//canvas.toDataURL('image/jpeg'), and convert to blob,blob is a File Object. but UC don't support

function dataURLtoBlob(dataurl) {

    var arr = dataurl.split(','), mime = arr[0].match(/:(.*?);/)[1],

        bstr = atob(arr[1]), n = bstr.length, u8arr = new Uint8Array(n);

    while (n--) u8arr[n] = bstr.charCodeAt(n);

    window.BlobBuilder = window.BlobBuilder || window.WebKitBlobBuilder || window.MozBlobBuilder || window.MSBlobBuilder;

    if (window.BlobBuilder) {

        var bb = new BlobBuilder();

        bb.append([u8arr]);

        return bb.getBlob(mime);

    } else return new Blob([u8arr], { type: mime });

}

//html image src convert to dataUrl

function imageToDataURL(url, callback, mime) {

    var canvas = document.createElement('canvas'),

        ctx = canvas.getContext('2d'),

        img = new Image;

    img.crossOrigin = 'Anonymous';

    img.onload = function () {

        canvas.height = img.height;

        canvas.width = img.width;

        ctx.drawImage(img, 0, 0);

        var dataURL = canvas.toDataURL(mime || 'image/jpeg');

        callback.call(this, dataURL);

        canvas = null;

    };

    img.src = url;

}