Huffman编码(哈夫曼编码)的Matlab实现

1、clea r allf printf ( Re a ding data、)d ata= imreadC camera man、tif)；da t a=uin t 8 (da t a) ;%读入数据，井将数据限制为u i n t 8fprintfC Done!n)%编码压缩fprintf pre s sing da t a、)：z i pp e d, info = n orm 2 huff (data)：fprintfC D one!n )%解压缩fp rin t f (* pressing data、)；u nzi p ped=h u ff 2 n o r m(zi p ped, in f 0

2、 )；f p r intf ( Done!n* )%测试就能否无失貞.isOK=i s e qua 1 (data(:)unz i pp ed(：)%显示压缩效果whos da t a z ippe d u n z i ppedfun c ti 0 n zi pp ed, info =norm2 h u f f ( v e c t or)if isa( Y ect o r, uint 8 *)er r or C i npu tar gume n t must be a uint 8 vector*)endvecto r =ve c t o r (:)：%将输入向量转换为行向量f=freq u

3、en c y (vec t or);%讣算个元素出现猖概率sirabo I s=fi n d (f=0);f=f(simbols);%W元素按出现得概率排列f, s 0 rti n d ex = s ot (f )：simbols = simbols( s ortindex):%产生码字 ge n e r ate the c odeword as the 5 2 bi t s of a do u bl elen= 1 e ng t h( s imb o Is);s i mb 0 ls_in d ex=num2cell (1: len);c odew 0rd_tmp= c elKle n , 1

4、 )：wh i le le n g t h ( f )1,ind exl= s imb o ls_index；index 2 =simb o 1 s _in d ex 2 ;codeword_tm p (i n dexl)=a d dnod e( c odeword_tmp (ind e xl) .u i n t8(0); c 0 d e w 0 rd_ t mp( ind ex2) = a ddno d e (co d e word_tm p (index 2 ), u i ntS (1 )：f=sum (f(1:2) fC3：end)；simbols_in d e x= i n d e x

5、 1 i n d e x2 simb o ls_ i ndex (3：e n d );%将数据重新排列，就是两个右点得频率尽量与前一个iT点得频率想肖r esort da t a in orde r to h av e two no d es w i th ! ov e r fr e que n cy asfirst toft so r ti n dex=sort(f):sim b ols_index=s i mbols_index(so r tindex):end$对应相应得元素与码字codew ord =cell( 2 56 :1);c odew 0 r d (sim b ols)=cod

6、ew o rd_tmp：%讣算总得字符串长度len=0：for index=l： length (vector) le n =1 e n+ 1 ength (codew ord doubl e (vector (index) )+1): end%产生01序列st r ing=repraa t (u i n t8(0) I en);poin t er= I :for inde x =1:1 e ngth(vect or),co d e=cod eworddou b 1 e(v e ct o r (inde x )+1;le n =length(co de);strin s (pointer+(0

7、 ：len-l) =code;poin t e r=poin t er+len：en d%如果需要，加零len= 1 ength ( s tring);p ad=8-mod (1 e n, 8);辻 pad 0 ,s t ring= s tring u in t 8(zeros(1 , pad);end财呆存实际有用得码字cod e wo r d=co d ew o rd (simbo 1 s);c ode I en=z e r o s (s i ze (codewor d );weigh t s=2、* (0:23);max c ode I e n= 0 ;1 e nm a s c od e

8、 1 e n,max cod e le n =len：n d1 e n0rc 0 de=sum(w e ig li t s ( codeword index =1)： cod e =bitset(cod e , le n +1);cod eword i nd ex =code：co d ele n (ind e x) =len;e iffo r ind ex 1; length ( cod ew ord), len=lengt h (cod e wordi n de x ); ifen dend co d eword= code wor d :%汁算压缩后得向量co ls= I eng t h

9、( s tri n g) / 8 ；s t r i ng= r eshape (strin g , 8, co 1 s);weights=2、* ( 0 : 7 );zip p e d = U intS (weights*d o u b 1 e (st ring)：%存储一个稀疏矩阵h uf f c 0 des=sp arse (1, 1);% init s p arse ma t r ixfor in d e x=l： nu me 1 ( c odeword),huffcod e s( c o dewo r d (ind e x),1 ) =s i m b ols (index):end瓯产

10、生信息结构体i nfox pad = pad ;info、rati o =cols、/leng t h(v e c tor):i n fox 1 en g th=l e ngth(vec t or);info, max c od e len=maxc o de 1 en；fun c t i 0 n codewor d _new=a d dno d e (co d eword_old, item)codew ord _ne w=cell ( s iz e (cod e word_ol d )：for index=l；lens t hCcodewor d _old),c 0 d e w 0 rd_

11、newin dex=Eitemcod ewo r d _oldi n de x ;endfu n c t ion v e c t or=huf f 2norm (zipped, info)%HVFF2X0RI Huffman 解码器%IIVFF2N0RM(X, INFO)根据倚息体结构info返回向星zipped得解码结果%矩阵参数以X(：)形成输入i f 2 i S a ( Z i P ped, uintS*).error ( i n pu t a r gumen t mus t be a uintS vector)end%产生01序列1 e n=l e ngth(zi p p ed);st

12、r i ng=repma t (uint 8 (0) ,1, len * 8 )；b it i n dex= 1 :8;for i n d e s+1： I en,s t r in s (b i tindes+g、* (ind e x -1) =uint8( b itget ( z ipped(index), bitind ex);end%调整字符串st r ing= I 0 gica 1 (st r ing (:)； % remove 0 padd i n g1 e n =lengt h ( s t ring);%解码weig h t s =2、* (0:51)：V ecto r =re p

13、 mat (uintS ( 0 ) , 1 , in f o, length);vec t orind e x=l;c 0 deinde x =1：c 0 de=O;for i n d ex=l： le n ,code=bit s et(coder cod e i n des, s t r i ng (ind ex); codein d e x=c o de i n d ex+ 1 ;byte=dec o de ( b i t set ( c o de, codei n dex), i n f o)： if by t e0- %V e ctor ( V ector i n d ex) =byte-l;cod ei n d e x= 1 :code = 0;vecto r i n d e X = V ect o rindex+ 1 ;endendfu n Ct i 0 n b yt e =d e code (code, i nfo)b y te=in f o、huf f cod e s (code);func t ion f=frequ e ncy (v e ct o r )幣FREQUENCY计算元素出现概率I fisa(