Преобразование цвета RGB в HLS

{ Максимальные значения }
const
  HLSMAX = 240;
  RGBMAX = 255;
  UNDEFINED = (HLSMAX*2) div 3;
var
  H, L, S: integer; { H-оттенок, L-яркость, S-насыщенность }
  R, G, B: integer; { цвета }

procedure RGBtoHLS;
var
  cMax, cMin: integer;
  Rdelta, Gdelta, Bdelta: single;
begin
  cMax := max( max(R,G), B);
  cMin := min( min(R,G), B);
  L := round( ( ((cMax+cMin)*HLSMAX) + RGBMAX )/(2*RGBMAX) );

  if (cMax = cMin) then
  begin
    S := 0;
    H := UNDEFINED;
  end
  else
  begin
    if (L <= (HLSMAX/2)) then
      S := round( ( ((cMax-cMin)*HLSMAX) + ((cMax+cMin)/2) ) / (cMax+cMin) )
    else
      S := round( ( ((cMax-cMin)*HLSMAX) + ((2*RGBMAX-cMax-cMin)/2) ) 
      / (2*RGBMAX-cMax-cMin) );
    Rdelta := ( ((cMax-R)*(HLSMAX/6)) + ((cMax-cMin)/2) ) / (cMax-cMin);
    Gdelta := ( ((cMax-G)*(HLSMAX/6)) + ((cMax-cMin)/2) ) / (cMax-cMin);
    Bdelta := ( ((cMax-B)*(HLSMAX/6)) + ((cMax-cMin)/2) ) / (cMax-cMin);
    if (R = cMax) then
      H := round(Bdelta - Gdelta)
    else
    if (G = cMax) then
      H := round( (HLSMAX/3) + Rdelta - Bdelta)
    else
      H := round( ((2*HLSMAX)/3) + Gdelta - Rdelta );
    if (H < 0) then
      H:=H + HLSMAX;
    if (H > HLSMAX) then
      H:= H - HLSMAX;
  end;
  if S<0 then
    S:=0;
  if S>HLSMAX then
    S:=HLSMAX;
  if L<0 then
    L:=0;
  if L>HLSMAX then
    L:=HLSMAX;
end;


procedure HLStoRGB;
var
  Magic1, Magic2: single;

  function HueToRGB(n1, n2, hue: single): single;
  begin
    if (hue < 0) then
      hue := hue+HLSMAX;
    if (hue > HLSMAX) then
      hue:=hue - HLSMAX;
    if (hue < (HLSMAX/6)) then
      result:= ( n1 + (((n2-n1)*hue+(HLSMAX/12))/(HLSMAX/6)) )
    else
    if (hue < (HLSMAX/2)) then
      result:=n2
    else
    if (hue < ((HLSMAX*2)/3)) then
      result:= ( n1 + (((n2-n1)*(((HLSMAX*2)/3)-hue)+(HLSMAX/12))/(HLSMAX/6)))
    else
      result:= ( n1 );
  end;

begin
  if (S = 0) then
  begin
    B:=round( (L*RGBMAX)/HLSMAX );
    R:=B;
    G:=B;
  end
  else
  begin
    if (L <= (HLSMAX/2)) then
      Magic2 := (L*(HLSMAX + S) + (HLSMAX/2))/HLSMAX
    else
      Magic2 := L + S - ((L*S) + (HLSMAX/2))/HLSMAX;
    Magic1 := 2*L-Magic2;
    R := round( (HueToRGB(Magic1,Magic2,H+(HLSMAX/3))*RGBMAX + (HLSMAX/2))/HLSMAX );
    G := round( (HueToRGB(Magic1,Magic2,H)*RGBMAX + (HLSMAX/2)) / HLSMAX );
    B := round( (HueToRGB(Magic1,Magic2,H-(HLSMAX/3))*RGBMAX + (HLSMAX/2))/HLSMAX );
  end;
  if R<0 then
    R:=0;
  if R>RGBMAX then
    R:=RGBMAX;
  if G<0 then
    G:=0;
  if G>RGBMAX then
    G:=RGBMAX;
  if B<0 then
    B:=0;
  if B>RGBMAX then
    B:=RGBMAX;
end;