Huffman coding.rar_teacherm55_哈夫曼编码_图像压缩_编码 压缩

import java.awt.image.BufferedImage; import java.io.File; import javax.imageio.ImageIO; import java.util.Map.Entry; import java.util.*; public class Huffman_coding{ String allCode =""; public int[] readImage(String imageUrl) throws Exception{ int[] rgb = new int[3]; File file = new File(imageUrl); BufferedImage image = ImageIO.read(file); try { image = ImageIO.read(file); } catch (Exception e) { e.printStackTrace(); } int width = image.getWidth(); int height = image.getHeight(); int[] pixelValue = new int[width*height]; int sum = 0; for (int i = 0; i < height; i++) { for (int j = 0; j < width; j++) { int pixel = image.getRGB(i, j); pixelValue[sum] = (pixel & 0xff0000) >> 16; rgb[0] = (pixel & 0xff0000) >> 16; sum = sum + 1; } } return pixelValue; } public List<Node> copyList(List<Node> list){ List<Node> newlist = new ArrayList<Node>(); for (Node node:list){ newlist.add(node); } return newlist; } public Node creatHuffmanTree(List<Node> nodeList){ List<Node> list = copyList(nodeList); while(list.size() > 1){ list.sort(Comparator.naturalOrder()); Node leftNode = list.get(0); list.remove(list.get(0)); Node rightNode = list.get(0); list.remove(list.get(0)); Node father = new Node(leftNode.value+rightNode.value); father.left = leftNode; father.right = rightNode; leftNode.father = father; rightNode.father = father; list.add(father); } System.out.println(list); return list.get(0); } /// public List<Node> creatNodes(List<Map.Entry<Integer,Integer>> list){ List<Node> nodelist = new ArrayList<Node>(); for (Map.Entry<Integer, Integer> mapping : list) { nodelist.add(new Node(mapping.getKey(),mapping.getValue())); } return nodelist; } /// public List<Map.Entry<Integer,Integer>> caculateRate(int[] pixelValue){ Map<Integer, Integer> map = new HashMap<Integer, Integer>(); int values= 0; for(int i = 0; i < pixelValue.length; i++){ if (!map.containsKey(pixelValue[i])){ map.put(pixelValue[i],1); } else{ values = map.get(pixelValue[i]); map.put(pixelValue[i],values+1); } } List<Map.Entry<Integer,Integer>> list = new ArrayList<Map.Entry<Integer,Integer>>(map.entrySet()); return list; } public Map<Integer,String> toEncoding(List<Node> list,Node root,int[] pixelValue){ Map<Integer,String> map = new HashMap<Integer,String>(); for(Node node: list){ String code = ""; Node node_Now = node; while(node_Now != root){ if(node_Now.isLeft()){ code = code + "0"; } else code = code + "1"; node_Now = node_Now.father; } code = invertString(code); map.put(node.key,code); } for(int i=0;i<pixelValue.length;i++){ allCode = allCode + map.get(pixelValue[i]); } System.out.println("编码后大小:"+allCode.length()+" bit"); System.out.println("编码:"+allCode); return map; } public int[] decoding(int[] pixelValue,Map<Integer,String> dictionary ){ String coding = ""; int j = 0; int[] decodingPixelValue = new int[pixelValue.length]; for(int i = 0;i<allCode.length();i++){ coding = coding + allCode.charAt(i); for (Map.Entry<Integer, String> entry : dictionary.entrySet()) { if(coding.equals(entry.getValue())){ decodingPixelValue[j] = entry.getKey(); j = j+1; coding = ""; } } } return decodingPixelValue; } public String invertString(String s){ String s1 = ""; for(int i = s.length()-1;i>=0;i--){ s1 = s1+s.charAt(i); } return s1; } /// public static void main(String[] args) throws Exception{ Map map = new HashMap(); Map dictionary = new HashMap(); List list = new ArrayList(); List<Node> nodeList = new ArrayList<Node>(); String url = "pig.bmp"; Huffman_coding hc = new Huffman_coding(); int[] pixelValue = hc.readImage(url); list = hc.caculateRate(pixelValue); nodeList = hc.creatNodes(list); Node root = hc.creatHuffmanTree(nodeList); dictionary = hc.toEncoding(nodeList,root,pixelValue); int[] decodingPixelValue = hc.decoding(pixelValue,dictionary); System.out.println("字典:"+dictionary); System.out.println("像素值:"+Arrays.toString(pixelValue)); System.out.println("解码后的像素值:"+Arrays.toString(decodingPixelValue)); } }