Color conversion - Convert2CMYK and Convert2Gray

Q: Are there any samples on how to use the Convert2CMYK and
Convert2GrayScale functions in C#? I am having a difficult time trying
to figure it out.
A: Usage of 'Convert2CMYK' and 'Convert2GrayScale' methods is similar
to 'Convert2RGB'.

The following code example is extracted from ElementReaderAdvTest
sample project:

if (element.IsFilled())
  GState gs = element.GState();
  ColorSpace cs_fill = gs.GetFillColorSpace();
  ColorPt fill = gs.GetFillColor();
  ColorPt outc = new ColorPt();
  cs_fill.Convert2RGB(fill, outc);

  int r = (int)(rgb.get_c(0)*255);
  int g = (int)(rgb.get_c(1)*255);
  int b = (int)(rgb.get_c(2)*255);

To obtain grayscale value, you could use the following code:

  ColorSpace cs = ....
  cs_fill.Convert2Gray(in, out);

  // out.get_c(0) is in the range [0..1]
  int gray = (int)(out.get_c(0)*255);

similarly for CMYK:

  ColorSpace cs = ....
  cs_fill.Convert2CMYK(in, out);
  int c = (int)(out.get_c(0)*255);
  int m = (int)(out.get_c(1)*255);
  int y = (int)(out.get_c(2)*255);
  int k = (int)(out.get_c(3)*255);