refactor: strip EXIF orientation before Gemini analysis for coordinate accuracy

Instead of transforming coordinates after Gemini returns crop_bounds, strip EXIF
orientation from image before sending to Gemini. This ensures:
- Gemini analyzes the same raw image as our backend
- crop_bounds are in raw image coordinate space
- No coordinate transformation needed
- Works for all images (with or without EXIF)

Added strip_exif_orientation() utility that removes orientation tag and
re-encodes image. Used in extract_label endpoint before sending to Gemini.

backend/routers/items.py

@@ -10,7 +10,7 @@ from slowapi.util import get_remote_address
 from pathlib import Path
 from .. import models, schemas, auth
 from ..database import get_db
-from ..services.image_processing import ImageProcessor
+from ..services.image_processing import ImageProcessor, strip_exif_orientation
 from ..services.image_storage import save_image, get_unique_filename
 from ..logger import log
 
@@ -104,8 +104,12 @@ async def extract_label(
             detail="File exceeds 10MB limit."
         )
 
-    log.info(f"[EXTRACT] Sending {len(contents)} bytes to Gemini for analysis")
-    result = extract_label_info(contents, mode=mode)
+    # Strip EXIF orientation so Gemini analyzes raw image (not rotated)
+    # Backend will process the same raw image
+    contents_no_exif = strip_exif_orientation(contents)
+    log.info(f"[EXTRACT] Sending {len(contents_no_exif)} bytes to Gemini (EXIF orientation stripped)")
+
+    result = extract_label_info(contents_no_exif, mode=mode)
     log.info(f"[EXTRACT] Gemini returned: {type(result).__name__}")
     return result
 

backend/services/image_processing.py

@@ -22,6 +22,46 @@ import numpy as np
 logger = logging.getLogger(__name__)
 
 
+def strip_exif_orientation(file_bytes: bytes) -> bytes:
+    """
+    Remove EXIF orientation metadata from image bytes.
+
+    Returns image bytes with orientation tag removed (or set to 1 = normal).
+    This ensures both Gemini and our backend analyze the same raw image.
+
+    Args:
+        file_bytes: Raw image file bytes
+
+    Returns:
+        Image bytes with EXIF orientation stripped
+    """
+    try:
+        image = Image.open(io.BytesIO(file_bytes))
+
+        # Try to get and remove EXIF orientation
+        try:
+            exif_dict = piexif.load(image.info.get('exif', b''))
+            if piexif.ImageIFD.Orientation in exif_dict['0th']:
+                del exif_dict['0th'][piexif.ImageIFD.Orientation]
+                exif_bytes = piexif.dump(exif_dict)
+            else:
+                exif_bytes = None
+        except:
+            exif_bytes = None
+
+        # Save image without orientation
+        output = io.BytesIO()
+        if exif_bytes:
+            image.save(output, format='JPEG', quality=85, exif=exif_bytes)
+        else:
+            image.save(output, format='JPEG', quality=85)
+
+        return output.getvalue()
+    except Exception as e:
+        logger.warning(f"Failed to strip EXIF orientation: {e}, returning original bytes")
+        return file_bytes
+
+
 class ImageProcessor:
     """Service for processing uploaded images with smart features."""
 
@@ -85,19 +125,12 @@ class ImageProcessor:
             self.logger.info(msg)
             print(f">>> {msg}")  # Explicit print for visibility
 
-            # Extract EXIF orientation (but don't apply yet)
+            # Extract EXIF orientation (but don't apply it)
             exif_orientation = self._extract_exif_orientation(image)
+            if exif_orientation and exif_orientation > 1:
+                self.logger.info(f"[PROCESS] Note: Image has EXIF orientation {exif_orientation}, will be applied after crop")
 
-            # Transform crop_bounds from EXIF-applied space to raw space
-            if crop_bounds and exif_orientation and exif_orientation > 1:
-                crop_bounds = self._transform_crop_bounds_by_exif(
-                    crop_bounds, exif_orientation, original_size[0], original_size[1]
-                )
-                msg = f"[CROP] EXIF {exif_orientation} transform applied: {crop_bounds}"
-                self.logger.info(msg)
-                print(f">>> {msg}")
-
-            # Smart cropping (on raw, un-rotated image so crop_bounds match AI analysis)
+            # Smart cropping (on raw image - crop_bounds come from Gemini analyzing same raw image)
             cropped_image = image
             crop_size = None
             text_angle = None
@@ -213,44 +246,6 @@ class ImageProcessor:
             self.logger.debug(f"Could not extract EXIF orientation: {e}")
             return None
 
-    def _transform_crop_bounds_by_exif(
-        self, crop_bounds: Dict, orientation: int, raw_width: int, raw_height: int
-    ) -> Dict:
-        """
-        Transform crop_bounds from EXIF-applied space to raw image space.
-
-        Gemini analyzes images with EXIF applied, returning crop_bounds in that space.
-        We need to transform them back to raw image coordinates before cropping.
-
-        Args:
-            crop_bounds: {x, y, width, height} in EXIF-applied space
-            orientation: EXIF orientation value (1-8)
-            raw_width: raw image width (before EXIF)
-            raw_height: raw image height (before EXIF)
-
-        Returns:
-            Transformed crop_bounds in raw image space
-        """
-        if orientation == 1:
-            # No rotation, use as-is
-            return crop_bounds
-        elif orientation == 6:
-            # Rotate 90 CW: raw (w×h) appears as displayed (h×w)
-            # Transform from displayed (h×w) back to raw (w×h)
-            x, y, w, h = crop_bounds['x'], crop_bounds['y'], crop_bounds['width'], crop_bounds['height']
-            # After 90° CW: (x,y) in raw → (raw_height - y, x) in displayed
-            # Reverse: (x,y) in displayed → (y, raw_width - x) in raw
-            return {
-                'x': y,
-                'y': raw_width - x - w,
-                'width': h,
-                'height': w
-            }
-        else:
-            # Other orientations: return as-is (TODO: implement if needed)
-            self.logger.warning(f"EXIF orientation {orientation} not supported for crop_bounds transform, using as-is")
-            return crop_bounds
-
     def _rotate_by_orientation(
         self, image: Image.Image, orientation: int
     ) -> Image.Image: