gistfile1.sh

#! /bin/bash

x=`identify -format "%w" $1`
y=`identify -format "%h" $1`
data=`openssl base64 < $1 | tr -d '\n'`
type=`file --mime-type -b $1`

echo "display:block;
  font:0/0 a;
  color:transparent;
  width:"$x"px;
  height:"$y"px;
  background:url('data:"$type";base64,"$data"');" | pbcopy

echo "Done."