init で設定変更する必要があった。
init に「convert_urls: false,」を追加すれば http から絶対パスで画像 URL を指定してもそのまま入るようになる。
<script>
tinyMCE.init({
// General options
mode : "exact",
theme : "advanced",
elements : "tiny_edit1, tiny_edit2, tiny_edit3",
plugins : "safari,pagebreak,style,layer,table,save,advhr,advimage,advlink,emotions,iespell,inlinepopups,insertdatetime,preview,media,searchreplace,print,contextmenu,paste,directionality,fullscreen,noneditable,visualchars,nonbreaking,xhtmlxtras,template",
//日本語にします
language : "ja",
// Theme options
theme_advanced_buttons1 : "save,newdocument,|,bold,italic,underline,strikethrough,|,justifyleft,justifycenter,justifyright,justifyfull,styleselect,formatselect,fontselect,fontsizeselect",
theme_advanced_buttons2 : "cut,copy,paste,pastetext,pasteword,|,search,replace,|,bullist,numlist,|,outdent,indent,blockquote,|,undo,redo,|,link,unlink,anchor,image,cleanup,help,code,|,insertdate,inserttime,preview,|,forecolor,backcolor",
theme_advanced_buttons3 : "tablecontrols,|,hr,removeformat,visualaid,|,sub,sup,|,charmap,iespell,media,advhr,|,print,|,ltr,rtl,|,fullscreen",
theme_advanced_toolbar_location : "top",
theme_advanced_toolbar_align : "left",
theme_advanced_statusbar_location : "bottom",
theme_advanced_resizing : true,
relative_urls : false,
convert_urls: false,
// Example content CSS (should be your site CSS)
content_css : "css/content.css",
// Drop lists for link/image/media/template dialogs
template_external_list_url : "lists/template_list.js",
external_link_list_url : "lists/link_list.js",
external_image_list_url : "lists/image_list.js",
media_external_list_url : "lists/media_list.js"
});
</script>