根据css 让背景图变灰色

<span class="pattern  left">
  <img src="../static/image/download_pattern_left.png" data-cfsrc="../static/image/download_pattern_left.png"/></span> 

css

/* 使2个背景图变灰色*/

.pattern{

    -webkit-filter: grayscale(100%);

    -moz-filter: grayscale(100%);

    -ms-filter:grayscale(100%);

    -o-filter: grayscale(100%);

    filter: grayscale(100%);

    filter:gray;

}