[BUG] VapourSynth Levels filter does not work for RGB24 image streams

[shijan]

Seems there is also a problem that 16 bit RGB image imported to Hybrid incorrectly processed as 8 bit RGB24

# Imports
import vapoursynth as vs
core = vs.get_core()
# loading source: /Users/shph/Desktop/No name.tif
# color sampling RGB24@16, matrix:709, scantyp: progressive
# luminance scale PC
# resolution: 800x600
# frame rate: -1 fps
# Loading /Users/shph/Desktop/No name.tif using vsImageReader
clip = core.imwri.Read(["/Users/shph/Desktop/No name.tif"])
clip = core.std.Loop(clip=clip, times=100)
# Input color space is assumed to be RGB24.
# making sure frame rate is set to 25
clip = core.std.AssumeFPS(clip, fpsnum=25, fpsden=1)
# Setting color range to PC (full) range.
clip = core.std.SetFrameProp(clip=clip, prop="_ColorRange", intval=0)
# adjusting output color from: RGB24 to YUV422P10 for ProResModel (i422)
clip = core.resize.Bicubic(clip=clip, format=vs.YUV422P10, matrix_s="709", range_s="full")
# Output
clip.set_output()