how to replace the color of the pixel with its neighborhood darkest pixel???

My images are not uniform.Every time image background color is going to be change.Here is the image.From this image i want to replace Google with orange color.

Answer 1

[Image Analyst]

Try this:

clc;    % Clear the command window.
close all;  % Close all figures (except those of imtool.)
workspace;  % Make sure the workspace panel is showing.
format long g;
format compact;
fontSize = 22;
% Read in a standard MATLAB color demo image.
folder = 'D:\Temporary Stuff';
baseFileName = '4545.png';
% Get the full filename, with path prepended.
fullFileName = fullfile(folder, baseFileName);
if ~exist(fullFileName, 'file')
  % Didn't find it there.  Check the search path for it.
  fullFileName = baseFileName; % No path this time.
  if ~exist(fullFileName, 'file')
    % Still didn't find it.  Alert user.
    errorMessage = sprintf('Error: %s does not exist.', fullFileName);
    uiwait(warndlg(errorMessage));
    return;
  end
end
rgbImage = imread(fullFileName);
% Get the dimensions of the image.  numberOfColorBands should be = 3.
[rows, columns, numberOfColorBands] = size(rgbImage);
% Display the original color image.
subplot(2, 2, 1);
imshow(rgbImage);
title('Original Color Image', 'FontSize', fontSize);
% Enlarge figure to full screen.
set(gcf, 'units','normalized','outerposition',[0 0 1 1]);

% Extract the individual red, green, and blue color channels.
redChannel = rgbImage(:, :, 1);
greenChannel = rgbImage(:, :, 2);
blueChannel = rgbImage(:, :, 3);

mask = redChannel < 200; % Letters
% Enlarge it a bit
mask = imdilate(mask, true(3));
subplot(2, 2, 2);
imshow(mask);
title('Mask for Letters', 'FontSize', fontSize);

% Get the mean RGB values
meanR = mean2(redChannel(~mask));
meanG = mean2(greenChannel(~mask));
meanB = mean2(blueChannel(~mask));

% Fill in letters with background.
redChannel(mask) = meanR;
greenChannel(mask) = meanG;
blueChannel(mask) = meanB;

% Recombine separate color channels into a single, true color RGB image.
rgbImage = cat(3, redChannel, greenChannel, blueChannel);
subplot(2, 2, 3);
imshow(rgbImage);
title('Letters are gone!', 'FontSize', fontSize);