fix: process pdf once

app.py

@@ -166,9 +166,9 @@ with gr.Blocks() as demo:
 
     def select_image(evt: gr.SelectData, gallery):
         selected = gallery[evt.index]
-        return selected, selected
+        return selected
 
-    image_gallery.select(select_image, image_gallery, [selected_image, preview_image])
+    image_gallery.select(select_image, image_gallery, selected_image)
     convert_button.click(convert_pdf_to_images, inputs=[pdf_input], outputs=[gr.Textbox(visible=False), image_gallery])
     ocr_button.click(ocr_process, inputs=[selected_image, got_mode, ocr_color, ocr_box], outputs=ocr_output)