>perl -MMIME::Base64 -e 'print decode_base64("R0lGODlhAQABAIAAAP///wAAACH5BAEAAAAALAAAAAABAAEAAAICRAEAOw==")' > pixel.gif
>perl -MMIME::Base64 -e 'print unpack("H*",decode_base64("R0lGODlhAQABAIAAAP///wAAACH5BAEAAAAALAAAAAABAAEAAAICRAEAOw=="))'
47494638396101000100800000ffffff00000021f90401000000002c00000000010001000002024401003b
>perl -e 'print pack("H*","47494638396101000100800000ffffff00000021f90401000000002c00000000010001000002024401003b")' > pixel2.gif
>md5sum pixel.gif pixel2.gif
325472601571f31e1bf00674c368d335  pixel.gif
325472601571f31e1bf00674c368d335  pixel2.gif
>