diff --git a/src/image/sub_image.py b/src/image/sub_image.py
index f10f35c..3c3aec7 100644
--- a/src/image/sub_image.py
+++ b/src/image/sub_image.py
@@ -68,7 +68,7 @@ class SubImageCombine:
 
 		for ix in range(nx):
 			for iy in range(ny):
-				patch = _np.asarray(np.reshape(subimages[ix * ny + iy], (self.n_ch, self.sx, self.sy)))
+				patch = np.asnumpy(np.reshape(subimages[ix * ny + iy], (self.n_ch, self.sx, self.sy)))
 				x0, y0 = ix * self.px, iy * self.py
 				accum[:, x0:x0+self.sx, y0:y0+self.sy] += patch
 				count[0, x0:x0+self.sx, y0:y0+self.sy] += 1.0