haw can i remove backgroud using global threshold

On May 2, 12:10=A0pm, leila <leeeila12...@live.fr> wrote:
> haw can i remove backgroud using global threshold

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If it's even possible, you'd do something like this:


clc;    % Clear the command window.
close all;  % Close all figures (except those of imtool.)
imtool close all;  % Close all imtool figures.
clear;  % Erase all existing variables.
workspace;  % Make sure the workspace panel is showing.

% Change the current folder to the folder of this m-file.
% (The line of code below is from Brett Shoelson of The Mathworks.)
if(~isdeployed)
	cd(fileparts(which(mfilename)));
end
% Read in standard MATLAB grayscale demo image.
grayImage =3D imread('cameraman.tif');
subplot(2, 2, 1);
imshow(grayImage, []);
title('Original Grayscale Image');
set(gcf, 'Position', get(0,'Screensize')); % Enlarge figure to full
screen.

thresholdValue =3D 150;
backgroundImage =3D grayImage > thresholdValue;  % or you can use >
subplot(2, 2, 2);
imshow(backgroundImage, []);
title('Binary Image of Background');

grayImage(backgroundImage) =3D 0; % or whatever value you want.
subplot(2, 2, 3);
imshow(grayImage, []);
title('Original with black background');

%-------------------- end of code --------------------------------

See this demo for another example:
http://www.mathworks.com/matlabcentral/fileexchange/25157

Sometimes the background cannot be identified by a global threshold.