Added notes and checks of the new limitation that if ICNR is used the…

…n the upsample factor must be an integer

niftynet/layer/subpixel.py

@@ -15,6 +15,11 @@ class SubPixelLayer(TrainableLayer):
  SubPixel Convolution initialised with ICNR initialisation
  and followed by an AveragePooling
 
+ Limitations:
+
+ If ICNR initialization is used then the upsample factor
+ MUST be an integer
+
  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  Shi, W., Caballero, J., Huszár, F., Totz, J., Aitken, A.P.,
  Bishop, R., Rueckert, D. and Wang, Z., 2016.
@@ -88,6 +93,8 @@ def __init__(
 
  if upsample_factor <= 0:
  raise ValueError("The upsampling factor must be strictly positive.")
+ if int(upsample_factor)!=float(upsample_factor) and use_icnr:
+ raise ValueError("If ICNR initialization is used the sample factor must be an integer")
 
  self.upsample_factor = upsample_factor
  self.kernel_size = kernel_size