Update app.py

app.py

@@ -2,43 +2,45 @@ import gradio as gr
 from PIL import Image
 import numpy as np
 
-def brightness_to_white_alpha(img, invert_opacity=False):
+def brightness_to_white_alpha(img, bg_img=None, invert_opacity=False):
     if img is None:
         return None
 
-    # Step 1: Convert to RGB
+    # Step 1: Convert input to RGB and compute brightness
     img_rgb = img.convert("RGB")
     img_np = np.array(img_rgb).astype(np.float32)
+    brightness = np.dot(img_np[..., :3], [0.299, 0.587, 0.114])
 
-    # Step 2: Calculate brightness (luminance)
-    brightness = np.dot(img_np[..., :3], [0.299, 0.587, 0.114])  # shape: (H, W)
-
-    # Step 3: Invert if requested
     if invert_opacity:
         brightness = 255 - brightness
 
-    # Step 4: Normalize to 0–255 alpha
     alpha = brightness.clip(0, 255).astype(np.uint8)
 
-    # Step 5: Create solid white RGB image
+    # Step 2: Create solid white RGBA image
     height, width = alpha.shape
-    white_rgb = np.full((height, width, 3), 255, dtype=np.uint8)  # White RGB
+    white_rgb = np.full((height, width, 3), 255, dtype=np.uint8)
+    white_rgba = np.dstack((white_rgb, alpha))  # shape (H, W, 4)
+    white_img = Image.fromarray(white_rgba, mode="RGBA")
+
+    # Step 3: Overlay white image on background (if provided)
+    if bg_img:
+        bg = bg_img.convert("RGBA").resize(white_img.size)
+        composite = Image.alpha_composite(bg, white_img)
+        return composite
 
-    # Step 6: Combine into final RGBA image
-    white_rgba = np.dstack((white_rgb, alpha))  # shape: (H, W, 4)
-    out_img = Image.fromarray(white_rgba, mode="RGBA")
-    return out_img
+    return white_img
 
 # Gradio UI
 iface = gr.Interface(
     fn=brightness_to_white_alpha,
     inputs=[
         gr.Image(type="pil", label="Input Image"),
+        gr.Image(type="pil", label="Optional Background Image"),
         gr.Checkbox(label="Invert Brightness → Alpha", value=False)
     ],
-    outputs=gr.Image(type="pil", label="White Image with Brightness-Based Alpha"),
-    title="🕊️ Brightness to Alpha (White Glow Generator)",
-    description="Generates a pure white image where transparency is based on brightness — dark = transparent, light = opaque."
+    outputs=gr.Image(type="pil", label="Final Output"),
+    title="💡 White Brightness Layer + Optional Background",
+    description="Generates a pure white image with brightness as transparency. Optionally overlays it on a background."
 )
 
 if __name__ == "__main__":