canvas图片base64编码后，ajax提交到后台

var imgData = canvas.toDataURL("image/png");
var data = imgData.substr(22);

$.post('Gen',
{ 'data': data, 'remark': $('remark').val() }
,function(success) {

$('#img1').src('data:image/jpeg;base64,' + success);

}
);

string inputStr = data;
byte[] arr = Convert.FromBase64String(inputStr);
MemoryStream ms = new MemoryStream(arr);
Bitmap bmps = new Bitmap(ms);