Javascript image embedding

How do you make a png into something like this?

var googleicon	 = "data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAoAAAAKCAIAAAACUFjqAAAAiklEQVQY02MUjfmmFxPFgAuIxnz7jwNcU9BngSjae%2FbDxJUPj1z%2BxMDAYKPLlx8u72wswMDAwASRnrjyIQMDw%2BoW3XfbbfPD5SFchOGCHof2nHmPaTgTpmuEPA8LeR6GsKHSNrp8E1c%2B3Hv2A8QKG10%2BiDjUaRD7Qmsuw51GlMcYnXcE4AqSyRn3Abz4culPbiCuAAAAAElFTkSuQmCC";

Anyone know?