, kernel::ArrayLike{T}) = typeof(zero(S)*zero(T) + zero(S)*zero(T))
+filter_type{S<:Integer,T<:Integer}(::Type{S}, kernel::ArrayLike{T}) =
+    typeof(zero(widen(S))*zero(widen(T)) + zero(widen(S))*zero(widen(T)))
 filter_type{S<:Union{Normed,FixedColorant}}(::Type{S}, ::Laplacian) = float32(S)
 filter_type{S<:Colorant}(::Type{S}, kernel::Laplacian) = S
 filter_type{S<:AbstractFloat}(::Type{S}, ::Laplacian) = S
@@ -982,6 +984,7 @@ filter_type(::Type{Bool}, ::Laplacian) = Int8
 signed_type(::Type{UInt8})  = Int16
 signed_type(::Type{UInt16}) = Int32
 signed_type(::Type{UInt32}) = Int64
+signed_type{T<:Integer}(::Type{T}) = Int
 
 @inline function filter_type{S}(::Type{S}, kernel::Tuple{Any,Vararg{Any}})
     T = filter_type(S, kernel[1])

test/nd.jl

@@ -36,6 +36,13 @@ using Base.Test
     @test imfilter!(r, out, img, (kern,), "replicate") == imgf
     @test_throws MethodError imfilter!(r, out, img, (kern,), "replicate", Algorithm.FIR())
 
+    # Element-type widening
+    v = fill(0xff, 10)
+    kern = centered(fill(0xff, 3))
+    vout = imfilter(v, kern)
+    @test eltype(vout) == UInt32
+    @test all(x->x==0x0002fa03, vout)
+
     # Cascades don't result in out-of-bounds values
     k1 = centered([0.25, 0.5, 0.25])
     k2 = OffsetArray([0.5, 0.5], 1:2)
@@ -62,6 +69,12 @@ using Base.Test
     @test out ≈ imfilter(img, kern)
 end
 
+@testset "2d widening" begin
+    ret = imfilter(fill(typemax(Int16), 10, 10), centered(Int16[1 2 2 2 1]))  # issue #17
+    @test eltype(ret) == Int32
+    @test all(x->x==262136, ret)
+end
+
 @testset "3d" begin
     img = trues(10,10,10)
     kernel = centered(trues(3,3,3)/27)