fix: add missing function

app.py

@@ -2,8 +2,9 @@ import gradio
 import numpy
 
 from pathlib import Path
+from PIL import Image
 
-from fastai.vision.all import load_learner, PILImage
+from fastai.vision.all import load_learner, PILImage, PILMask
 
 
 MODEL_PATH = Path('.') / 'models'
@@ -11,6 +12,33 @@ TEST_IMAGES_PATH = Path('.') / 'test'
 LEARNER = load_learner(MODEL_PATH / 'car-segmentation_v1.pkl')
 
 
+def preprocess_mask(file_name):
+    """Ensures masks are in grayscale format and removes transparency."""
+    mask_path = Path('/kaggle/input/car-segmentation/car-segmentation/masks') / file_name.name
+    mask = Image.open(mask_path)
+
+    # Convert palette-based images to RGBA first to ensure proper color interpretation
+    if mask.mode == 'P':
+        mask = mask.convert('RGBA')  
+    
+    # Convert any non-RGBA images to RGBA
+    if mask.mode != 'RGBA':
+        mask = mask.convert('RGBA')
+
+    mask_data = mask.getdata()
+
+    # Replace fully transparent pixels with black (or another valid label)
+    new_mask_data = [
+        (r, g, b, 255) if a > 0 else (0, 0, 0, 255)  # Ensure full opacity in new mask
+        for r, g, b, a in mask_data
+    ]
+    
+    mask.putdata(new_mask_data)
+
+    # Convert to grayscale after handling transparency
+    return PILMask.create(mask.convert('L'))
+
+
 def segment_image(image):
     image = PILImage.create(image)
     prediction, _, _ = LEARNER.predict(image)