ConsoleImage.rb

class ConsoleImage

	def initialize(m, n)
		@m = m
		@n = n
		@colors = Array.new(m * n)
		clear
	end

	def clear
		@colors.fill "0"
	end
	
	def light(x, y, color)
		@colors[(x - 1) * @n + y - 1] = color
	end

	def to_s
		lines = ""
		@colors.each_slice(@m) {|row| lines << row.reduce("") {|acc, it| acc << it } + "\n"}
		lines
	end

end

main.rb

# encoding: utf-8

$:.unshift File.dirname(__FILE__)

require "console_image"

i = ConsoleImage.new(5, 3)
i.light(5, 3, "1")
i.light(1, 5, "1")
i.light(1, 1, "1")
i.light(3, 5, "1")
puts i
i.clear
puts "-----"
puts i