Difficulty in applying huffman encoding for image compression

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Nidhi Kumari 2018-10-9

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评论： Walter Roberson 2018-10-14

I got the given code to apply Huffman Encoding for image compression. But i am getting the error-

Error using huffmandict (line 71)
The symbol input must be a vector
Error in new (line 5)
[dict,avglen]=huffmandict(symbols,p)

The code is:

A=imread('xyz.jpg');
[symbols,p]=hist(A,double(unique(A)))
p=p/sum(p)
[dict,avglen]=huffmandict(symbols,p)
comp=huffmanenco(A,dict)

Help me as i am new to all these concepts.

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回答（2 个）

KALYAN ACHARJYA 2018-10-10

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编辑：KALYAN ACHARJYA 2018-10-10

在 MATLAB Online 中打开

When I have tested your code with the test image, both symbols and p have different sizes (see in the attached image) Read the documentation about huffmandict Clearly mentioned that-

The length of p must equal the length of symbols.

-------------------------------------------------------------------------------------------------------------------------------------------- Updated Answer

I have suspected another issue if you consider any 1 D array, the following code is working (Note that an image is 2D)

%A=double(imread('test.jpg'));
p=[.5 .125 .125 .125 .0625 .0625];
A=randsrc(100,1,[1:6; p]);
%[symbols,p]=hist(A,double(unique(A)));
[p,symbols]=hist(A,double(unique(A))); 
p=p/sum(p);
[dict,avglen]=huffmandict(symbols,p);
comp=huffmanenco(A,dict);