Fix color balance logic for Sentinel-2 TIFFs by using global instead of per-channel percentile stretching

inference/geotiff.py

@@ -88,55 +88,19 @@ def normalize_rgb(
 ):
     """
     Convert Sentinel-2 reflectance/DN values to uint8 RGB.
-
-    Percentile normalization is performed independently
-    for each channel.
+    Global percentile normalization preserves color balance.
     """
-
     rgb = rgb.astype(np.float32)
+    
+    # Calculate global percentiles across all channels to preserve color balance
+    low = np.percentile(rgb, lower_percentile)
+    high = np.percentile(rgb, upper_percentile)
 
-    result = np.zeros_like(
-        rgb,
-        dtype=np.uint8
-    )
-
-    for channel in range(3):
-
-        band = rgb[:, :, channel]
-
-        low = np.percentile(
-            band,
-            lower_percentile
-        )
-
-        high = np.percentile(
-            band,
-            upper_percentile
-        )
-
-        if high <= low:
-            result[:, :, channel] = np.clip(
-                band,
-                0,
-                255
-            ).astype(np.uint8)
-
-        else:
-
-            normalized = (
-                (band - low) /
-                (high - low)
-            )
-
-            normalized = np.clip(
-                normalized,
-                0,
-                1
-            )
-
-            result[:, :, channel] = (
-                normalized * 255
-            ).astype(np.uint8)
+    if high <= low:
+        result = np.clip(rgb, 0, 255).astype(np.uint8)
+    else:
+        normalized = (rgb - low) / (high - low)
+        result = (np.clip(normalized, 0, 1) * 255).astype(np.uint8)
 
     return result