How can i extract desired image from an image?

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Usman 2015-11-22

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https://ww2.mathworks.cn/matlabcentral/answers/256845-how-can-i-extract-desired-image-from-an-image

评论： Image Analyst 2015-11-22

In the attached figure, I have to extract the visible part (i.e. rectangular eye part) in order to have focused eye region. I have tried imcrop function and it does what I need. But everytime i have to select the image co-ordinates. I want to do it automatically, like MATLAB itself sense the co-ordinates and extract that focused eye part. I mean there might be some algorithm which can vanish the black part and extract visible one. anybody have idea, how to do it?

cr1=imcrop(fmr_ext1,[500.5 388.5 85 117]);

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Answer 1

Image Analyst 2015-11-22

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https://ww2.mathworks.cn/matlabcentral/answers/256845-how-can-i-extract-desired-image-from-an-image#answer_200791

在 MATLAB Online 中打开

You can get the bounding box and then use crop:

measurements = regionprops(grayImage>0, 'BoundingBox');
croppedImage = imcrop(grayImage, measurements.BoundingBox);

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Image Analyst 2015-11-22

在 MATLAB Online 中打开

When I downloaded your image, I found out it was corrupted with a white border and bad JPG artifacts so I had to clean those up. DO NOT use JPG images for image processing. More robust code is below:

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 = 15;
%===============================================================================
% Read in a gray scale demo image.
folder = pwd;
% Get the full filename, with path prepended.
baseFileName = 'd.jpg';
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
grayImage = imread(fullFileName);
% Get the dimensions of the image.  
% numberOfColorBands should be = 1.
[rows, columns, numberOfColorChannels] = size(grayImage);
if numberOfColorChannels > 1
  % It's not really gray scale like we expected - it's color.
  % Convert it to gray scale by taking only the green channel.
  grayImage = grayImage(:, :, 2); % Take green channel.
end
% Display the image.
subplot(2, 2, 1);
imshow(grayImage, []);
title('Original Grayscale Image', 'FontSize', fontSize, 'Interpreter', 'None');
% 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') 
% Threshold (binarize) the image.
binaryImage = grayImage > 10;
% Get rid of white border/frame that is there for some weird reason.
binaryImage = imclearborder(binaryImage);
% Because he used a JPG image instead of PNG, 
% there are tons of jpg artifacts.
% Take the largest blob.
binaryImage = bwareafilt(binaryImage, 1);
subplot(2, 2, 2);
imshow(binaryImage, []);
title('Binary Image', 'FontSize', fontSize, 'Interpreter', 'None');
% Find the bounding box.
labeledImage = bwlabel(binaryImage);
measurements = regionprops(labeledImage, 'BoundingBox');
croppedImage = imcrop(grayImage, measurements.BoundingBox);
% Display the cropped image.
subplot(2, 2, 3);
imshow(croppedImage, []);
title('Cropped', 'FontSize', fontSize, 'Interpreter', 'None');

Usman 2015-11-22

thanks it works in 2015a..thankyou alot

Image Analyst 2015-11-22

ExtractBiggestBlob.m

See my own function, attached, written before they came out with bwareafilt().

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How can i extract desired image from an image?

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How can i extract desired image from an image?

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