<input type="file" class="upload" capture="camera"  accept="image/*" onchange="angular.element(this).scope().uploadhead(this)" />

        $scope.uploadhead = function(file) {

            fileSelected(file);

        }

        function fileSelected(obj) {

            if (obj) {

                var file = obj.files[0];

                if (ImgCompress.checkType(file)) {

                    ImgCompress.getBase64(file, obj, getBase);

                }

            }

        }

        function getBase(data) {

            $("#myavatar").attr("src", data);

        }

        var ImgCompress = {

            checkType: function(file) {

                if (!file.type.match('image.*')) {

                    return false;

                } else {

                    return true;

                }

            },

            getBase64: function(file, obj, callBack) {

                var _this = this;

                _this.readFile(file, obj, callBack);

            },

            readFile: function(file, obj, callBack) {

                var _this = this;

                //读取文件

                if (window.FileReader) {

                    var fr = new FileReader();

                    fr.onloadend = function(e) {

                        //显示图片

                        var src = e.target.result;

                        //压缩图片获取base64编码

                        _this.compress(src, callBack);

                    };

                    fr.readAsDataURL(file);

                } else {

                    alert("请使用高版本浏览器！");

                }

            },

            compress: function(src, callBack) {

                var _this = this;

                var img = new Image();

                img.src = src;

                img.onload = function() {

                    //生成比例

                    var width = img.naturalWidth,

                        height = img.naturalHeight,

                        scale = width / height;

                    width = parseInt(750);

                    height = parseInt(width / scale);

                    //生成canvas

                    var $canvas = document.createElement("canvas");

                    var ctx = $canvas.getContext('2d');

                    $canvas.width = width;

                    $canvas.height = height;

                    //压缩

                    ctx.drawImage(img, 0, 0, width, height);
　　　　　　　　　　　　//这里转成jpeg，也可以不转

                    callBack($canvas.toDataURL('image/jpeg', 0.5));

                }

            }

        };