Update app.py

app.py

@@ -2,57 +2,53 @@ import gradio as gr
 from PIL import Image
 import numpy as np
 
-def brightness_to_opacity_overlay(mask_img, bg_img, invert_opacity=False):
+def white_alpha_overlay(mask_img, bg_img, invert_opacity=False):
     if mask_img is None or bg_img is None:
         return None
 
-    # Convert images and resize mask to match background
+    # Convert and resize
     mask = mask_img.convert("RGB")
     bg = bg_img.convert("RGBA")
     mask = mask.resize(bg.size)
 
-    # Convert mask to brightness-based alpha
+    # Convert brightness to alpha
     mask_np = np.array(mask).astype(np.float32)
     brightness = np.dot(mask_np[..., :3], [0.299, 0.587, 0.114])
-    alpha = (255 - brightness if invert_opacity else brightness).clip(0, 255)
-    alpha = alpha / 255.0  # normalize to 0-1
+    if invert_opacity:
+        brightness = 255 - brightness
+    alpha = brightness.clip(0, 255) / 255.0  # 0-1
 
-    # Normalize mask RGB
-    rgb = mask_np / 255.0
+    # Create solid white RGBA with computed alpha
+    white = np.ones_like(mask_np) / 255.0  # RGB = 1.0 (white)
+    white_rgba = np.dstack((white, alpha))  # shape (H, W, 4)
 
-    # Combine original RGB with generated alpha
-    overlay_rgba = np.dstack((rgb, alpha))  # shape: (H, W, 4)
-
-    # Convert background to float32
+    # Background as float
     bg_np = np.array(bg).astype(np.float32) / 255.0
 
-    # Extract alphas
-    alpha_fg = overlay_rgba[..., 3:4]
+    # Blend overlay on top of background
+    alpha_fg = white_rgba[..., 3:4]
     alpha_bg = bg_np[..., 3:4]
-
-    # Premultiplied blend
     out_alpha = alpha_fg + alpha_bg * (1 - alpha_fg)
-    out_rgb = (overlay_rgba[..., :3] * alpha_fg + bg_np[..., :3] * alpha_bg * (1 - alpha_fg)) / np.maximum(out_alpha, 1e-6)
+    out_rgb = (white_rgba[..., :3] * alpha_fg + bg_np[..., :3] * alpha_bg * (1 - alpha_fg)) / np.maximum(out_alpha, 1e-6)
 
-    # Compose final image
+    # Final image
     out_img = np.dstack((out_rgb, out_alpha)).clip(0, 1) * 255
-    final = Image.fromarray(out_img.astype(np.uint8), mode="RGBA")
-
-    return final
+    result = Image.fromarray(out_img.astype(np.uint8), mode="RGBA")
+    return result
 
 # Gradio UI
 iface = gr.Interface(
-    fn=brightness_to_opacity_overlay,
+    fn=white_alpha_overlay,
     inputs=[
-        gr.Image(type="pil", label="Mask Image (Color OK)"),
-        gr.Image(type="pil", label="Background Image (Supports Alpha)"),
-        gr.Checkbox(label="Invert Brightness", value=False)
+        gr.Image(type="pil", label="Mask Image (Used for Brightness → Alpha)"),
+        gr.Image(type="pil", label="Background Image (With Alpha OK)"),
+        gr.Checkbox(label="Invert Brightness to Alpha", value=False)
     ],
-    outputs=gr.Image(type="pil", label="Composite Result"),
-    title="✨ Brightness-to-Alpha with Color Mask",
+    outputs=gr.Image(type="pil", label="White Overlay Composite"),
+    title="🕊️ Brightness-to-Alpha White Overlay",
     description=(
-        "Uses the brightness of a colored image as opacity, preserves color, "
-        "and overlays it onto a background image (even with alpha transparency)."
+        "Converts the brightness of the top image into opacity, sets the image color to white, "
+        "and overlays it on a background. Works with full transparency."
     )
 )