Waifu2x-w2xc

[Selur]

Not totally sure whether I make a mistake in using Waifu2x or if this is a bug.
When I use limited range input and feed it to Waifu2x the histogram is compressed.
To illustrate the problem I created the following script:

# Imports
import vapoursynth as vs
core = vs.get_core()
import ctypes
# Loading Support Files
Dllref = ctypes.windll.LoadLibrary("I:/Hybrid/64bit/vsfilters/ResizeFilter/Waifu2x/w2xc.dll")
# Loading Plugins
core.std.LoadPlugin(path="I:/Hybrid/64bit/vsfilters/ResizeFilter/Waifu2x/Waifu2x-w2xc.dll")
core.std.LoadPlugin(path="I:/Hybrid/64bit/vsfilters/Support/fmtconv.dll")
core.std.LoadPlugin(path="I:/Hybrid/64bit/vsfilters/SourceFilter/LSmashSource/vslsmashsource.dll")
# Loading C:\Users\Selur\Desktop\test3.mkv using LWLibavSource
clip = core.lsmas.LWLibavSource(source="C:/Users/Selur/Desktop/test3.mkv", format="YUV420P10", cache=0, prefer_hw=0)

#limited
limited = clip
limited = core.resize.Point(limited, matrix_in_s="470bg",range_s="limited")
limited = core.std.AssumeFPS(limited, fpsnum=24000, fpsden=1001) # making sure frame rate is set to 23.976
limited = core.std.SetFrameProp(clip=limited, prop="_ColorRange", intval=1) # Setting color range to TV (limited) range.
limited = core.resize.Bicubic(clip=limited, format=vs.RGB48, matrix_in_s="470bg", range_s="limited") # adjusting color space from YUV420P10 to RGB48 for Waifu2x-w2xc
limited = core.resize.Bicubic(clip=limited, format=vs.YUV420P16, matrix_s="470bg", range_s="limited") # to YUV420P16
limited = core.hist.Classic(clip=limited) # add histogram

# limited with waifu2x
limitedw = clip
limitedw = core.resize.Point(limitedw, matrix_in_s="470bg",range_s="limited")
limitedw = core.std.AssumeFPS(limitedw, fpsnum=24000, fpsden=1001) # making sure frame rate is set to 23.976
limitedw = core.std.SetFrameProp(clip=limitedw, prop="_ColorRange", intval=1) # Setting color range to TV (limited) range.
limitedw = core.resize.Bicubic(clip=limitedw, format=vs.RGB48, matrix_in_s="470bg", range_s="limited") # adjusting color space from YUV420P10 to RGB48 for Waifu2x-w2xc
limitedw = core.fmtc.bitdepth(clip=limitedw,bits=32) # adjusting bit depth to 32bit
limitedw = core.w2xc.Waifu2x(clip=limitedw, scale=1) # using Waifu2x
limitedw = core.resize.Bicubic(clip=limitedw, format=vs.YUV420P16, matrix_s="470bg", range_s="limited") # to YUV420P16
limitedw = core.hist.Classic(clip=limitedw) # add histogram

# full
full = clip
full = core.resize.Point(full, matrix_in_s="470bg",range_s="full")
full = core.std.AssumeFPS(full, fpsnum=24000, fpsden=1001) # making sure frame rate is set to 23.976
full = core.std.SetFrameProp(clip=full, prop="_ColorRange", intval=0) # Setting color range to PC (full) range.
full = core.resize.Bicubic(clip=full, format=vs.YUV420P16, matrix_s="470bg", range_s="full") # 16bit
full = core.hist.Classic(clip=full) # add histogram


# full with waifu2x
fullw = clip
fullw = core.resize.Point(fullw, matrix_in_s="470bg",range_s="full")
fullw = core.std.AssumeFPS(fullw, fpsnum=24000, fpsden=1001) # making sure frame rate is set to 23.976
fullw = core.std.SetFrameProp(clip=fullw, prop="_ColorRange", intval=0) # Setting color range to PC (full) range.
fullw = core.resize.Bicubic(clip=fullw, format=vs.RGB48, matrix_in_s="470bg", range_s="full") # adjusting color space from YUV420P10 to RGB48 for Waifu2x-w2xc
fullw = core.fmtc.bitdepth(clip=fullw,bits=32) # adjusting bit depth to 32bit
fullw = core.w2xc.Waifu2x(clip=fullw, scale=1) # using Waifu2x
fullw = core.resize.Bicubic(clip=fullw, format=vs.YUV420P16, matrix_s="470bg", range_s="full") # 16bit
fullw = core.hist.Classic(clip=fullw) # add histogram

limitedstack = core.std.StackHorizontal([limited,limitedw])
fullstack = core.std.StackHorizontal([full,fullw])
clip = core.std.StackVertical([limitedstack,fullstack])

# Output
clip.set_output()

which compares what happens to the histogram if the source is interpreted as 'full' or 'limited', converted to RGB48 and then fed to Waifu2x.

I uploaded the script I used and the source to my GoogleDrive as test.mkv and Waifu2x_Test.vpy

So my question is:
Is this a bug or am I doing something wrong?

In case I'm doing something wrong it would be nice if someone could post how to properly handle limited sources with Waifu2x.
Thanks!

Cu Selur