MATLAB: How to get the both uncontiguous objects in an image as just an object

Question

i want to loop a word in image, so that i can take every character in that image. but if i use the third dimension of bwlabel as my limit loop, the character like "i" will assume as 2 characters. because it has 2 uncontiguous object in that image. i think i have found how to get all characters of "Nick" by cropped those character automatically. but i confuse how to loop it so i can take every character and compare them with my training data.

Thanks before.

Answer 1

Try this:

clc;    % Clear the command window.
close all;  % Close all figures (except those of imtool.)
clear;  % Erase all existing variables. Or clearvars if you want.
workspace;  % Make sure the workspace panel is showing.
format long g;
format compact;
fontSize = 20;
grayImage =imread('Adok_karo1_biner.jpg');
% Show image
figure(1)
h1 = subplot(4, 12, 1:12);
imshow(grayImage);
impixelinfo
title('INPUT IMAGE WITH NOISE')
%% Convert to gray scale
if size(grayImage, 3) == 3 % RGB image
	grayImage=rgb2gray(grayImage);
end
%% Convert to binary image
threshold = graythresh(grayImage);
binaryImage = im2bw(grayImage, threshold);
% Remove all object containing fewer than 15 pixels
binaryImage = bwareaopen(binaryImage,15);
imshow(binaryImage);
axis('image', 'on'); % Display tick marks.
title('Binary Image', 'FontSize', fontSize);
% Find horizontal profile
h2 = subplot(4, 12, 13:24);
horizontalProfile = sum(binaryImage, 1);
plot(horizontalProfile, 'b-');
title('Horizontal Profile', 'FontSize', fontSize);
grid on;
% Find dividing lines between the characters.
props = regionprops(horizontalProfile == 0, 'Centroid');
xyCentroids = [props.Centroid];
dividingLines = xyCentroids(1:2:end)
for k = 1 : length(dividingLines)
	thisX = dividingLines(k);
	line(h1, [thisX, thisX], ylim(h1), 'Color', 'r');
	line(h2, [thisX, thisX], ylim(h2), 'Color', 'r');
end
% Enlarge figure to full screen.
set(gcf, 'Units', 'Normalized', 'Outerposition', [0, 0.05, 1, 0.95]);
drawnow;
% Extract each letter.
fontSize = 12;
for k = 1 : length(dividingLines) - 1
	thisX = round(dividingLines(k));
	nextX = round(dividingLines(k+1));
	subplot(4, 12, 24 + k);
	thisLetter = binaryImage(:, thisX:nextX);
	imshow(thisLetter);
	caption = sprintf('Letter #%d', k);
	title(caption, 'FontSize', fontSize);
end
	

Note that if you have kerning, like with characters 3 and 5, this algorithm won't work and you will have to do a little more work, like label the sub image and if there are two blobs, find their centroids. If there centroids are horizontally separated, then they're two kerned characters and you can nsplit them apart with ismember(). If the centroids are vertically aligned or close to it, then you might consider it as one character that has two parts like an i or j.