How to colorize an image

Problem/Question/Abstract:

How to colorize an image

Answer:

Assumes 8 bit R, G, Bs packed into RGB. Luma is 0 - 255


function Colorize(RGB, Luma: Cardinal);
var
  l, r, g, b: Single;
begin
  Result := Luma;
  if Luma = 0 then { it's all black anyway}
    Exit;
  l := Luma / 255;
  r := RGB and $FF * l;
  g := RGB shr 8 and $FF * l;
  b := RGB shr 16 and $FF * l;
  Result := Round(b) shl 16 or Round(g) shl 8 or Round(r);
end;