canvas 改变图片色彩 _JavaScript

canvas 改变图片颜色
<!DOCTYPE html>

<!--    to moving elements in a straight line   -->

    <html>

        <head>

            <meta charset='utf-8'/>

            <script type="text/javascript"> 

                

                

                window.addEventListener('load',canvasApp, false);

                

                function canvasApp(args) {

                    var canvas = document.getElementById("MyCanvas");

                    var context = canvas.getContext("2d");

                    

                    var logoL = new Image();

                        logoL.src= "../img/csrLeft.png";

                    var widthL = 88;

                    var logoR = new Image();

                        logoR.src = "../img/csrRight.png";

                    var widthR = 286;

                    var height = 31;

                    context.drawImage(logoL,0,0);

                    

                    var dataL = context.getImageData(0,0,widthL,height);

                    

                    for (var i=0; i<dataL.data.length; i+=4 ) {

                        

                        dataL.data[i] = 29;

                        dataL.data[i+1] = 58;