这段让图片旋转90度的代码执行起来太慢了，请帮帮忙,该怎么处理

这段让图片旋转90度的代码执行起来太慢了，请帮帮忙
请问有无办法优化下，实在太慢了

var
i,j:integer;
begin

image2.Picture.Bitmap.Height:=image1.picture.width;
image2.Picture.Bitmap.Width:=image1.picture.height;
for i:=0 to image1.picture.Height do
for j:=0 to image1.picture.Width do
image2.canvas.Pixels[(-i+image1.picture.Height),j]:=image1.canvas.Pixels[j,i];


[解决办法]
用ScanLine的代码，速度很快：

Delphi(Pascal) code

procedure ImageRF(const Bitmap:TBitmap);vari,j:Integer;rowIn,rowOut:pRGBTriple;Bmp:TBitmap;Width,Height:Integer;beginBmp:=TBitmap.Create;Bmp.Width := Bitmap.Height;Bmp.Height := Bitmap.Width;Width:=Bitmap.Width-1;Height:=Bitmap.Height-1;if Bitmap.PixelFormat<>pf32Bit then Bitmap.PixelFormat:=pf24Bit;Bmp.PixelFormat:=Bitmap.PixelFormat;for j := 0 to Height dobeginrowIn := Bitmap.ScanLine[j];for i := 0 to Width dobeginrowOut := Bmp.ScanLine[i];Inc(rowOut,Height - j);rowOut^ := rowIn^;Inc(rowIn);end;end;Bitmap.Assign(Bmp);end;procedure TForm1.Button1Click(Sender: TObject);begin  ImageRF(Image1.Picture.Bitmap);end;