Fix vignetting on P4

opendm/multispectral.py

@@ -110,8 +110,12 @@ def vignette_map(photo):
 
         # compute the vignette polynomial for each distance - we divide by the polynomial so that the
         # corrected image is image_corrected = image_original * vignetteCorrection
+        vignette = np.polyval(vignette_poly, r)
+
+        # DJI is special apparently
+        if photo.camera_make != "DJI":
+            vignette = 1.0 / vignette
 
-        vignette = 1.0 / np.polyval(vignette_poly, r)
         return vignette, x, y
     
     return None, None, None

opendm/photo.py

@@ -668,6 +668,7 @@ class ODM_Photo:
                 # Different camera vendors seem to use different ordering for the coefficients
                 if self.camera_make != "Sentera":
                     coeffs.reverse()
+
                 return coeffs
 
     def get_utc_time(self):