Row by Row character extraction

Question

I am working on handwritten character recognition from input image. Here is the code which extracts characters from input image

  %% Label connected components
          


        

Answer 1

Assumption: There is enough separation between rows of characters, such that there is at least one image row that is completely blank between two rows of characters.

Code

%%// Input binary image
BW = Ifill;

%%// Label connected blobs
[L,NUM] = bwlabel(BW);

%%// Find centroid points for each blob
cc = bwconncomp(BW);
stats = regionprops(cc, 'Centroid');
cent_rowcol = vertcat(stats.Centroid);

%%// Find transitions of characters starts and ends along the rows
trans1 = [0 ;diff(sum(BW,2)>0)]; 

%%// Find row midpoints for each row
row_midpts = (find(trans1==1) + find(trans1==-1))/2;

%%// Find the new labels based on row by row sorting
[~,row_id] = min(abs(bsxfun(@minus,cent_rowcol(:,2),row_midpts')),[],2); %%//'
[~,sortedInd] = sort((row_id-1)*size(BW,1)+cent_rowcol(:,1));

%%// Assign the new labels
L1 = zeros(size(L));
for k=1:numel(sortedInd)
    L1(L==sortedInd(k))=k;
end

%%// Testing: Show all the characters one by one row by row
figure,
for k=1:numel(sortedInd)
    imshow(L1==k);
    pause(0.2);
end

How to use the output, L1: You can get the first character with L1==1, second with L1==2 and so on, as shown in the Testing section at the end of code.