function setImage(direction){
	var img = document.getElementById('current_diapo');
	if(direction=='back' ){
		current_image-=1;
	}else if(direction=='next'){
		current_image+=1;
	}
	var view = document.getElementById('view');
	view.innerHTML =current_image;
	var previous = document.getElementById('btn_previous_image');
	if(current_image==1){
		previous.style.display="none";
	}else{
		previous.style.display="block";
	}
	var next = document.getElementById('btn_next_image');
	if(current_image ==max_image){
		next.style.display="none";
	}else{
		next.style.display="block";
	}
	img.src=img_url[current_image];
	img.width=img_width[current_image];
	img.height=img_height[current_image];
}