Initial data commit

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

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+NB. pad the edges of an array with border pixels
+NB. (increasing the first two dimensions by 1 less than the kernel size)
+pad=: {{
+   rank=.#$m
+   'first second'=. (<.,:>.)-:$m
+    -@(second+rank{.$) {. (first+rank{.$){.]
+}}
+
+kernel_filter=: {{
+   [: (0 >. 255 <. <.@:+&0.5) (1,:$m)+/ .*~&(,/)&m;._3 m pad
+}}

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

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+NB. kernels borrowed from C and TCL implementations
+id_kernel=: (=&i.-)3 3
+sharpen_kernel=: ({ _1,#@,)id_kernel
+blur_kernel=: ($ *&%/)3 3
+emboss_kernel=: id_kernel+(+/~ - >./)i.3
+sobel_emboss_kernel=: (i:-:<:3)*/1+(<.|.)i.3
+
+   'blurred.ppm' writeppm~ blur_kernel kernel_filter readppm 'original.ppm'