blur2.rb

require 'pp'

class Image
	attr_accessor :array

	def initialize(array)
		@array = array
	end

	def output_image
		array.each { |a,b,c,d| puts "#{a} #{b} #{c} #{d}" }
	end

	def detect_ones
		arr = []
		array.each_with_index do |row, y|
			row.each_with_index do |e, x|
				arr << [x, y] if e == 1
			end
		end
		arr
	end

	def blur
		detect_ones.each do |x,y|
			write x,   y+1, 1
			write x,   y-1, 1
			write x+1, y,   1
			write x-1, y,   1
		end
	end

	def write(x, y, value)
		raise 'error' unless array.size >= y && array[y] && array[y].size >= x
		array[y][x] = value
	end
end

image = Image.new(
[ [0, 0, 0, 0],
[0, 1, 0, 0],
[0, 0, 0, 1],
[0, 0, 0, 0]
])
image.output_image
image.blur
image.output_image