Show preprocessing preview only when substantive options are selected

Only show preprocessing options and preview when meaningful options like grayscale,
threshold, denoise, or contrast adjustments are selected, rather than just rotation.

app.py

@@ -511,8 +511,13 @@ with main_tab1:
                                           help="Select a document to process with OCR")
             st.markdown('</div>', unsafe_allow_html=True)
         
-        # Show preprocessing summary if options are selected
-        if uploaded_file is not None and any(preprocessing_options.values()):
+        # Show preprocessing summary only if substantive options are selected
+        substantive_options = (preprocessing_options.get("grayscale", False) or 
+                              preprocessing_options.get("threshold", False) or 
+                              preprocessing_options.get("denoise", False) or 
+                              preprocessing_options.get("contrast", 0) != 0)
+                              
+        if uploaded_file is not None and substantive_options:
             st.write("**Active preprocessing:**")
             prep_list = []
             
@@ -577,8 +582,8 @@ with main_tab1:
                         except Exception:
                             st.info("Image preview could not be displayed")
                     
-                    # Add processed preview if preprocessing options are selected
-                    if any(preprocessing_options.values()):
+                    # Add processed preview ONLY if substantive preprocessing options are selected
+                    if preprocessing_options.get("grayscale", False) or preprocessing_options.get("threshold", False) or preprocessing_options.get("denoise", False) or preprocessing_options.get("contrast", 0) != 0:
                         # Create a before-after comparison
                         st.subheader("Preprocessing Preview")