function grayscaleImageIE(imgObj)
   {
       imgObj.style.filter = 'progid:DXImageTransform.Microsoft.BasicImage(grayScale=1)';
   }
function colorImageIE(imgObj)
   {
       imgObj.style.filter = 'progid:DXImageTransform.Microsoft.BasicImage(grayScale=0)';
   }
function grayscaleImage(imgObj)
   {
	  
      var canvas = document.createElement('canvas');
        var canvasContext = canvas.getContext('2d');
        
        var imgW = imgObj.width;
        var imgH = imgObj.height;
        canvas.width = imgW;
        canvas.height = imgH;
        canvasContext.drawImage(imgObj, 0, 0);
        var imgPixels = canvasContext.getImageData(0, 0, imgW, imgH);
        
        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;
            }
        }
        
        canvasContext.putImageData(imgPixels, 0, 0, 0, 0, imgPixels.width, imgPixels.height);
        return canvas.toDataURL();
    }





function saturate(x)
{
	if (x=="a")
	{
		var image = document.getElementById("photo_nouveaute");
		
	}
	if (x=="b")
	{
		var image = document.getElementById("image_promos");
		
	}
	if(document.all)
	{	
		colorImageIE(image);
	}
	else
	{
		if (x=="a")
		{
			image.src = image1_initial_src;
		
		}
		if (x=="b")
		{
			image.src = image2_initial_src;
		
		}
	}
}

function desaturate(x)
{
	if (x=="a")
	{
		var image = document.getElementById("photo_nouveaute");
	}
	if (x=="b")
	{
		var image = document.getElementById("image_promos");
	}
	if(document.all)
	{
		grayscaleImageIE(image);
	}

	else
	{
		image.src = grayscaleImage(image);
	}
}

function init2()
{
	var image = document.getElementById("photo_nouveaute");
	var image2 = document.getElementById("image_promos");
	image1_initial_src = image.src;
	image2_initial_src = image2.src;
}

function init_desaturate()
{
	
	var image = document.getElementById("photo_nouveaute");
	var image2 = document.getElementById("image_promos");
		
	if(document.all)
	{
		grayscaleImageIE(image);
		grayscaleImageIE(image2);
	}

	else
	{
		
		image1_initial_src = image.src;
		image2_initial_src = image2.src;
		
		image.src = grayscaleImage(image);
		
		image2.src = grayscaleImage(image2);
		
		
	}
	
}