Change the photo background to white

I have a RGB image of 256*256 pixels. How to copy RGB pixel to another image. Actually I want to convert background into pure white(255).So how do I do that task. Example image was attached.

Answer 1

[Image Analyst]

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;

% Get the base filename.
baseFileName = 'bottle.jpg'; % Assign the one on the button that they clicked on.
% Get the full filename, with path prepended.
folder = pwd; % Current folder
fullFileName = fullfile(folder, baseFileName);

% Check if file exists.
if ~exist(fullFileName, 'file')
  % File doesn't exist -- didn't find it there.  Check the search path for it.
  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
% Read in image.
originalImage = imread(fullFileName);
% Get the dimensions of the image.
% numberOfColorBands should be = 1.
[rows, columns, numberOfColorBands] = size(originalImage);
if numberOfColorBands > 1
  % It's not really gray scale like we expected - it's color.
  % Convert it to gray scale by taking only the blue channel.
  grayImage = min(originalImage, [], 3); % Take blue channel.
else
  % It's already grayscale
  grayImage = originalImage;
end
% Display the original image.
subplot(2, 3, 1);
imshow(originalImage);
axis on;
title('Original Image', 'FontSize', fontSize, 'Interpreter', 'None');
% Display the original image.
subplot(2, 3, 2);
imshow(grayImage, []);
axis on;
title('Gray Scale Image', 'FontSize', fontSize, 'Interpreter', 'None');
drawnow;

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

% Let's compute and display the histogram.
subplot(2, 3, 3);
histogram(grayImage);
xlim([0, 255]);
grid on;
title('Intensity Histogram of Gray Scale Image', 'FontSize', fontSize, 'Interpreter', 'None');
xlabel('Gray Level', 'FontSize', fontSize);
ylabel('Pixel Count', 'FontSize', fontSize);

% Need to get the background (light stuff) but not get any light stuff in the bottle.
% Threshold to find dark.
binaryImage = grayImage < 100;
% Extract the largest blob only
binaryImage = bwareafilt(binaryImage, 1);
% Fill any holes.
binaryImage = imfill(binaryImage, 'holes');
% Invert to get the background.
binaryImage = ~binaryImage;
% Display the binary image.
subplot(2, 3, 4);
imshow(binaryImage, []);
axis on;
title('Binary Background Image', 'FontSize', fontSize);

% Initialize a new output image.
outputImage = originalImage;
% Mask the background to be white by making a uint8 image of
% all 255 where the background is then adding, which will clip.
backgroundImage = repmat(uint8(255*binaryImage), [1,1,3]);
outputImage = outputImage + backgroundImage;

% Display the final output image.
subplot(2, 3, 5);
imshow(outputImage, []);
axis on;
title('All White Background Image', 'FontSize', fontSize);