`extractpng` not sure the source of this ```ruby #!/usr/bin/env ruby # extracts embedded PNG files from binary files def extract_png(input, output) hdr = input.read(8) hex = hdr.unpack("C8") if hex != [0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a] puts "Not a PNG File: #{hex}" return end output.write(hdr) loop do chunk_type = extract_chunk(input, output) break if chunk_type.nil? || chunk_type == "IEND" end end def extract_chunk(input, output) lenword = input.read(4) length = lenword.unpack("N")[0] type = input.read(4) data = length >= 0 ? input.read(length) : "" crc = input.read(4) if length < 0 || !(type[0,1] === ("A".."z")) return nil end output.write lenword output.write type output.write data output.write crc return type end unless ARGV[0] puts "Usage:" puts " pngextract [output filename]" exit 1 end infile = File.new ARGV[0], "rb" outname = ARGV[1] || ARGV[0] num = 0 loop do origpos = infile.pos regex = Regexp.new("\211PNG", nil, "n").match(infile.read) unless regex puts "done" exit end puts "Found PNG ##{num}" newpos = regex.begin(0) infile.seek origpos + newpos outfile = File.new(outname + ".#{num}.png", "wb") extract_png(infile, outfile) puts "PNG written to #{File.basename(outfile)}" num += 1 end ```