Give RGB, Blue priority

opendm/multispectral.py

@@ -181,8 +181,11 @@ def get_primary_band_name(multi_camera, user_band_name):
     if len(multi_camera) < 1:
         raise Exception("Invalid multi_camera list")
     
-    # multi_camera is already sorted by band_index
+    # Pick RGB, or Blue if available, otherwise first band
     if user_band_name == "auto":
+        for band in multi_camera:
+            if band['name'].lower() in ['rgb', 'redgreenblue', 'blue', 'b']:
+                return band['name']
         return multi_camera[0]['name']
 
     for band in multi_camera: