Hi all I am working on enhancing a grayscal images, the first step should be cropping the image by removing lead and trail zeros (zeros rows an columns surrounding the image). i want t remove the surrounding zeros. please be advised that the cropping has be applied on zeros rows and columns that surrounding the image for different images, so i need a function or an algorithm does this cropping on different images. thanks in advance
MATLAB: Deleting leadind and trail zeros in an image
cropping black boundaryimage processingImage Processing Toolbox
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Try this:
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 short g;format compact;fontSize = 25;%===============================================================================
% Get the name of the image the user wants to use.
baseFileName = 'depth6.png';% Get the full filename, with path prepended.
folder = pwdfullFileName = 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; endend%===============================================================================% Read in demo image.
grayImage = imread(fullFileName);% Get the dimensions of the image.
% numberOfColorChannels should be = 1 for a gray scale image, and 3 for an RGB color image.
[rows, columns, numberOfColorChannels] = size(grayImage)if numberOfColorChannels > 1 % It's not really gray scale like we expected - it's color.
% Use weighted sum of ALL channels to create a gray scale image.
% grayImage = rgb2gray(grayImage);
% ALTERNATE METHOD: Convert it to gray scale by taking only the green channel,
% which in a typical snapshot will be the least noisy channel.
grayImage = grayImage(:, :, 2); % Take green channel.
end% Display the original image.
subplot(2, 2, 1);imshow(grayImage, []);axis on;caption = sprintf('Original Image, %s', baseFileName);title(caption, 'FontSize', fontSize, 'Interpreter', 'None');drawnow;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')% Find the white surround.
binaryImage = grayImage > 45000 & grayImage < 50000;% Fill the image to get rid of black spot at center.
binaryImage = imfill(binaryImage, 'holes');% Take the largest blob only.
binaryImage = bwareafilt(binaryImage, 1);% Display the image.
subplot(2, 2, 2);histogram(grayImage);title('Histogram of depth image', 'FontSize', fontSize);grid on;subplot(2, 2, 3);imshow(binaryImage, []);axis on;caption = sprintf('Binary Image');title(caption, 'FontSize', fontSize, 'Interpreter', 'None');hp = impixelinfo();drawnow;% Get the bounding box of the blob.
props = regionprops(binaryImage, 'BoundingBox');yTop = props.BoundingBox(2)xLeft = props.BoundingBox(1)width = props.BoundingBox(3);height = props.BoundingBox(4);% Erase bottom half, assuming shoulders won't be down there.
yBottom = round(yTop + height/2);binaryImage(yBottom:end, :) = false;% Display the image.subplot(2, 2, 4);imshow(binaryImage, []);axis on;caption = sprintf('Binary Image');title(caption, 'FontSize', fontSize, 'Interpreter', 'None');% Get bounding box again on just the top half
props = regionprops(binaryImage, 'BoundingBox');boundingBox = props.BoundingBoxyTop = boundingBox(2)xLeft = boundingBox(1)shoulderWidth = boundingBox(3)height = boundingBox(4)% Put up red rectangle around shoulders:
rectangle('Position', round(boundingBox), 'EdgeColor', 'r', 'LineWidth', 2);message = sprintf('The shoulder width = %d', shoulderWidth);title(message, 'FontSize', fontSize, 'Interpreter', 'None');uiwait(helpdlg(message));
Convert to grayscale and then threshold and find the bounding box
clc; % Clear the command window.
close all; % Close all figures (except those of imtool.)
imtool close all; % Close all imtool figures.
clear; % Erase all existing variables. Or clearvars if you want.
workspace; % Make sure the workspace panel is showing.
format long g;format compact;fontSize = 20;% Read in the color image.
folder = pwd;baseFileName = 'm2.bmp';% 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; endendrgbImage = imread(fullFileName);% Get the dimensions of the image. numberOfColorBands should be = 3.
[rows, columns, numberOfColorBands] = size(rgbImage);% Display the original color image.
subplot(2, 3, 1);imshow(rgbImage, []);axis on;title('Original Color Image', 'FontSize', fontSize);drawnow;% Enlarge figure to full screen.
set(gcf, 'units','normalized','outerposition',[0 0 1 1]);% Histogram the red channel, but there is a huge spike at 255 so let's not count those.
subplot(2, 3, 2);grayImage = rgb2gray(rgbImage);imshow(grayImage, []);title('Gray Scale version', 'FontSize', fontSize);subplot(2, 3, 3);histogram(grayImage(grayImage<255))grid on;title('Histogram of Gray Scale Image', 'FontSize', fontSize);someThresholdValue = 150;binaryImage = grayImage > someThresholdValue;% Take largest blob
binaryImage = bwareafilt(binaryImage, 1);subplot(2, 3, 4);imshow(binaryImage);grid on;title('Binary Image', 'FontSize', fontSize);% Label the binary image.
labeledImage = bwlabel(binaryImage);props = regionprops(labeledImage, 'BoundingBox');bbox = props.BoundingBoxcroppedImageRGB = imcrop(rgbImage, bbox);subplot(2, 3, 5);imshow(croppedImageRGB);grid on;title('Cropped RGB Image', 'FontSize', fontSize);% Gray scale version of cropped image
croppedImageGray = imcrop(grayImage, bbox);subplot(2, 3, 6);imshow(croppedImageGray);grid on;title('Cropped Gray Scale Image', 'FontSize', fontSize);
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