How do I set RGB colorants in the range 0..255?

Q: What are the supported RGB value for the watermark color? Currently
we are using just red, blue and green and we would like to add more
color options. I tried the values 120,120,120 for gray it didn't work
A: You can use any possible RGB value (or CMYK, Gray, etc).
The only problem is that colorant values in PDF are represented in the
range [0,1].

So to convert the RGB values in the range [0.255] to [0,1] use the
following line.

ColorPt mycolor = new ColorPt(120/255.0, 120/255.0, 120/255.0);

i.e. divide each colorant value with 255.0.