add self-rag (#1070)

### What problem does this PR solve?

#1069 

### Type of change

- [x] New Feature (non-breaking change which adds functionality)

deepdoc/parser/pdf_parser.py

@@ -1021,6 +1021,8 @@ class RAGFlowPdfParser:
 
         self.page_cum_height = np.cumsum(self.page_cum_height)
         assert len(self.page_cum_height) == len(self.page_images) + 1
+        if len(self.boxes) == 0 and zoomin < 9: self.__images__(fnm, zoomin * 3, page_from,
+                                                                page_to, callback)
 
     def __call__(self, fnm, need_image=True, zoomin=3, return_html=False):
         self.__images__(fnm, zoomin)