insert and preview an image with 'insert-file but coding system fault

[gombiuda JHL]

I can easily insert an image file and preview it in emacs. But when I save it with C-x C-s or C-x C-w emacs will inform me that there is something wrong with the coding system. Here is the detail:
---------------------------------------------------------------------------
These default coding systems were tried to encode text
in the buffer `xxx.org':
  (utf-8-unix (7209 . 4194185) (7238 . 4194185) (7259 . 4194273) (7261
  . 4194208) (7262 . 4194300) (7266 . 4194228) (7272 . 4194204) (7273
  . 4194284) (7274 . 4194205) (7276 . 4194204) (7278 . 4194247))
However, each of them encountered characters it couldn't encode:
  utf-8-unix cannot encode these:           ...

Click on a character (or switch to this window by `C-x o'
and select the characters by RET) to jump to the place it appears,
where `C-u C-x =' will give information about it.

Select one of the safe coding systems listed below,
or cancel the writing with C-g and edit the buffer
   to remove or modify the problematic characters,
or specify any other coding system (and risk losing
   the problematic characters).

  raw-text emacs-mule no-conversion
---------------------------------------------------------------------------
And after I press enter emacs will save the file but if I try to open it another time, the characters will become like this "\xxx\xxx\xxx".
So what can I do to solve this problem?
Is it possible to insert an image and the coding system would not occur this problem?

Thanks
gombiuda