I Can not convert image to binary image !

Hi

I'm trying to convert this image to binary image

This is the code:

OriginalImage = imread('t1.jpg');
subplot(2,2,1);
imshow(OriginalImage);
g = rgb2gray(OriginalImage);
subplot(2,2,2);
imshow(g);
BW = im2bw(g);
subplot(2,2,3);
imshow(BW);

The background should be black but here is the result !!

Could you please help me !

Answer 1

[Image Analyst]

Use imbinarize() instead.

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 = 16;

%===============================================================================
% Read in a demo image.
folder = pwd;
baseFileName = 't9.jpg';
% Get the full filename, with path prepended.
fullFileName = fullfile(folder, baseFileName);
% Check if file exists.
if ~exist(fullFileName, 'file')
  % The file doesn't exist -- didn't find it there in that folder.  
  % Check the entire search path (other folders) for the file by stripping off the folder.
  fullFileNameOnSearchPath = baseFileName; % No path this time.
  if ~exist(fullFileNameOnSearchPath, 'file')
    % Still didn't find it.  Alert user.
    errorMessage = sprintf('Error: %s does not exist in the search path folders.', fullFileName);
    uiwait(warndlg(errorMessage));
    return;
  end
end
originalImage = imread(fullFileName);
% Display the image.
subplot(2, 2, 1);
imshow(originalImage, []);
title('Original Image', 'FontSize', fontSize, 'Interpreter', 'None');

% Get the dimensions of the image.  
% numberOfColorChannels should be = 1 for a gray scale image, and 3 for an RGB color image.
[rows, columns, numberOfColorChannels] = size(originalImage);
if numberOfColorChannels > 1
  % It's not really gray scale like we expected - it's color.
  % Use weighted sum of ALL channels to create a gray scale image.
  grayImage = rgb2gray(originalImage); 
  % ALTERNATE METHOD: Convert it to gray scale by taking only the green channel,
  % which in a typical snapshot will be the least noisy channel.
  % grayImage = grayImage(:, :, 2); % Take green channel.
else
  grayImage = rgbImage;  % Not really an RGB image.
end
% Display the image.
subplot(2, 2, 2);
imshow(grayImage);
title('Grayscale Image', 'FontSize', fontSize, 'Interpreter', 'None');

%------------------------------------------------------------------------------
% Set up figure properties:
% Enlarge figure to full screen.
set(gcf, 'Units', 'Normalized', 'OuterPosition', [0, 0.04, 1, 0.96]);
% Get rid of tool bar and pulldown menus that are along top of figure.
% set(gcf, 'Toolbar', 'none', 'Menu', 'none');
% Give a name to the title bar.
set(gcf, 'Name', 'Demo by ImageAnalyst', 'NumberTitle', 'Off') 

% Binarize the image.
binaryImage = imbinarize(grayImage);
% Display the image.
subplot(2, 2, 3);
imshow(binaryImage, []);
title('Binary Image', 'FontSize', fontSize, 'Interpreter', 'None');

[Han]

Thank you ..

I used imbinarize() but when I try this image is not working

[Image Analyst]

It does work in that it doesn't throw an error. Exactly what would you like for the output in this case of 3 different intensity ranges? imbinarize() divides the image into two ranges, not three. Perhaps you'd like multithresh() instead of imbinarize, or simply do it yourself:

binaryImage = grayImage ~= backgroundGrayLevel;