对Image画布上的图片进行边缘搜索，例如画布上有“123”的文字，可对文字进行挖空形成轮廓字，当然，最后数据编码可由你自己定了；-right on the edge Photo Search, such as canvas "123" language, be right words for the hollowing out the word outline form, of course, the final data coding can be determined