Merge pull request #43 from JuliaImages/teh/gaussian_width0

Fix KernelFactors.gaussian for sigma = 0
JuliaImages · Nov 5, 2017 · f9195cc · f9195cc
2 parents d7328d0 + 3bd42d5
commit f9195cc
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diff --git a/src/kernelfactors.jl b/src/kernelfactors.jl
@@ -267,7 +267,7 @@ in each direction from the center. `l` must be odd.
 function gaussian(σ::Real, l = 4*ceil(Int,σ)+1)
     isodd(l) || throw(ArgumentError("length must be odd"))
     w = l>>1
-    g = [exp(-x^2/(2*σ^2)) for x=-w:w]
+    g = σ == 0 ? [exp(0/(2*oftype(σ, 1)^2))] : [exp(-x^2/(2*σ^2)) for x=-w:w]
     centered(g/sum(g))
 end
 

diff --git a/test/specialty.jl b/test/specialty.jl
@@ -179,6 +179,9 @@ using Base.Test
         for k = (Kernel.gaussian((2,3)), Kernel.gaussian([2,3]), Kernel.gaussian([2,3], [9,7]))
             @test sum(k) ≈ 1
         end
+        # Bug noticed in Images issue #674
+        k = KernelFactors.gaussian((3, 3, 0))
+        @test k[3].data == OffsetArray([1.0], 0:0)
     end
 
     @testset "DoG" begin