Как получить средний цвет между двумя цветами?

function GetColorBetween(StartColor, EndColor: TColor; Pointvalue, Von, Bis:
  Extended): TColor;
var
  F: Extended;
  r1, r2, r3, g1, g2, g3, b1, b2, b3: Byte;
  function CalcColorBytes(fb1, fb2: Byte): Byte;
  begin
    result := fb1;
    if fb1 < fb2 then
      Result := FB1 + Trunc(F * (fb2 - fb1));
    if fb1 > fb2 then
      Result := FB1 - Trunc(F * (fb1 - fb2));
  end;
begin
  if Pointvalue <= Von then
  begin
    result := StartColor;
    exit;
  end;
  if Pointvalue >= Bis then
  begin
    result := EndColor;
    exit;
  end;
  F := (Pointvalue - von) / (Bis - Von);
  asm
     mov EAX, Startcolor
     cmp EAX, EndColor
     je @@exit
     mov r1, AL
     shr EAX,8
     mov g1, AL
     shr Eax,8
     mov b1, AL
     mov Eax, Endcolor
     mov r2, AL
     shr EAX,8
     mov g2, AL
     shr EAX,8
     mov b2, AL
     push ebp
     mov al, r1
     mov dl, r2
     call CalcColorBytes
     pop ecx
     push ebp
     Mov r3, al
     mov dL, g2
     mov al, g1
     call CalcColorBytes
     pop ecx
     push ebp
     mov g3, Al
     mov dL, B2
     mov Al, B1
     call CalcColorBytes
     pop ecx
     mov b3, al
     XOR EAX,EAX
     mov AL, B3
     SHL EAX,8
     mov AL, G3
     SHL EAX,8
     mov AL, R3
     @@Exit:
     mov @result, eax
  end;
end;

//------------------------------------------------------------------------------
// Function for getting mixed color from two given colors, with a relative
// distance from two colors determined by Position value inside
// MinPosition..MaxPosition range
// Author: Dmitri Papichev (c) 2001
// License type: Freeware
//------------------------------------------------------------------------------
 
function GetMixedColor(const StartColor,
  EndColor: TColor;
  const MinPosition,
  Position,
  MaxPosition: integer): TColor;
var
  Fraction: double;
  R, G, B,
    R0, G0, B0,
    R1, G1, B1: byte;
begin
  {process Position out of range situation}
  if (MaxPosition < MinPosition) then
  begin
    raise Exception.Create
      ('GetMixedColor: MaxPosition is less then MinPosition');
  end; {if}
 
  {if Position is outside MinPosition..MaxPosition range, the closest boundary
   is effectively substituted through the adjustment of Fraction}
  Fraction :=
    Min(1, Max(0, (Position - MinPosition) / (MaxPosition - MinPosition)));
 
  {extract the intensity values}
  R0 := GetRValue(StartColor);
  G0 := GetGValue(StartColor);
  B0 := GetBValue(StartColor);
  R1 := GetRValue(EndColor);
  G1 := GetGValue(EndColor);
  B1 := GetBValue(EndColor);
 
  {calculate the resulting intensity values}
  R := R0 + Round((R1 - R0) * Fraction);
  G := G0 + Round((G1 - G0) * Fraction);
  B := B0 + Round((B1 - B0) * Fraction);
 
  {combine intensities in a resulting color}
  Result := RGB(R, G, B);
end; {--GetMixedColor--}

Взято с Delphi Knowledge Base: https://www.baltsoft.com/