Another update from ingydotnet^djgoku

Task/Image-convolution/J/image-convolution-1.j

@@ -0,0 +1,10 @@
+NB. pad the edges of an array with border pixels
+NB. (increasing the first two dimensions by 1 less than the kernel size)
+pad=: adverb define
+  'a b'=. (<. ,. >.) 0.5 0.5 p. $m
+  a"_`(0 , ] - 1:)`(# 1:)}~&# # b"_`(0 , ] - 1:)`(# 1:)}~&(1 { $) #"1 ]
+)
+
+kernel_filter=: adverb define
+   ($m)+/ .*&(,m)&(,/);._3 m pad
+)

Task/Image-convolution/J/image-convolution-2.j

@@ -0,0 +1,7 @@
+   NB. kernels borrowed from C and TCL implementations
+   sharpen_kernel=: _1+10*4=i.3 3
+   blur_kernel=: 3 3$%9
+   emboss_kernel=: _2 _1 0,_1 1 1,:0 1 2
+   sobel_emboss_kernel=: _1 _2 _1,0,:1 2 1
+
+   'blurred.ppm' writeppm~ blur_kernel kernel_filter readppm 'original.ppm'

Task/Image-convolution/J/image-convolution.j

@@ -1,11 +0,0 @@
-NB. pad the first n dimensions of an array with zeros
-NB. (increasing all dimensions by 1 less than the kernel size)
-pad=: adverb define
-  adj1=: <.m%2
-  adj2=: m-1
-  (-@(adj2 + ]) {. (adj1 + ]) {. [) (#m) {. $
-)
-
-kernel_filter=: adverb define
-  [: ,/"(-#$m) ($m) +/@(,/^:(_1+#$m))@:*&m;._3  ($m)pad
-)