refactored code; added watermark and nsfw facilities to app config route

invokeai/backend/image_util/invisible_watermark.py

@@ -0,0 +1,34 @@
+"""
+This module defines a singleton object, "invisible_watermark" that
+wraps the invisible watermark model. It respects the global "invisible_watermark"
+configuration variable, that allows the watermarking to be supressed.
+"""
+import numpy as np
+import cv2
+from PIL import Image
+from imwatermark import WatermarkEncoder
+from invokeai.app.services.config import InvokeAIAppConfig
+import invokeai.backend.util.logging as logger
+config = InvokeAIAppConfig.get_config()
+
+class InvisibleWatermark:
+    """
+    Wrapper around InvisibleWatermark module.
+    """
+    
+    @classmethod
+    def invisible_watermark_available(self) -> bool:
+        return config.invisible_watermark
+
+    @classmethod
+    def add_watermark(self, image: Image, watermark_text:str) -> Image:
+        if not self.invisible_watermark_available():
+            return image
+        logger.debug(f'Applying invisible watermark "{watermark_text}"')
+        bgr = cv2.cvtColor(np.array(image.convert("RGB")), cv2.COLOR_RGB2BGR)
+        encoder = WatermarkEncoder()
+        encoder.set_watermark('bytes', watermark_text.encode('utf-8'))
+        bgr_encoded = encoder.encode(bgr, 'dwtDct')
+        return Image.fromarray(
+            cv2.cvtColor(bgr_encoded, cv2.COLOR_BGR2RGB)
+        ).convert("RGBA")