Преобразование цвета RGB <> 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;

Зайцев О.В.

Владимиров А.М.

Взято из https://forum.sources.ru