# HG changeset patch
# User Tuomo Valkonen <tuomov@iki.fi>
# Date 1576344393 -7200
# Node ID 0d99f8f7d26160824b08e42abb8a2960f73a9b03
# Parent  8ff7da7bc77dc4d7fa1c62c34afe0590d2cc6779
Added ImFilter & simple_imfilter.

diff -r 8ff7da7bc77d -r 0d99f8f7d261 Manifest.toml
--- a/Manifest.toml	Sat Dec 14 14:59:59 2019 +0200
+++ b/Manifest.toml	Sat Dec 14 19:26:33 2019 +0200
@@ -85,6 +85,11 @@
 [[Mmap]]
 uuid = "a63ad114-7e13-5084-954f-fe012c677804"
 
+[[OffsetArrays]]
+git-tree-sha1 = "27f32af4e7b11f5aa9f3cad60b777cd042af149a"
+uuid = "6fe1bfb0-de20-5000-8ca7-80f57d26f881"
+version = "0.11.3"
+
 [[OrderedCollections]]
 deps = ["Random", "Serialization", "Test"]
 git-tree-sha1 = "c4c13474d23c60d20a67b217f1d7f22a40edf8f1"
diff -r 8ff7da7bc77d -r 0d99f8f7d261 Project.toml
--- a/Project.toml	Sat Dec 14 14:59:59 2019 +0200
+++ b/Project.toml	Sat Dec 14 19:26:33 2019 +0200
@@ -8,5 +8,6 @@
 ColorTypes = "3da002f7-5984-5a60-b8a6-cbb66c0b333f"
 FileIO = "5789e2e9-d7fb-5bc7-8068-2c6fae9b9549"
 GR = "28b8d3ca-fb5f-59d9-8090-bfdbd6d07a71"
+OffsetArrays = "6fe1bfb0-de20-5000-8ca7-80f57d26f881"
 Printf = "de0858da-6303-5e67-8744-51eddeeeb8d7"
 Setfield = "efcf1570-3423-57d1-acb7-fd33fddbac46"
diff -r 8ff7da7bc77d -r 0d99f8f7d261 src/ImFilter.jl
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/ImFilter.jl	Sat Dec 14 19:26:33 2019 +0200
@@ -0,0 +1,58 @@
+##################################################
+# Simple (and fast for small filters compared to
+# ImageFiltering) image filtering
+##################################################
+
+__precompile__()
+
+module ImFilter
+
+using OffsetArrays
+
+##########
+# Exports
+##########
+
+export simple_imfilter
+
+##############
+# The routine
+##############
+
+@inline function inside(i, aʹ, bʹ, a, b)
+     return (max(a, i - aʹ) - i):(min(b,  i + bʹ) - i)
+end
+
+function simple_imfilter(b::Array{Float64,2},
+                         kernel::OffsetArray{Float64,2,Array{Float64,2}})
+
+    n, m = size(b)
+    k, 𝓁 = size(kernel)
+    o₁, o₂ = kernel.offsets
+    a₁, a₂ = k + o₁, 𝓁 + o₂
+    b₁, b₂ = -1 - o₁, -1 - o₂
+    kp = kernel.parent
+
+    @assert(isodd(k) && isodd(𝓁))
+
+    res = similar(b)
+
+    Threads.@threads for i=1:n
+        for j=1:m
+            tmp = 0.0
+            it₁ = inside(i, a₁, b₁, 1, n)
+            it₂ = inside(j, a₂, b₂, 1, m)
+            for p=it₁
+                @simd for q=it₂
+                    tmp += @inbounds(kp[p-o₁, q-o₂]*b[i+p,j+q])
+                end
+            end
+            res[i, j] = tmp
+        end
+    end
+
+    return res
+end
+
+end # Module
+
diff -r 8ff7da7bc77d -r 0d99f8f7d261 src/ImageTools.jl
--- a/src/ImageTools.jl	Sat Dec 14 14:59:59 2019 +0200
+++ b/src/ImageTools.jl	Sat Dec 14 19:26:33 2019 +0200
@@ -8,6 +8,7 @@
 include("Translate.jl")
 include("Denoise.jl")
 include("Visualise.jl")
+include("ImFilter.jl")
 
 end # module