make sure that the filter does not change the default data_type

nabu/preproc/alignment.py

@@ -361,7 +361,7 @@ class AlignmentBase(object):
                 img.shape[-2:], cutoff_lowpass=low_pass, cutoff_highpass=high_pass
             )
             # fft2 and iff2 use axes=(-2, -1) by default
-            img = my_ifft2(my_fft2(img) * my_fft_layout_adapt(img_filter)).real
+            img = my_ifft2(my_fft2(img) * my_fft_layout_adapt(img_filter.astype(self.data_type))).real
 
         if median_filt_shape is not None:
             img_shape = img.shape