$('#modalWindow').on('click', '#send', function () {
        $.ajax({
            type: "POST",
            url: "/Home/LoadImage",
            data: {
                "base64img": $('#autoPicture').attr('src')
            },
            success: function (data) {
                alert('Привет');
            },
            error: function (error) {
                alert(error.responseText);
            }
        });
    });

    $('#modalWindow').on('change', '#fileLoader', function () {
        ReadImageUrl(this);
    });

    function ReadImageUrl(input) {
        if (input.files && input.files[0]) {
            var reader = new FileReader();

            reader.readAsDataURL(input.files[0]);

            reader.onload = function (e) {
                $('#autoPicture').attr('src', e.target.result);
            }
        }
    }

[HttpPost]
        public ActionResult LoadImage(string base64img)
        {
            byte[] picture = Convert.FromBase64String(base64img);

            return View();
        }