function base64_encode_image ($filename=string,$filetype=string) {
    if ($filename) {
        $imgbinary = fread(fopen($filename, "r"), filesize($filename));
        return 'data:image/' . $filetype . ';base64,' . base64_encode($imgbinary);
    }
}

http://php.net/manual/en/function.base64-encode.php

used as so

<style>
.logo {
    background: url("<?php>") no-repeat right 5px;
}
</style>

or

<img src="<?php>"/>

Base64 Image Encode

image

PHP