How to Crop/Extract a specific location from satellite images using matlab

 i'm new to MATLAB , i want to extract this part (marked) from the RGB image. please help me

Answer 1

[Image Analyst]

Try this:

% Demo to have the user freehand draw an irregular shape over an image, ant then extract a cropped version.

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('cameraman.tif')); % Determine where demo folder is (works with all versions).
baseFileName = 'peppers.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);

% Now crop the image.
x = xy(:, 1);
y = xy(:, 2);
leftColumn = min(x);
rightColumn = max(x);
topLine = min(y);
bottomLine = max(y);
width = rightColumn - leftColumn + 1;
height = bottomLine - topLine + 1;
croppedImage = imcrop(rgbImage, [leftColumn, topLine, width, height]);
% Display cropped image.
subplot(2, 2, 3);
imshow(croppedImage);
axis on;
title('Cropped image', 'FontSize', fontSize);

Answer 2

[Image Analyst]

Use imfreehand. See attached demo.

[meenu v]

Error occurred, plz hlp...

[meenu v]

Error using iptassert (line 19) Size of I doesn't match size information found in the first input argument.

Error in regionprops>ParseInputs (line 1224) iptassert(isequal(sizeImage,size(I)), ...

Error in regionprops (line 205) [I,requestedStats,officialStats] = ParseInputs(imageSize, argOffset, varargin{:});

Error in Untitled7 (line 66) measurements = regionprops(binaryImage, grayImage, ...

[meenu v]

plz suggest any way to correct this error.