How can i delete a selected portion in an image and then paint it green?

I am doing a work on inpainting procedure, for that i am in requirement of a code that deletes a selected portion in an image and colors that region green i.e.(RGB =0 255 0)? Can anybody help

Answer 1

[Image Analyst]

For a freehand drawn method, see the full demo below:

% Demo to have the user freehand draw an irregular shape over a color image.
% Then it creates a new image where the drawn region is all green inside the region and untouched outside the region,

% Change the current folder to the folder of this m-file.
if(~isdeployed)
  cd(fileparts(which(mfilename)));
end
clc;  % Clear command window.
clear;  % Delete all variables.
close all;  % Close all figure windows except those created by imtool.
imtool close all;  % Close all figure windows created by imtool.
workspace;  % Make sure the workspace panel is showing.
fontSize = 16;

% Read in a standard MATLAB gray scale demo image.
folder = fileparts(which('onion.png')); % Determine where demo folder is (works with all versions).
baseFileName = 'onion.png';
% Get the full filename, with path prepended.
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.
  fullFileName = baseFileName; % No path this time.
  if ~exist(fullFileName, '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
rgbImage = imread(fullFileName);
imshow(rgbImage, []);
axis on;
title('Original Color Image', 'FontSize', fontSize);
set(gcf, 'Position', get(0,'Screensize')); % Maximize figure.

% Ask user to draw freehand mask.
message = sprintf('Left click and hold to begin drawing.\nSimply lift the mouse button to finish');
uiwait(msgbox(message));
hFH = imfreehand(); % Actual line of code to do the drawing.
% Create a binary image ("mask") from the ROI object.
binaryImage = hFH.createMask();
xy = hFH.getPosition;

% Now make it smaller so we can show more images.
subplot(2, 2, 1);
imshow(rgbImage, []);
axis on;
drawnow;
title('Original gray scale image', 'FontSize', fontSize);

% Display the freehand mask.
subplot(2, 2, 2);
imshow(binaryImage);
axis on;
title('Binary mask of the region', 'FontSize', fontSize);

% Get coordinates of the boundary of the freehand drawn region.
structBoundaries = bwboundaries(binaryImage);
xy=structBoundaries{1}; % Get n by 2 array of x,y coordinates.
x = xy(:, 2); % Columns.
y = xy(:, 1); % Rows.
subplot(2, 2, 1); % Plot over original image.
hold on; % Don't blow away the image.
plot(x, y, 'LineWidth', 2);
drawnow; % Force it to draw immediately.

% Burn region as green into image by setting it to [0, 255, 0] wherever the mask is true.
% Extract the individual red, green, and blue color channels.
redChannel = rgbImage(:, :, 1);
greenChannel = rgbImage(:, :, 2);
blueChannel = rgbImage(:, :, 3);
% Assign colors within each color channel individually.
redChannel(binaryImage) = 0;
greenChannel(binaryImage) = 255;
blueChannel(binaryImage) = 0;
% Recombine separate masked color channels into a single, true color RGB image.
maskedRgbImage = cat(3, redChannel, greenChannel, blueChannel);

burnedImage(binaryImage) = 255;
% Display the image with the mask "burned in."
subplot(2, 2, 3);
imshow(maskedRgbImage);
axis on;
caption = sprintf('Masked green inside region');
title(caption, 'FontSize', fontSize);

% Report results.
message = sprintf('Done with demo');
msgbox(message);

[Khaulah Zia]

i want to edit more than one regions in an image so how to change this code so i may select 2 or more ROI and replace those regions with a blob.

Thanks in advance.

[Khaulah Zia]

Actually i want to replace all the lights seen in an image by a white blob. I tried a for loop but in each loop the changes made in the previous loop is removed. At the end i am left with a single blob that i placed in the very last loop.

[Image Analyst]

You need to keep a cumulative mask and OR in the latest mask, like

thisMask = imfreehand(........
masterMask = masterMask | thisMask;

Make sure you set masterMask to false(rows, columns) before you start the loop.

masterMask = false(rows, columns);

Or you can initialize it in the loop on the first iteration

if k == 1
    masterMask = thisMask;
else
    masterMask = masterMask | thisMask;
end

Answer 2

[Geoff Hayes]

Sandeep - if you know the region of the region that needs to be coloured green (and if we assume that the region is rectangular) then you could try something like

 % create a black image
 myImg = zeros(400,400,3);

 % colour the top left-corner
 greenPatch           = zeros(200,200,3);
 greenPatch(:,:,2)    = 255;
 myImg(1:200,1:200,:) = greenPatch;

 % display the image
 image(uint8(myImg));

Note that we size the green patch to be such that it will fill the deleted portion of myImg.