zoom out parallax hero

HTML

<header>
    <div class="bg-parallax bg-img1"></div>
   
   
</header>
 
    <div class="fullwidthtitle">                    	
<h1 class="content-title">Zoom Out <strong>Header</strong></h1>
</div>
<div class="gap"></div>

CSS

header {
    position: relative;
    height: 600px;
    overflow: hidden;
}


.logo {
    position: absolute;
    top: 50%;
    height: 100px;
    width: 100%;
    margin-top: -50px;
    background: url("https://upload.wikimedia.org/wikipedia/commons/7/73/Lion_waiting_in_Namibia.jpg") center center no-repeat;
}
.bg-parallax {   
    display: block;
    height: 100%;
    left: 0;
    position: absolute;
    top: 0;
    width: 100%;
    z-index: -5;
}

.bg-img1 {
      background: url("http://themes.cray.bg/amy/style-1/wp-content/uploads/sites/2/2014/07/artgerm-avatar-the-legend-of-2642996-1920x1333-1920x1080.jpg") center center no-repeat fixed;
   background-size: 100%;
   
}

.gap {
    height: 1000px;
}
.fullwidthtitle {
    margin-top: -2px;
    padding-bottom: 108px;
}
.fullwidthtitle .content-title{
   background: rgba(168, 113, 193, 1) none repeat scroll 0 0;
    box-sizing: border-box;
    color: #fff !important;
    padding: 37px 14px 39px;
    position: absolute;
    text-align: center;
    width: 100%;
    z-index: 6;

}

.content-title, .content-title a, .comment-reply-title, .h-style h2, h2.wpb_heading {
    font-family: Open Sans;
    font-style: normal;
    font-weight: 300;
}
.content-title {
    color: #777;
    display: block;
    font-size: 30px;
    line-height: 32px;
    margin-bottom: 0;
    padding-bottom: 10px;
}

JavaScript

var height = $('header').height();
//var logo = $('.logo');
var background = $('.bg-parallax');

$(window).on('scroll', function() {
    var scroll = $(this).scrollTop();

   // logo.css('transform', 'translateY(' + scroll / 0.7 + '%)');

    var backgroundSize = 200 - (0 - (height - scroll) / height * 10);
    backgroundSize = backgroundSize < 100 ? 100 : backgroundSize;
    background.css('background-size', backgroundSize + '%');
});