Clear image attributes (good when going responsive)

// CLEAR IMAGES ATTRIBUTES
function image_tag_class($class, $id, $align, $size) {
    $align = 'align' . esc_attr($align);
    return $align;
}
add_filter('get_image_tag_class', 'image_tag_class', 0, 4);
function image_tag($html, $id, $alt, $title) {
    return preg_replace(array(
            '/\s+width="\d+"/i',
            '/\s+height="\d+"/i',
            '/alt=""/i'
        ),
        array(
            '',
            '',
            '',
            'alt="' . $title . '"'
        ),
        $html);
}
add_filter('get_image_tag', 'image_tag', 0, 4);