Huffman编码的Matlab实现

1、clea r a 11f printf ( Re a ding d ata、)d ata= i m r ea d ( c a me r a marix tif)：da t a=uin t 8 (da t a) ;$读入数据，并将数据限制为u i n t 8f pri n t f (* Don e ! n)%编码压缩fprintf C pre s sing da t )；z i pp e d, info = n orm 2 huff (data);fprintf (1)one! n)%解压缩f p rin t f ( pressin g data、)；u nzi p ped=h u ff 2 n

2、 o r m(zi p ped, in f o ):f p r intf ( Done!n )%测试就是否无失真isOK=i s e q u a 1 (data(:), unz i p p ed(:)%显示压缩效果whos da t a z ippe d u n z i pped fun c ti o n zip p ed, info = nor m2 huff(vect or) ifisa( v ect o r, uint 8 *),er r or ( i npu tar gume n t must be a uint 8 vector)endvecto r =ve c t o r (:)%

3、将输入向量转换为行向量f=freq u en c y (vec t or);%汁算个元素出现得概率 simbo 1 s=fi n d (f=0);f二f (simbol s );%将元素按岀现得概率排列f, s o rti n d ex = s ot (f )：simbols = simbols( s ortindex):%产生码字 ge n e r ate the c odeword a s th e 5 2 bi t s of a d o u bl e len= 1 e ng t h( s imb o Is);s i mb ols_in d ex=num2cell (1:len);c od

4、ew ord_tmp= c ell(le n, 1)：wh i le le n g t h ( f )1,in d exl= s i mb o ls_index 1;index 2 =simb o 1 s _in d ex 2 ;codeword_tm p (i n dexl)=a d dno d e( c ode w ord_tm p (in d e xl) u i n t8(0); c o d e wo rd_ t mp( i nd e x 2 ) = a ddno d e (co d e word_tm p (index 2 ), u i nt8( 1 )：f=sum (f (1:2)

5、f (3:end):simbol s_in d ex二indexl inde x2 simb o ls_ i ndex (3:e nd);%将数据重新排列，就是两个节点得频率尽量与前一个节点得频率想当r esort da t a in orde r to h av e two no d es w i th 1 ow e r fr e que n cy afirst toft so r t in dex=sort (f):sim b ols_index=s i mbols_index(so r tindex);end玄对应相应得元素与码字codew ord =cell( 2 56 :1);c o

6、dew o r d (sim b ols) =codew o rd_tmp;%计算总得字符串长度len=0;for index二 1： length (vector) tle n =1 e n+ 1 ength (codew ord doubl e (vector (index )+1);end%产生01序列st r ing=repma t (u i n t8(0), 1, 1 en);poin t er= 1 :for inde x =1:1 e ngth (vect or),co d e=cod e wo rd d o u b 1 e(v e ct o r (inde x )+1;le n

7、 =length(co de);strin g (pointer+(0 :len-1) =code;poin t e r=poin t e r+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%保存实际有用得码字cod e wo r d=co d ew o rd (simbo 1 s);c ode 1 en=z e r o s (s i ze (codewor d );weigh t s=2 * (0:23);

8、max c ode 1 e n= 0 ;fo r in d ex 1 ： length ( c o d e w ord),len=lengt h (cod e wordi n de x );if 1 e nm a x c od e 1 e n,max cod e le n =len;e ndif len0,c o de=sum(w e ig h t s ( codeword index =1)：cod e =bitset (cod e , le n +1);codeword! in d ex二 code：co d ele n (ind e x)=len;en d end co deword 二

9、code w or d ：%计算压缩后得向星c o ls= 1 eng t h( s tri n g) / 8 ；s t r i ng= r eshape(strin g , 8, co I s);w eight s=2n(0:7);zip p e d = u int8 (weights*d o u b 1 e (s t rin g)：%存储一个稀疏矩阵h uf f c o des=sp a r s e(l, 1);% init s p arse ma t r ixfor in d e x=l： n u m e 1 ( c odeword),huff cod e s ( c o dewo r

10、d (ind e x),1 ) =s i m b ols (index);end%产生信息结构体i nfox pa d = p a d ;info、ratio 二cols、/leng t h(v e c tor):in 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 o 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

11、: len g t h(code wor d _old),c o d e w o rd_newin d e x = item co d ewo r d _oldi n de x ;endfu n c t ion v e c t or=huf f 2norm (zipped, info)%HUFF2N0RM Huffman 解码器%IIUFF2N0RM(X, INFO)根据信息体结构info返回向量zipped得解码结果%矩阵参数以x(：)形式输入i f i s a ( z i p ped, uint8) error ( i n pu t a r gumen t mus t be a uint8

12、 vector* )end%产生01序列1 e n=l e ngth(zi p ped);str i ng=repma t (uint 8 (0) , L len、* 8 )；b it i n dex= 1 :8;for i n d e x+1：1 en,s t r in g (b i tindex+8、* ( in d e x -1) =uint8 ( b itget ( z ipped(index), bitind ex);end%调整字符串st r ing= 1 o gica 1 (st r ing (：)： % r e m o ve 0 padd i n glen 二lengt h (

13、 s t ring);%解码weig h t s =2、 (0:51);v ecto r =re p mat (uintS ( 0 ) , 1 , in f o, length);vec t orin d e x=l;c o deinde x =1;：U a I / g 划一盼 pU2：(x ap u T) gjuinjoi o sa) urns = ( j+x p ut) j% 92： 0 =x a PUT 珂 :(JO ) OQA) q ) 2 U 二UQ(9 9 3 U 0) 1 b indoj= j pua(joiooa g 1 uIn b a q is n in iuoluuSj b n d ut )jojj a4( ,8)u I n ojo a a)stj iADNan&aiH% (j o io a a) Aou a nbjj=j uot)ounj :(spoo) s a poo j jnq、o j ui qi A q (oju i i a p o o) poo a p= a 1X q u o i io u nj puQ pun! I +XQpUTJ O 103 A = X p U I J OJOQA：0 = POD J I =xap