Hello,
now i found time to test and unity and c# are new but thats right it works without the colordithering, thx.
test with primitive functionplotter:

Code:
...
float z = 0.0f;
for(float y = -3.0f; y < 3.0f; y=y+0.1f)
{
for(float x = -3.0f; x < 3.0f; x=x+0.1f)
{
z=Mathf.Sin(x)* Mathf.Cos(y);
coloredCubesVolume.data.SetVoxel((int)(x*10+20), (int)(z*10+20), (int)(y*10+20), new QuantizedColor((byte)(z*125+125),0,0,255));
}
}
...
merry xmas and a happy new year 2014 for the community and the Sirs Williams!