feat: exposure detection (over/underexposed)

analyzer.py

@@ -1,5 +1,6 @@
 import cv2
 import numpy as np
+from PIL import Image
 
 
 def is_blurry(path: str, threshold: float = 100.0) -> bool:
@@ -9,3 +10,20 @@ def is_blurry(path: str, threshold: float = 100.0) -> bool:
         return False
     variance = cv2.Laplacian(img, cv2.CV_64F).var()
     return bool(variance < threshold)
+
+
+def _mean_brightness(path: str) -> float:
+    """Durchschnittliche Helligkeit eines Bildes (0-255)."""
+    img = Image.open(path).convert("L")
+    arr = np.array(img, dtype=np.float32)
+    return float(arr.mean())
+
+
+def is_overexposed(path: str, threshold: float = 240.0) -> bool:
+    """Gibt True zurueck, wenn das Bild ueberbelichtet ist."""
+    return _mean_brightness(path) > threshold
+
+
+def is_underexposed(path: str, threshold: float = 30.0) -> bool:
+    """Gibt True zurueck, wenn das Bild unterbelichtet ist."""
+    return _mean_brightness(path) < threshold

tests/test_analyzer.py

@@ -25,3 +25,22 @@ def test_normal_image_is_not_blurry(tmp_path):
     p = tmp_path / "sharp.jpg"
     img.save(p)
     assert is_blurry(str(p), threshold=100) is False
+
+
+from analyzer import is_overexposed, is_underexposed
+
+
+def test_white_image_is_overexposed(tmp_path):
+    path = make_test_image(tmp_path, color=(255, 255, 255))
+    assert is_overexposed(path, threshold=240) is True
+
+
+def test_dark_image_is_underexposed(tmp_path):
+    path = make_test_image(tmp_path, color=(10, 10, 10))
+    assert is_underexposed(path, threshold=30) is True
+
+
+def test_normal_image_is_neither(tmp_path):
+    path = make_test_image(tmp_path, color=(128, 128, 128))
+    assert is_overexposed(path, threshold=240) is False
+    assert is_underexposed(path, threshold=30) is False