Currently, the CPU compositor smoothes its input size in variable size
mode. It is unclear why this is the case, but it seems the logic is that
sharp transitions in the size input are undesirable. Alternatively, this
is similar to the morphological blurring step in the Defocus node. But
it does not use standard weights and it is not morphological in nature
at all.
This patch removes the smoothing step and uses the original size
provided by the user. Looking at resources online, it seems users almost
always expect the size inputs to be used directly, so there is no reason
for force smooth their inputs.
Pull Request: https://projects.blender.org/blender/blender/pulls/118757
aa17aca9ec