html+qjquery 實現變色

$(document).ready(function() {
       
     
   $(window).load(function(){
                
                $("#item img").fadeIn(500);
                
                $('#item img').each(function(){
                 var el = $(this); 
                        el.css({"position":"absolute"}).wrap("<div class='img_wrapper' style='display: inline-block' mce_style='display: inline-block'>")
      .clone().addClass('img_grayscale').css({"position":"absolute","z-index":"998","opacity":"0"}).insertBefore(el).queue(function(){ 
                                var el = $(this); 
                                el.parent().css({"width":this.width,"height":this.height}); 
                                el.dequeue(); 
                        }); 
                        this.src = grayscale(this.src);
      
    });
                
               $('#item img').mouseover(function(){  $(this).parent().find('img:first').stop().animate({opacity:1}, 1000);}); $('.img_grayscale').mouseout(function(){$(this).stop().animate({opacity:0}, 1000);  });
         });
 
         $('#item img').click(function(){
    $("#item img").attr('src',"../images/46.png");
   });
         function grayscale(src){
                var canvas = document.createElement('canvas'); 
                var ctx = canvas.getContext('2d'); 
                var imgObj = new Image(); 
                imgObj.src = src; 
                canvas.width = imgObj.width; 
                canvas.height = imgObj.height; 
                ctx.drawImage(imgObj, 0, 0); 
                var imgPixels = ctx.getImageData(0, 0, canvas.width, canvas.height); 
                for(var y = 0; y < imgPixels.height; y++){ 
                        for(var x = 0; x < imgPixels.width; x++){ 
                                var i = (y * 4) * imgPixels.width + x * 4; 
                                var avg = (imgPixels.data[i] + imgPixels.data[i + 1] + imgPixels.data[i + 2]) / 3; 
                                imgPixels.data[i] = avg; 
                                imgPixels.data[i + 1] = avg; 
                                imgPixels.data[i + 2] = avg; 
                        } 
                } 
                ctx.putImageData(imgPixels, 0, 0, 0, 0, imgPixels.width, imgPixels.height); 
                return canvas.toDataURL(); 
     }
});