i am working on Image Compression Using Run Length Encoding

Question

juveria fatima 2018-3-28

1
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/391187-i-am-working-on-image-compression-using-run-length-encoding

评论： Walter Roberson 2024-6-16

am getting error in scanning in zigzag the error is as follows

Undefined function or variable 'toZigzag'.
Error in rlc_haar (line 21)
ImageArray=toZigzag(QuantizedImage);

plese help me

%%Matlab code for Image Compression Using Run Length Encoding
      clc;
      clear;
      close all;
      %%Set Quantization Parameter
      quantizedvalue=10;
      %%Read Input Image
      InputImage=imread('cameraman.tif');
      [row col p]=size(InputImage);
      %%Wavelet Decomposition 
      [LL LH HL HH]=dwt2(InputImage,'haar'); 
      WaveletDecomposeImage=[LL,LH;HL,HH]; 
      imshow(WaveletDecomposeImage,[]);
      %uniform quantization
      QuantizedImage= WaveletDecomposeImage/quantizedvalue;
      QuantizedImage= round(QuantizedImage);
      % Convert the Two dimensional Image to a one dimensional Array using ZigZag Scanning
      ImageArray=toZigzag(QuantizedImage);
      %%Run Length Encoding
      j=1;
      a=length(ImageArray);
      count=0;
      for n=1:a
       b=ImageArray(n);
       if n==a
       count=count+1;
       c(j)=count;
       s(j)=ImageArray(n);
       elseif ImageArray(n)==ImageArray(n+1)
       count=count+1;
       elseif ImageArray(n)==b
       count=count+1;
       c(j)=count;
       s(j)=ImageArray(n);
       j=j+1;
       count=0;
       end
      end
      %%Calculation Bit Cost
      InputBitcost=row*col*8;
      InputBitcost=(InputBitcost);
      c1=length(c);
      s1=length(s);
      OutputBitcost= (c1*8)+(s1*8);
      OutputBitcost=(OutputBitcost);
      %%Run Length Decoding g=length(s);
      j=1;
      l=1;
      for i=1:g
       v(l)=s(j);
       if c(j)~=0
       w=l+c(j)-1;
       for p=l:w
       v(l)=s(j);
       l=l+1;
       end
       end
       j=j+1;
      end
      ReconstructedImageArray=v;
      %%Inverse ZigZag
      ReconstructedImage=invZigzag(ReconstructedImageArray)
      %%Inverse Quantization
      ReconstructedImage=ReconstructedImage*quantizedvalue;

4 个评论
显示 2更早的评论隐藏 2更早的评论

karthika 2024-6-16

So can't we apply zigzag scanning in rle??

Walter Roberson 2024-6-16

@karthika

Sure, you can combine zigzag scanning with RLE. The resulting code would be unclear and probably would be difficult to maintain. It would probably be much more effective to have a zigzag scan function separate from the RLE function.

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Walter Roberson 2018-3-28

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/391187-i-am-working-on-image-compression-using-run-length-encoding#answer_312386

That code is from https://www.pantechsolutions.net/image-processing-projects/image-compression-using-run-length-encoding and has been posted without attribution.

The complete code is being sold for 2000 rupees. It is not our place to duplicate commercial code for free.

Code for RLE encoding with zigzag scan has been posted a few times on MATLAB Answers -- zigzag scan is used by JPEG encoding, so there have been a number of posts of the code for that.