请问怎么把JPG格式转成BMP？怎么把BMP转成JPG呢？

Question

//BMP转换为JPG 
procedure TStuXXSLForm.LoadImageBitBtnClick(Sender: TObject); 
var 
  MyJpeg:TJpegImage; 
begin 
  inherited; 
  if OpenPictureDialog1.Execute then 
  begin 
    FileName:=OpenPictureDialog1.FileName; 
    Image1.Picture.LoadFromFile(FileName); 
    if ExtractFileExt(FileName)='.Bmp' then 
    begin 
      MyJpeg:= TJpegImage.Create; 
      MyJpeg.Assign(Image1.Picture.Bitmap); 
      FileName:='Photo.Jpg'; 
      MyJpeg.SaveToFile(FileName); 
      MyJpeg.Free; 
    end; 
  end; 
end;

Answer 1

procedure JpgToBmp(const source,dest:string);
var
  MyJpeg: TJpegImage;
  bmp: Tbitmap;
begin
bmp:=tbitmap.Create;
MyJpeg:= TJpegImage.Create;
try
  myjpeg.LoadFromFile(source);
  bmp.Assign(myjpeg);
  bmp.SaveToFile(dest);
finally
  bmp.free;
  myjpeg.Free;
end;
end;procedure BmpToJpg(const source,dest:string;const scale:byte);
var
  MyJpeg: TJpegImage;
  Image1: TImage;
begin
Image1:= TImage.Create(application);
MyJpeg:= TJpegImage.Create;
try
  Image1.Picture.Bitmap.LoadFromFile(source);
  MyJpeg.Assign(Image1.Picture.Bitmap); 
  MyJpeg.CompressionQuality:=scale;
  MyJpeg.Compress;
  MyJpeg.SaveToFile(dest);
finally
  image1.free;
  myjpeg.Free;
end;
end;