From: Colin Wilson <colin@wilsonc.demon.co.uk>
Subject: Re: HSL to RGB?
Date: 11 May 2000 00:00:00 GMT
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Newsgroups: borland.public.delphi.graphics

const
  RGBMAX = 255;
  HLSMAX=240;
  UNDEFINED = HLSMAX * 2 div 3;


function HueToRGB(n1,n2,hue : Integer) : word;
begin
  while hue > hlsmax do
    Dec (hue, HLSMAX);

  while hue < 0 do
    Inc (hue, HLSMAX);

  if hue < HLSMAX div 6 then
    result := ( n1 + (((n2-n1)*hue+(HLSMAX div 12)) div (HLSMAX div 6))
)
  else
    if hue < HLSMAX div 2 then
      result := n2
    else
      if hue < (HLSMAX*2) div 3 then
        result := n1 + (((n2-n1)*(((HLSMAX*2) div 3)-hue)+(HLSMAX div
12)) div (HLSMAX div 6))
      else
        result := n1
end;

procedure iHLSToRGB (hue, lum, sat : Integer; var r, g, b : Integer);
var
  Magic1,Magic2 : Integer;

begin
  if sat = 0 then
  begin
    r := (lum * RGBMAX) div HLSMAX;
    g := r;
    b := r;
  end
  else
  begin
    if lum <= HLSMAX div 2 then
      Magic2 := (lum*(HLSMAX + sat) + (HLSMAX div 2)) div HLSMAX
    else
      Magic2 := lum + sat - ((lum*sat) + (HLSMAX div 2)) div HLSMAX;

    Magic1 := 2*lum-Magic2;

    r := (HueToRGB (Magic1,Magic2,hue+(HLSMAX div 3))*RGBMAX + (HLSMAX
div 2)) div HLSMAX;
    g := (HueToRGB (Magic1,Magic2,hue)*RGBMAX + (HLSMAX div 2)) div
HLSMAX;
    b := (HueToRGB (Magic1,Magic2,hue-(HLSMAX div 3))*RGBMAX + (HLSMAX
div 2)) div HLSMAX;
  end;
end;



Colin
e-mail :colin@wilsonc.demon.co.uk
web: http://www.wilsonc.demon.co.uk/delphi.htm