function remove_image() {
    for (i=2;i<7;i++) {
        if (document.getElementById("image"+i) != null) {
            document.getElementById("image"+i).style.visibility = 'hidden';
        }
    }
    document.getElementById("image").style.visibility = 'visible';
}

function change_image(image_id) {
    if (document.getElementById("image"+image_id) != null) {
        document.getElementById("image"+image_id).style.visibility = 'visible';
        document.getElementById("image").style.visibility = 'hidden';
    }
}

/* Clear searchbox-input field */
function clear_text() {
    var search_input = document.getElementById("keyword");
    if (search_input.value == 'Zoek op trefwoord') {
        search_input.value = "";
    }
}