Color inaccurate under low bitdepth like 8 bit (obvious under mutliple passes)

[dtlnor]

platform: Win10, VS-C
version: V3

By comparing the following output, for multiple passes boxblur.

src8.std.BoxBlur(planes=[0,1,2],hradius=1,vradius=1,hpasses=3,vpasses=3).set_output(1)

pass1 = muf.BoxFilter(src8, radius=2)
pass2 = muf.BoxFilter(pass1, radius=2)
pass3 = muf.BoxFilter(pass2, radius=2)
pass3.set_output(2)

src8.box.Blur(planes=[0,1,2],hradius=1,vradius=1,hpasses=3,vpasses=3).set_output(3)

pass1 = src8.box.Blur(planes=[0,1,2],hradius=1,vradius=1,hpasses=1,vpasses=1)
pass2 = pass1.box.Blur(planes=[0,1,2],hradius=1,vradius=1,hpasses=1,vpasses=1)
pass3 = pass2.box.Blur(planes=[0,1,2],hradius=1,vradius=1,hpasses=1,vpasses=1)
pass3.set_output(4)

https://slow.pics/c/NV0vNwAA

the color looks a bit red in general for output 3 and 4 using box.Blur

[WolframRhodium]

Thanks!