try
 Image1.Picture.Graphic := nil;
 Image1.Picture.LoadFromFile(jpegfile);
except
 on EInvalidGraphic do
 Image1.Picture.Graphic := nil;
end;
if Image1.Picture.Graphic is TJPEGImage then
begin
 TJPEGImage(Image1.Picture.Graphic).Scale := Self.Scale;
 TJPEGImage(Image1.Picture.Graphic).Performance := jpBestSpeed;
end;