function changeimg( sens ) { //sens -> 1 ou -1
	img_encours += sens;
	objDiv1.style.display = "block";
	objDiv2.style.display = "block";
	if (img_encours == 0) {
	objDiv1.style.display = "none";
	}
	if (img_encours == myImages.length-1) {
	objDiv2.style.display = "none";
	}
	//document.getElementById("idcours").value = img_encours;
	document.photo.src=myImages[img_encours].src;
	document.getElementById("image_lien").href = myImagesUrl[img_encours];
	//document.form_suppr.fichiers_nom.value=myImages[img_encours].value;
	document.photo.width=myImages[img_encours].width;
	document.photo.height=myImages[img_encours].height;
}