delphi图片二值化函数

function TImageFunc.binaryzation2(souBMP:TBitmap):TBitmap;
var
  p:PByteArray;
  Gray,x,y:Integer;
  Bmp:TBitmap;
begin
  try
    Bmp:=TBitmap.Create;
    Bmp.Assign(souBMP);
    Bmp.PixelFormat:=pf24Bit;
    randomize;
    for y:=0 to Bmp.Height-1 do
     begin
      Bmp.Canvas.Lock;
      p:=Bmp.ScanLine[y];
      for x:=0 to Bmp.Width-1 do
      begin
        Gray:=Round(p[x*3+2]*0.3+p[x*3+1]*0.59+p[x*3]*0.11);
        if gray > 128 then
        begin
          p[x*3]:=255;
          p[x*3+1]:=255;
          p[x*3+2]:=255;
        end
      else
        begin
          p[x*3]:=0;
          p[x*3+1]:=0;
          p[x*3+2]:=0;
        end;