阅读Exif并获得Orientation问题

Question

我正试图从这样的exif数据中获取方向：Extract exif orientation

    var img = new Image();
    img.src = "data:image/jpeg;base64," + imgData;
    img.onload = function () {
        var canvas = document.createElement("canvas");

        canvas.width = img.width;
        canvas.height = img.height;

        var bin = atob(img.src.split(',')[1]);
        var exif = EXIF.readFromBinaryFile(new BinaryFile(bin));
        alert(exif.Orientation);
        alert(EXIF.getTag(imgData, "Orientation"));

然而它的所有警报都是未定义的......我不确定原因。

我在我的html文件中包含了exif.js和binaryajax.js，所以这不是问题