for(var context=document.getElementById("board").getContext("2d"),imageData=context.getImageData(0,0,1500,1500),data=imageData.data,i=0;i<data.length;i+=4)data[i]=255-data[i],data[i+1]=255-data[i+1],data[i+2]=255-data[i+2];context.putImageData(imageData,0,0);