polish nouri 0.6.0 startup and desktop header

nouri/images.py

@@ -4,10 +4,18 @@ import os
 import uuid
 from pathlib import Path
 
-from PIL import Image, ImageOps, UnidentifiedImageError
 from werkzeug.datastructures import FileStorage
 from werkzeug.utils import secure_filename
 
+try:
+    from PIL import Image, ImageOps, UnidentifiedImageError
+    PILLOW_AVAILABLE = True
+except ImportError:  # pragma: no cover - local fallback when Pillow is unavailable
+    Image = None
+    ImageOps = None
+    UnidentifiedImageError = OSError
+    PILLOW_AVAILABLE = False
+
 
 ALLOWED_IMAGE_EXTENSIONS = {"png", "jpg", "jpeg", "gif", "webp"}
 IMAGE_VARIANTS = {
@@ -54,6 +62,8 @@ def remove_photo_assets(upload_folder: str | Path, filename: str | None) -> None
 
 
 def _open_image(upload: FileStorage) -> Image.Image:
+    if not PILLOW_AVAILABLE or Image is None or ImageOps is None:
+        raise OSError("Pillow ist nicht verfügbar.")
     upload.stream.seek(0)
     image = Image.open(upload.stream)
     image.load()
@@ -61,6 +71,8 @@ def _open_image(upload: FileStorage) -> Image.Image:
 
 
 def _prepare_image(image: Image.Image) -> Image.Image:
+    if not PILLOW_AVAILABLE:
+        return image
     if image.mode not in {"RGB", "RGBA"}:
         image = image.convert("RGBA" if "A" in image.getbands() else "RGB")
     return image