require 'libpng'


p = Png.read(ARGV.shift)
colmap = ARGV.shift || '012345678'

if p.height == 32 or p.width == 32	# want 16x16
	tog = true
	p.lines.delete_if { tog = !tog }
	p.lines.each { |l| l.replace l.unpack('C*').find_all { tog = !tog }.pack('C*') }
end

puts p.lines.map { |l| l.unpack('C*').join.gsub(/(\d)/) { colmap[$1.to_i].chr rescue ' ' } }