error.txt

test.rb:14:in `[]': wrong number of arguments(2 for 1) (ArgumentError)
  from image.rb:14:in `block (2 levels) in black_and_white_array'
	from image.rb:13:in `times'
	from image.rb:13:in `block in black_and_white_array'
	from image.rb:11:in `times'
	from image.rb:11:in `black_and_white_array'
	from image.rb:27:in `<main>'

test.rb

require 'chunky_png'

def is_dark?(color)
  ChunkyPNG::Color.r(color) +
  ChunkyPNG::Color.g(color) +
  ChunkyPNG::Color.b(color) < 40
end

def black_and_white_array(image)
  array = Array.new
  image.width.times do |x|
    array[x] = Array.new
    image.height.times do |y|
      if is_dark? image[x,y]
        image = ChunkyPNG::Color.rgba(0, 0, 0, 128)
      else
        image = ChunkyPNG::Color.rgba(255, 255, 255, 128)
      end
    end
  end
  image.save("#{Time.now.to_i.to_s}.png", :fast_rgba)
  return array
end

# Image 1, the face of Charlie Sheen
image1 = ChunkyPNG::Image.from_file('image1.png')
array1 = black_and_white_array(image1)