$('#plus').click(
function( event ){
    var scale = 150/100;
    var pos = $('#Container img').offset();
    var clickX = event.pageX - pos.left;
    var clickY = event.pageY - pos.top;
    var container = $('#Container img').parent().get(0);

    $('#Container img').css({
        width: this.width*scale,
        height: this.height*scale
    });

    container.scrollLeft = ($(container).width() / -2 ) + clickX * scale;
    container.scrollTop = ($(container).height() / -2 ) + clickY * scale;
}
);

$('#minus').click(
function( event ){
    var scale = 100/150;
    var pos = $('#Container img').offset();
    var clickX = event.pageX - pos.left;
    var clickY = event.pageY - pos.top;
    var container = $('#Container img').parent().get(0);

    $('#Container img').css({
        width: this.width*scale,
        height: this.height*scale
    });

    container.scrollLeft = ($(container).width() / -2 ) + clickX * scale;
    container.scrollTop = ($(container).height() / -2 ) + clickY * scale;
}
);