function five(){

var imageData=ctx1.getImageData(0,0,canvas1.width,canvas1.height);

var pixdata=imageData.data;

var R=1;

var num=(2*R+1)*(2*R+1)

//先遍歷出每個像素

for(var i=R;i<canvas2.width-R;i++){

for(var j=R;j<canvas2.height-R;j++){

var totalr=0;

var totalg=0;

var totalb=0;

//在遍歷出每一個像素周圍的九個像素，讓后對著九個像素的r,g,b三個值分別求和在除9得到的值賦給這個像素。

for(var dx=-R;dx<=R;dx++){

for(var dy=-R;dy<=R;dy++){

var x=i+dx;

var y=j+dy;

var p=x*canvas2.width+y;

totalr+=pixdata[p*4+0];

totalg+=pixdata[p*4+1];

totalb+=pixdata[p*4+2];

}

var t=i*canvas2.width+j;

pixdata[t*4+0]=totalr/num;

pixdata[t*4+1]=totalg/num;

pixdata[t*4+2]=totalb/num;

}

}

}

ctx2.putImageData(imageData,0,0,0,0,canvas2.width,canvas2.height);

}