CODEWITHSUNDEEP
matlabimage-processing
Ahmed Amin
Ahmed Amin

Reputation: 5

How can I extract text from image respecting the distance between words?

I am trying to extract text from an image of printed text. Along with the text itself, I am interested in detecting the spaces between the words as well. The spaces between words are not consistent (deliberate) and that is something I want detected.

To achieved this I first had to extract the text lines. I achieved that using the projection profile code attached (code copied from one of the answers by ImageAnalyst). enter image description here

One way I thought of achieving this was by counting the number of white pixels between the words, if I know the number of pixels taken by a single space (say n), I could just determine the number of spaces by dividing the white pixels between the words by this 'n' to get the number of spaces.

I tried that but it did not go as planned, the results are very conflicting, even when compared against known ground truth values. Determining a baseline of every text line is proving to be difficult, for a single space between two words I am getting different pixel count. This is because as counting the white pixels from letter d to b is different from counting the white pixels from c to s (the white pixels within the curve of c is also sometimes counted.)

Any guidance or suggestions would be greatly appreciated.

Thank you

code I used : 

clc;  
close all;  
clear;  
fontSize = 16; 
img = imread('Lines.png');

[rows, columns, dim] = size(img);
if dim > 1  
    grayImage = img(:, :, 2);
end

% Display the original gray scale image.
subplot(3, 3, 1);
imshow(grayImage, []);
title('Original image', 'FontSize', fontSize);
axis on;

set(gcf, 'Units', 'Normalized', 'OuterPosition', [0 0 1 1]); % Enlarge figure to full screen.

% Threshold the image.
binaryImage = grayImage < 210;  

% Get rid of small areaas of 14 pixels or less
binaryImage = ~bwareaopen(binaryImage, 15);
subplot(2, 3, 2);
imshow(binaryImage);
title('Binary Image', 'FontSize', fontSize);
axis on;

% Vertical Profile
verticalProfile = sum(binaryImage, 2); 
subplot(3, 3, [2 3]);
plot(verticalProfile, 'b');
grid on;
title('Vertical Profile', 'FontSize', fontSize);

rowsWithText = verticalProfile < 600;  

% Find top and bottom lines
topLines = find(diff(rowsWithText) == 1);
bottomLines = find(diff(rowsWithText) == -1);

for j = 1 : length(topLines) 
    topRow = topLines(j);
    bottomRow = bottomLines(j);
    thisLine = binaryImage(topRow:bottomRow, :);
    subplot(3, 3, [4 5 6]);
    imshow(thisLine, []);
    axis on;
    caption = sprintf('Line %d of the text', j);
    title(caption, 'FontSize', fontSize);

    % Horizontal profile
    horizontalProfile = sum(thisLine, 1);
    subplot(3, 3, [7 8 9]);
    plot(horizontalProfile);
    grid on;
    caption = sprintf('Horizontal Profile of Line %d of the text', j);
    title(caption, 'FontSize', fontSize);

    promptMessage = sprintf('lines %d', j);
    titleBarCaption = 'Continue?';
    button = questdlg(promptMessage, titleBarCaption, 'Continue', 'Cancel', 'Continue');
    if strcmpi(button, 'Cancel')
        return;
    end  
end
msgbox('Done!');

picture : Image of my program

Upvotes: 1

Views: 167

Answers (1)

verbatross
verbatross

Reputation: 607

Try playing around with something like this:

% define min length of gap between words; play around with this value
min_gap_length = 5;

% define wordStarts/wordEnds like you've defined topLines/bottomLines
wordStarts = find(diff(horizontalProfile) == -1);
wordEnds = find(diff(horizontalProfile) == 1);
if wordStarts(1) > wordEnds(1)
    wordStarts = [1, wordStarts];
end
if wordEnds(end) < wordStarts(end)
    wordEnds = [wordEnds, length(horizontalProfile)];
end

% restrict wordStarts/wordEnds to gaps of over min_gap_length
I = wordStarts(2:end) - wordEnds(1:end-1) > min_gap_length;
wordStarts = wordStarts([true, I]);
wordEnds = wordEnds([I, true]);

Upvotes: 1

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