Grayscale Images – colored on hover for e.g. Partnerlogo Element

there was a thread here but closed – so i set up a new one.

you can see it here: http://www.wordpress-webdesign.org/grayscale/

because of having some troubles with the common css Solution (filter setting grayscale) i use the code Element to implement a little jquery script.

<script type="text/javascript"> 
	
	// jQuery(".graytone img").css({"display":"none");
	
	// On window load. This waits until images have loaded which is essential
	jQuery(window).load(function(){
		
		// Fade in images so there isn't a color "pop" document load and then on window load
		jQuery(".graytone img").animate({opacity:1},500);
		
		// clone image
		jQuery('.graytone img').each(function(){
			var el = jQuery(this);
			el.css({"position":"absolute"}).wrap("<div class='img_wrapper' style='display: inline-block'>").clone().addClass('img_grayscale').css({"position":"absolute","z-index":"998","opacity":"0"}).insertBefore(el).queue(function(){
				var el = jQuery(this);
				el.parent().css({"width":this.width,"height":this.height});
				el.dequeue();
			});
			this.src = grayscale(this.src);
		});
		
		// Fade image 
		jQuery('.graytone img').mouseover(function(){
			jQuery(this).parent().find('img:first').stop().animate({opacity:1}, 1000);
		})
		jQuery('.img_grayscale').mouseout(function(){
			jQuery(this).stop().animate({opacity:0}, 1000);
		});		
	});
	
	// Grayscale w canvas method
	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();
    }
	    
</script>

you can place it e.g before a partnerlogo element:

with :

here i gave to the partner logo element a custom css class : graytone
you can find that class in the script above on line ( // jQuery(".graytone img").css({"display":"none"); )
(how to activate the custom css for every alb element put in funktions.php : add_theme_support('avia_template_builder_custom_css');)

there are some adjustements you can make (fade in speed, animation speed)