Sir . I have successfully cropped the upper region (in 5 coin) but couldn't crop lower region from the same image as I need to crop the image so to get center part only as high.

Answer 1

[Image Analyst]

Try this. Adapt as needed, like the percentage of the middle that you want.

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 = 16;

%===============================================================================
% Get the name of the image the user wants to use.
baseFileName = 'c3.jpg';
folder = pwd
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

%=======================================================================================
% Read in demo image.
rgbImage = imread(fullFileName);
% Get the dimensions of the image.
[rows, columns, numberOfColorChannels] = size(rgbImage)

% Display image.
subplot(3, 3, 1);
imshow(rgbImage, []);
axis on;
caption = sprintf('Original Color Image\n%s', baseFileName);
title(caption, 'FontSize', fontSize, 'Interpreter', 'None');
hp = impixelinfo(); % Set up status line to see values when you mouse over the image.

% Set up figure properties:
% Enlarge figure to full screen.
set(gcf, 'Units', 'Normalized', 'OuterPosition', [0 0.05 1 0.95]);
% 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;

% Find the max in all color channels.
mask = max(rgbImage, [], 3);

% Take the largest blob only, to get rid of noise.
% mask = bwareafilt(mask, 1);
% Fill any holes in it.
% mask = imfill(mask, 'holes');
% Let's assume it's supposed to be convex.  Make sure.
% mask = bwconvhull(mask);

% Display the image.
subplot(3, 3, 2);
histogram(mask);
% Binarize the image
mask = mask > 225;
% Keep only largest region then invert it to get the coin masks.
mask = ~bwareafilt(mask, 1);
% Fill holes.
mask = imfill(mask, 'holes');
% Get rid of blobs less than 1000 pixels.  There seems to be a few.
mask = bwareafilt(mask, [1000, inf]);
[labeledImage, numBlobs] = bwlabel(mask);
imshow(mask, []);
axis on;
title('Binary Image', 'FontSize', fontSize, 'Interpreter', 'None');
drawnow;

% Mask the image with the new, cleaned mask.
% Mask the image using bsxfun() function to multiply the mask by each channel individually.
maskedRgbImage = bsxfun(@times, rgbImage, cast(mask, 'like', rgbImage));

% Display the image.
subplot(3, 3, 3);
imshow(maskedRgbImage, []);
axis on;
title('Masked RGB Image', 'FontSize', fontSize, 'Interpreter', 'None');
drawnow;

% Get the equivalent bounding box.
props = regionprops(mask, 'BoundingBox', 'area');
allAreas = [props.Area]
plotNumber = 7;
percentage = 0.15; % Percentage of coin the middle part should be.
for k = 1 : length(props)
  % Crop the image
  croppedImage = imcrop(rgbImage, props(k).BoundingBox);
  % Display the images.
  subplot(3, 6, plotNumber);
  imshow(croppedImage, []);
  axis on;
  title('Cropped RGB Image', 'FontSize', fontSize, 'Interpreter', 'None');
  drawnow;
  
  % Now crop out the middle 50%
  % Get the dimensions of the image.
  [rows, columns, numberOfColorChannels] = size(croppedImage);
  row1 = round(rows * (0.5 - percentage));
  row2 = round(rows * (0.5 + percentage));
  col1 = round(rows * (0.5 - percentage));
  col2 = round(rows * (0.5 + percentage));
  middlePart = croppedImage(row1:row2, col1:col2, :);
  % Display the images.
  subplot(3, 6, plotNumber + 1);
  imshow(middlePart, []);
  axis on;
  title('Cropped RGB Image', 'FontSize', fontSize, 'Interpreter', 'None');
  drawnow;
  plotNumber = plotNumber + 2;
end

[ayesha abbassi]

Thank you sir . I also did the same thing It works. but your method is more easy.