--- rxvt-unicode/src/rxvtimg.C	2012/06/03 18:49:55	1.6
+++ rxvt-unicode/src/rxvtimg.C	2012/06/04 06:59:50	1.10
@@ -215,6 +215,22 @@
   //TODO
 }
 
+rxvt_img *
+rxvt_img::convert_to (XRenderPictFormat *new_format)
+{
+  rxvt_img *img = new rxvt_img (s, new_format, w, h);
+
+  Display *dpy = s->display->dpy;
+  Picture src = XRenderCreatePicture (dpy, pm, format, 0, 0);
+  Picture dst = XRenderCreatePicture (dpy, img->pm, new_format, 0, 0);
+
+  XRenderComposite (dpy, PictOpSrc, src, None, dst, 0, 0, 0, 0, 0, 0, w, h);
+
+  XRenderFreePicture (dpy, src);
+  XRenderFreePicture (dpy, dst);
+
+  return img;
+}
 
 #endif