说明：  霍夫曼编码的基本方法是先对图像数据扫描一遍，计算出各种像素出现的概率，按概率的大小指定不同长度的唯一码字，由此得到一张该图像的霍夫曼码表。编码后的图像数据记录的是每个像素的码字，而码字与实际像素值的对应关系记录在码表中。 GUI实现
(The basic method of Huffman coding is to scan the image data first, calculate the probability of occurrence of various pixels, specify the unique codewords of different lengths according to the size of the probability, and get a Huffman code table of the image. The encoded image data records the codewords of each pixel, and the correspondence between the codewords and the actual pixel values is recorded in the code table. GUI implementation)