Add the center shift argument to nnedi3_rpow2, and no chroma shift correction will be needed:
Code:
nnedi3_rpow2(2, cshift="Spline16Resize")
EDIT Note,
- I tested your script sans dither calls, for simplicity
- I tested at 4x enlargement to exaggerate the artifacts. The output looks great; this is a good idea!
- nnedi3_rpow2 does not accept Y8, only YV12, YUY2 and RGB24 - at least for me.
Code:
## source = YV12
y=nnedi3_rpow2(4, cshift="Spline16Resize")
u=UToY8.ConvertToYV12
\ .nnedi3_rpow2(8, cshift="Spline16Resize")
v=VToY8.ConvertToYV12
\ .nnedi3_rpow2(8, cshift="Spline16Resize")
YToUV(u, v, y)
## output=YV24
EDIT 2 completely wrong, please ignore