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Implementation Run Length Smoothing Algorithm in C++

asked 2014-02-06 09:29:49 -0500

vsay gravatar image

updated 2014-02-07 10:39:50 -0500

berak gravatar image

This is my old question related to RLSA in C++, but I havent got any help yet.

I tried to implement the code from Matlab to C++

The description of this algorithm :

http://crblpocr.blogspot.fr/2007/06/run-length-smoothing-algorithm-rlsa.html http://crblpocr.blogspot.fr/2007/06/determination-of-run-length-smoothing.html

There is RLSA implementation in Matlab by this thread :

http://mathworks.cn/matlabcentral/newsreader/view_thread/318198

MatLabCode

 hor_thresh=20;
zeros_count=0;
one_flag=0;
hor_image=image;
for i=1:m
    for j=1:n
        if(image(i,j)==1)
            if(one_flag==1)
                if(zeros_count<=hor_thresh)
                    hor_image(i,j-zeros_count:j-1)=1;
                else
                    one_flag=0;
                end
                zeros_count=0;
            end
            one_flag=1;
        else 
            if(one_flag==1)
                zeros_count=zeros_count+1;
            end
        end
    end
end

I tried to implement in C++ Code

    int hor_thres = 22;
                int one_count = 0;
                int zero_flag = 0;
                Mat tmpImg = Mat(Img.size(), CV_8UC1, Scalar(0, 0, 0));
                for (int j = 0; j<Img.rows; j++){
                    for (int i = 0; i<Img.cols; j++){
                        if (Img.at<uchar>(j, i) == 0)
                        {
                            if (zero_flag == 1)
                            {
                                if (one_count <= hor_thres)
                                {           
                                    tmpText(cv::Range(j - zero_count, j), cv::Range(i, i+1)).setTo(cv::Scalar::all(255));
// I want to do the same thing in Matlab as this  image(i,j-one_count:j-1)=0;
                                }
                                else
                                {
                                    zero_flag = 1;
                                }
                                one_count = 0;
                            }
                            zero_flag = 1;
                        }
                        else
                        {
                            if (zero_flag == 1)
                            {
                                one_count = one_count + 1;
                            }
                        }
                    }
                }

This time no error but the result is not expected ..

The issue is the way i want to write c++ code the same thing as

Matlab

tmpImg(i,j-one_count:j-1)=0;

C++

tmpText(cv::Range(j - zero_count, j), cv::Range(i, i+1)).setTo(cv::Scalar::all(255));

Anyidea???

Another thing is in Matlab the index start from 1 while C++ start from 0.

Thank

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answered 2014-02-10 08:30:33 -0500

Luca gravatar image

Well, regarding the index start problem, you just have to shift everything in order to make it work I think. As for the setting to 0 the matrix, I think you could use the Rect class:

tmpText(Rect(i,j-zero_count,zero_count-1,1)).setTo(0);

or something like this, where you specify starting position, width and height.

In any case, in what way the result is not as expected?

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Comments

@Luca Thank you, i already fix the issue, Just like you said I have some problems with indexs. However, I still not satify with the implementation since I only use nested loop rather than access in matrice way. what you think?

vsay gravatar imagevsay ( 2014-02-11 02:36:10 -0500 )edit

Sorry for the huge delay :P I'm not sure that you can avoid these loops! In any case, you could use pointers to access the Mat elements instead of the at<>() function!

uchar* p = Mat.data; int pos = j*Img.Cols + i; if(p[pos]==0) [...]

Luca gravatar imageLuca ( 2014-04-01 06:09:17 -0500 )edit
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Asked: 2014-02-06 09:29:49 -0500

Seen: 2,182 times

Last updated: Feb 10 '14