拖放区缩略图宽度图像大小

如何更改上传图像的缩略图大小？我在我的javascript中尝试过thumbnailWidth:"350"，但是这不会增加缩略图大小，而缩略图只是看起来放大了。如何操作图像缩略图大小？

HTML:

<section id="create">
<form action="upload.php" class="dropzone" id="uploadphoto"></form>
</section>

CSS:

.dropzone {
position: relative;
border: 10px dotted #FFF;
border-radius: 20px;
color: white;
font: bold 24px/200px arial;
height: 400px;
margin: 100px auto;
text-align: center;
width: 400px;
}

.dropzone:hover {
border: 10px dotted #0C3;

.dropzone.dropped {
background: #222;
border: 10px dotted #444;
}

.dropzone.in {
width: 600px;
height: 200px;
line-height: 200px;
font-size: larger;
}

.dropzone img {
border-radius: 10px;
vertical-align: middle;
max-width: 95%;
max-height: 95%;
}

JavaScript：

Dropzone.options.uploadphoto = {
maxFilesize: 25, //MB
dictDefaultMessage: "Drag and Drop Posters    or click",
acceptedFiles: ".jpeg,.jpg,.png,.gif,.JPEG,.JPG,.PNG,.GIF,.pdf,.pub",
thumbnailWidth:"350",
accept: function(file, done) {
    console.log("uploaded"); //debuging the upload
    done();
},
init: function() {
 this.on("addedfile", function() {
  if (this.files[1]!=null){
    this.removeFile(this.files[0]);
       }
    });
  }
};

使用与配置选项中使用的相同值覆盖 CSS

.dropzone .dz-preview .dz-image {
  width: 250px;
  height: 250px;
}


Dropzone.options.myAwesomeDropzone = {
  ....
  thumbnailWidth: 250,
  thumbnailHeight: 250,
  ....
}

See the JS 小提琴在这里 https://jsfiddle.net/n3wwac7v/