huffmanGUI1.zip_gui调用霍夫曼_霍夫曼

function CODE=huffman(p) %HUFFMAN Builds a variable-length Huffman code for a symbol source. % CODE=HUFFMAN(P) returns a Huffman code as binary string in % cell array CODE for input symbol probability vector P. Each word % in CODE corresponds to a symbol whose probability is at the % corresponding index of P. % % Based on huffman5 by Sean Danaher, University of northumbria, % Newcastle UK. Available at the MATLAB Central File Exchage: % Category General DSP in Signal Processing and Communications. % Check the input arguments for reasonableness error(nargchk(1,1,nargin)); if(ndims(p)~=2 | (min(size(p))>1) | ~isreal(p) | ~isnumeric(p)) error('P must be a real numeric vector.'); end % Global variable surviving all recursions of function 'makecode' global CODE CODE=cell(length(p),1); %Init the global cell array if length(p)>1 %When more than one symbol... p=p/sum(p); %Normalize the input probabilities s=reduce(p); %Do Huffman source symbol reductions makecode(s,[]); %Recursively generate the code else CODE={'1'}; %Else, trivial one symbol case! end %--------------------------------------------------------------------% function s=reduce(p) % Create a Huffman source reduction tree in a MATLAB cell structure % by performing source symbol reductions until there are only two % reduce symbols remaining s=cell(length(p),1); % Generate a strarting tree with symbol nodes 1, 2, 3, ...to % reference the symbol probabilities. for i=1:length(p) s{i}=i; end while size(s,1)>2 [p,i]=sort(p); %Sort the symbol probabilities p(2)=p(2)+p(1); %Merge the 2 lowest probabilities p(1)=[]; %and prune the lowest one s=s(i); %Reorder tree for new probabilities s{2}={s{1},s{2}}; %and merge & prune its nodes s(1)=[]; %to match the probabilities end %----------------------------------------------------------------------% function makecode(sc,codeword) % Scan the nodes of a Huffman source reduction tree recursively to % generate the indicated variable lenth code words. % Global variable surviving all recursive calls global CODE if isa(sc,'cell') makecode(sc{1},[codeword 0]); makecode(sc{2},[codeword 1]); else CODE{sc}=char('0'+codeword); end function y=mat2huff(x) %MAT2HUFF Huffman encodes a matrix. % Y=MAT2HUFF(X) Huffman encodes matrix X using symbol % probabilities in unit-width histogram bins between X's minimum % and maximum values. The encoded data is returned as a structure % Y: % Y.code The Huffman-encoded values of X, stored in % a uint16 vector. The other fields of Y contain % additional decoding information, including: % Y.min The minimum value of X plus 32768 % Y.size The size of X % Y.hist The histogram of X % If X is logical, uint8, uint16, uint32, int8, int16,or double, % with integer values, it can be input directly to MAT2HUFF. The % minimum value of X must be representable as an int16 % % If X is double with non-integer values --- for example, an image % with values between 0 and 1---first scale X to an appropriate % integer range before the call. For example, use Y= % MAT2HUFF(255*X) for 256 gray level encoding. % % NOTE: The number of Huffman code words is round(max(X(:)))- % round(min(X(:)))+1. You may need to scale input X to generate % codes of reasonable length. The maximum row or column dimension % of X is 65535. % % See also HUFFMAN2MAT if ndims(x)~=2 | ~isreal(x) | (~isnumeric(x) & ~islogical(x)) errror('X must be a 2-D real numeric or logical matrix'); end % Store the size of input x. y.size=uint32(size(x)); % Find the range of x values and store its minimum value biased % by+32768 as a UINT16. x=round(double(x)); xmin=min(x(:)); xmax=max(x(:)); pmin=double(int16(xmin)); pmin=uint16(pmin+32768); y.min=pmin; % Compute the input histogram between xmin and xmax with uint % width bins, scale to UINT16, and store. x=x(:)'; h=histc(x,xmin:xmax); if max(h)>65535 h=65535*h/max(h); end h=uint16(h); y.hist=h; % Code the input matrix and store the result. map=huffman(double(h)); %Make Huffman code map hx=map(x(:)-xmin+1); %Map image hx=char(hx)'; hx=hx(:)'; hx(hx==' ')=[]; %Remove blanks % ysize=ceil(length(hx)/16); %Compute encoded size % hx16=repmat('0',1,ysize*16); %pre-allocate modulo-16 vector % hx16(1:length(hx))=hx; %Make hx modulo-16 in length % hx16=reshape(hx16,16,ysize); %Reshape to 16-character words % hx16=hx16'-'0'; %Convert binary string to decimal % twos=pow2(15:-1:0); % y.code=uint16(sum(hx16.*twos(ones(ysize,1),:),2))'; y.code=hx; %test %本程序用于测试 f2=uint8([2 3 4 2;3 2 4 4;2 2 1 2;1 1 2 2]) whos('f2') c=huffman(hist(double(f2(:)),4)) h1f2=c(f2(:))' whos('h1f2') h2f2=char(h1f2)' whos('h2f2') h2f2=h2f2(:) h2f2(h2f2==' ')=[] whos('h2f2') h3f2=mat2huff(f2) whos('h3f2') hcode=h3f2.code whos('hcode') dec2bin(hcode) f=imread('Tracy.tif'); c=mat2huff(f); cr1=imratio(f,c) save SqueezeTracy c; cr2=imratio('Tracy.tif','SqueezeTracy.mat')