scroll-blur

HTML

<div class="scroll-space">
  <div class="blur blue">
  ぼかしが外れる
  </div>
</div>

SCSS

.scroll-space{
  box-sizing: border-box;
  padding-top: 300px;
  height: 700px;
  color: #fff;
  .blue{
    background: #77BBCF;
    width: 200px;
    height: 200px;
    padding: 30px;
    margin: 0 auto 50px;
  }
}
.blur{
    transition: all 0.5s;
    filter: blur(10px);
    &.scrollin{
      filter: blur(0);
    }
}

JavaScript

$(window).scroll(function (){
	$('.blur').each(function(){
		var elemPos = $(this).offset().top,
		scroll = $(window).scrollTop(),
		windowHeight = $(window).height();

			if (scroll > elemPos - windowHeight + 150){
				$(this).addClass('scrollin');
			}
	});
});