RGBToHSB

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;

type
  TForm1 = class(TForm)
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}
uses
  Math;

type
  TRGBColor = record
    Red,
    Green,
    Blue: Byte;
  end;

  THSBColor = record
    Hue,
    Saturnation,
    Brightness: Double;
  end;

function RGBToHSB(rgb: TRGBColor): THSBColor;
var
  minRGB, maxRGB, delta: Double;
  h, s, b: Double;
begin
   H := 0.0;
   minRGB := Min(Min(rgb.Red, rgb.Green), rgb.Blue);
   maxRGB := Max(Max(rgb.Red, rgb.Green), rgb.Blue);
   delta:= ( maxRGB - minRGB );
   b:= maxRGB;
   if (maxRGB <> 0.0) then s := 255.0 * Delta / maxRGB
   else s := 0.0;
   if (s <> 0.0) then
   begin
     if rgb.Red = maxRGB then h := (rgb.Green - rgb.Blue) / Delta
     else
       if rgb.Green = maxRGB then h := 2.0 + (rgb.Blue - rgb.Red) / Delta
       else
         if rgb.Blue = maxRGB then h := 4.0 + (rgb.Red - rgb.Green) / Delta
   end
   else h := -1.0;
   h := h * 60;
   if h < 0.0 then h := h + 360.0;
   with result do
   begin
     Hue := h;
     Saturnation := s * 100 / 255;
     Brightness := b * 100 / 255;
   end;
end;

//测试:
procedure TForm1.Button1Click(Sender: TObject);
var
  rgb: TRGBColor;
  hsb: THSBColor;
begin
  rgb.Red := 255;
  rgb.Green := 0;
  rgb.Blue := 0;

  hsb := RGBToHSB(rgb);

  ShowMessage(FloatToStr(hsb.Hue));         //0
  ShowMessage(FloatToStr(hsb.Saturnation)); //100
  ShowMessage(FloatToStr(hsb.Brightness));  //100
end;

end.