反过来我会.
procedure TForm1.Button1Click(Sender: TObject);
var
JpegImage: TJPEGImage;
BmpImage: TImage;
begin
BmpImage := TImage.Create(self);
Jpegimage := TJPEGImage.Create;
BmpImage.Picture.LoadFromFile('Tower.bmp'); //装入位图文件
JpegImage.Assign(BmpImage.Picture.Bitmap);
JpegImage.SaveToFile('Tower.jpg'); //保存为JPEG文件
BmpImage.Free;
JpegImage.Free ;
end;