Leer comentarios en un archivo Jpeg
 

Código Delphi [-]
function LeerCom(Stream: TStream): string;
var
  Buffer: array[0..$FFFF] of Char;
  Header: array[1..4] of byte;
  Size: Integer;
begin
  Stream.Seek(0,soFromBeginning);
  Stream.ReadBuffer(Header,2);
  if (Header[1] <> $FF) or (Header[2] <> $D8) then
    raise Exception.Create('Identificador incorrecto');
  repeat
    Stream.ReadBuffer(Header,4);
    Size:= ((Header[3] shl 8) + Header[4]) - 2;
    case Header[2] of
      $FE: begin
             FillChar(Buffer,Sizeof(Buffer),0);
             Stream.ReadBuffer(Buffer,Size);
             Result:= String(PChar(@Buffer));
           end;
      $01,$D0..$D9: Stream.Seek(-2,soFromCurrent) ;
      else Stream.Seek(Size,soFromCurrent);
    end;
  until (Result <> '') or (Header[2] = $DA);
end;

Ejemplo de uso (Se utiliza un TOpenDialog):

Código Delphi [-]
var
  Stream: TFileStream;
begin
  if OpenDialog1.Execute then
  begin
    Stream:= TFileStream.Create(OpenDialog1.FileName, fmOpenRead);
    try
      ShowMessage(LeerCom(Stream));
    finally
      Stream.Free;
    end;
  end;
end;