how to get horizontal projection of histogram of an binary image ?and based on that how to segment of each line in the image? please suggest me

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>> this is my ZjSqKcW.jpg and on the bases of this image i want the horizontal projection of histogram like g.png and after the histogram i want the segmentation of each line.how to do please suggest

Answer 1

[Alessandro Masullo]

Given your image im, you can binarize it with im2bw:

   bw = 1-im2bw(image);

The horizontal histogram (I guess) is the sum of the object in the horizontal direction, which is

   h = sum(bw,2)

You can then plot it with:

   figure
   plot(sum(bw,2),1:size(bw,1))

Which gives you the image attached.

The segmentation could be performed with findpeaks.

[ayushi]

its not showing histogram of the image in the axes there is only a white box on the gui axes,so on the bases of the histogram i can segment the all 4 lines of the image ZjSqKcW.jpg i mentioned earlier in previous question,as where there is no white ixels in row the each line can be devided or segmented for further vertical projection to segment words from the image. here

Iedge2= 1-im2bw(Binary image);
the code line i tried to display the histogram is as follows:

h = sum(Iedge2,2);
  imshow(plot(h,1:size(Iedge2,1)),'Parent',handles.axes2); 
  title('Horzontal HISTOGRAM OF IMAGE')

[Alessandro Masullo]

Why are you using imshow of plot? Just use plot.

[ayushi]

when using following code i am getting the horizontal histogram on the axes but sir please tell me how to segment each lines of the given image ZjSqKcW.jpg according to the horizontal histogram.

h = sum(Iedge2,2);
  plot(sum(Iedge2,2),1:size(Iedge2,1),'Parent',handles.axes2)
  title('HISTOGRAM OF DILATED IMAGE')

[Image Analyst]

Threshold it and then use regionprops(labeledImage, 'PixelIdxList') to find where each line starts and stops (what row indexes), or what rows have text in them.

[ayushi]

sir will you please explain it with the help of example i tried the following code but its not working properly and also i am not able to detect where is the error in this:

   %DESKEWING
   % Find the coordinates of all the pixels
  [y, x] = find(Iedge2);
  % Fit them to a line
  coefficients = polyfit(x, y, 1);
  % Get a line from the left to the right
  xEnds = [1, columns];
  yEnds = polyval(coefficients, xEnds);
  hold on;
  line(xEnds, yEnds, 'Color', 'r');

% Get the angle
angle = atand((yEnds(2) - yEnds(1)) / (xEnds(2) - xEnds(1)));
rotatedImage = imrotate(Iedge2, angle);
% Display the rotated image.
subplot(2, 2, 4);
imshow(rotatedImage, [],'Parent',handles.axes2);
title('Binary Image', 'FontSize', 10);
%regionprops to get all the BoundingBoxes form your lines
stats=regionprops(rotatedImage,'BoundingBox');
figure, imshow(rotatedImage)
BoundingBoxes=struct2cell(stats);
BoundingBoxes=cell2mat(BoundingBoxes'); % making it into an array
[~,ind]=sort(BoundingBoxes(:,2)); % sorting it to y
BoundingBoxes=BoundingBoxes(ind,:); % apply the sorted vector 

   lineNr=8;
  imshow(original(BoundingBoxes(2,lineNr):...
  BoundingBoxes(2,lineNr)+BoundingBoxes(4,lineNr),...
  BoundingBoxes(1,lineNr):BoundingBoxes(1,lineNr)+BoundingBoxes(3,lineNr)  ))