Update app.py

app.py

@@ -1,5 +1,4 @@
 import streamlit as st
-import numpy as np
 import os
 import shutil
 import zipfile
@@ -59,10 +58,11 @@ if uploaded_file:
 
     # Show transformation steps
     st.subheader("🧬 Steps Preview")
-    cols = st.columns(min(3, len(options)))
+    num_cols = max(1, min(3, len(options)))  # fix for columns error
+    cols = st.columns(num_cols)
     for i, file in enumerate(sorted(os.listdir(output_dir))):
         img = Image.open(os.path.join(output_dir, file))
-        with cols[i % 3]:
+        with cols[i % num_cols]:
             st.image(img, caption=file[:-4], width=180)
 
     # Create ZIP