This works for images that are not tiled.
function init() {
var map = L.map('map', {
maxZoom: 24,
minZoom: 1,
crs: L.CRS.Simple
}).setView([0, 0], 1);
map.setMaxBounds(new L.LatLngBounds([0,500], [500,0]));
var imageUrl = 'http://www.lib.utexas.edu/maps/historical/newark_nj_1922.jpg'
var imageBounds = [[250,0], [0,250]];
L.imageOverlay(imageUrl, imageBounds).addTo(map);
}