Hello,
An example with red from the colordialog:
When converted with ColorToHSL :
procedure TForm1.Button1Click(Sender: TObject);
Var
  H, S, L : double;
begin
  if colordialog1.execute then
  begin
    ColorToHSL(colordialog1.Color, H, S, L);
    ImageEnView1.Proc.Colorize(round(H), round(S), L);
    Caption := 'H :  ' + floattostr(H) + '    S :  ' + floattostr(S)  + '    L :  ' + floattostr(L);
  end;
end;
When converted with ColorToHSL, I get the values H=0, S=1, L=0.5.
ImageEnView1.Proc.Colorize(0, 1, 0.5);
I get a gray image :)