Fix fresnel sampling

Wrong factor 1/2 in code, due to assumed padding in reference paper.

src/hotopy/holo/propagation.py

@@ -98,7 +98,7 @@ def expand_fresnel_numbers(fresnel_nums, *, ndim=None, shape=None):
 
 def get_fresnel_critical_sampling(fresnel_nums) -> int:
     r"""
-    Return critical sampling condition for given image dimensions and pixel Fresnel number(s).
+    Return critical sampling condition for given pixel Fresnel number(s).
 
     This functions returns the minimal sampling points required in any dimensions. It is,
 
@@ -286,7 +286,7 @@ class FresnelTFPropagator(FourierConvolutionPropagator):
     def _init_kernel(self):
         # verify sufficient padding
         if not check_fresnelTF_sampling(self._pad_shape, self._fresnel_numbers):
-            n_min = get_fresnel_critical_sampling(self._pad_shape, self._fresnel_numbers)
+            n_min = get_fresnel_critical_sampling(self._fresnel_numbers)
             logger.warning(
                 UserWarning(
                     f"{self.__class__.__name__}: "