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Difficulty in applying huffman encoding for image compression
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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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Answers (2)
KALYAN ACHARJYA
on 10 Oct 2018
Edited: KALYAN ACHARJYA
on 10 Oct 2018
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.
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/197492/image.png)
-------------------------------------------------------------------------------------------------------------------------------------------- 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);
3 Comments
KALYAN ACHARJYA
on 10 Oct 2018
Edited: KALYAN ACHARJYA
on 10 Oct 2018
I have updated the answer, please check.
Walter Roberson
on 10 Oct 2018
[symbols,p] = hist(A(:), double(unique(A)));
6 Comments
Walter Roberson
on 14 Oct 2018
The output is not an image: it is a double vector containing the values 0 and 1.
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