Convert Images to be Relative

strip-http-https

function image_to_relative($html, $id, $caption, $title, $align, $url, $size, $alt) {
    $sp = strpos($html,"src=") + 5;
    $ep = strpos($html,"\"",$sp);

    $imageurl = substr($html,$sp,$ep-$sp);

    $relativeurl = str_replace("http://","",$imageurl);
    $sp = strpos($relativeurl,"/");
    $relativeurl = substr($relativeurl,$sp);

    $html = str_replace($imageurl,$relativeurl,$html);

    return $html;
}
add_filter('image_send_to_editor','image_to_relative',5,8);