$ file datafile
datafile: PNG image data, 640 x 480, 8-bit colormap, non-interlaced
$ openssl base64 -e -in datafile >datafile.b64
$ file datafile.b64
datafile.b64: ASCII text
$ openssl base64 -d -in datafile.b64 >datafile2
$ md5sum datafile datafile2
c8f00e2b29d5b516d2c2afd8e41dcdfd  datafile
c8f00e2b29d5b516d2c2afd8e41dcdfd  datafile2