pgm picture generator (gray gradient pattern)

pgen.rb

#!/usr/bin/env ruby
HEIGHT = 1024
WIDTH = 1024

f = File.new("sample.pgm", "w")
f.puts "P2"
f.puts "#{HEIGHT} #{WIDTH}"
f.puts 255
f.puts "# Generated by pgen.rb (C) Akos Kovacs"
HEIGHT.times do |row|
   f.puts "# row #{row}"
   i = 0
   b = 0
   WIDTH.times do
       if (i == 255)
           i = 0
       end
       b += 1
       if (b == 20)
           f.print "\n"
           b = 0
       end
       f.print "#{i += 1} "
   end
end