change size of images

I have a database of thousands of images of different sizes like 45x78, 67x89, 83x99 etc. how to make all the images of same size?

Answer 1

[KSSV]

Read about imresize. Run a loop for each image and change them and save them if you want using imwrite.

[Jyoti Nautiyal]

how to run loop when images have random names?

Answer 2

[Image Analyst]

@Jyoti Nautiyal, try this full demo. If it works, could you Vote for the Answer:

% Demo by Image Analyst.
clc;    % Clear the command window.
fprintf('Beginning to run %s.m ...\n', mfilename);
close all;  % Close all figures (except those of imtool.)
clearvars;
workspace;  % Make sure the workspace panel is showing.
format long g;
format compact;
fontSize = 16;

% FAQ reference:
% https://matlab.fandom.com/wiki/FAQ#How_can_I_process_a_sequence_of_files.3F

% Specify the folder where the files live.
inputFolder = pwd; % or 'C:\Users\yourUserName\Documents\My Pictures';
% Check to make sure that folder actually exists.  Warn user if it doesn't.
if ~isfolder(inputFolder)
	errorMessage = sprintf('Error: The following folder does not exist:\n%s\nPlease specify a new folder.', inputFolder);
	uiwait(warndlg(errorMessage));
	inputFolder = uigetdir(); % Ask for a new one.
	if inputFolder == 0
		% User clicked Cancel
		return;
	end
end
outputFolder = fullfile(inputFolder, 'Resized');
if ~isfolder(outputFolder)
	mkdir(outputFolder);
end

% Specify how many rows and columns you want the output image to be.
desiredRows = 60;
desiredColumns = 90;

% Get a list of all files in the folder with the desired file name pattern.
filePattern = fullfile(inputFolder, '*.png'); % Change to whatever pattern you need.
theFiles = dir(filePattern);
for k = 1 : length(theFiles)
	baseFileName = theFiles(k).name;
	fullFileName = fullfile(theFiles(k).folder, baseFileName);
	fprintf(1, 'Now reading %s\n', fullFileName);
	% Now do whatever you want with this file name,
	% such as reading it in as an image array with imread()
	imageArray = imread(fullFileName);
	subplot(2, 1, 1);
	imshow(imageArray);  % Display image.
	axis('on', 'image');
	caption = sprintf('Original "%s"', baseFileName);
	title(caption, 'Interpreter', 'none');
	% Resize the image
	resizedImageArray = imresize(imageArray, [desiredRows, desiredColumns]);
	subplot(2, 1, 2);
	imshow(resizedImageArray);  % Display image.
	axis('on', 'image');
	caption = sprintf('Resized "%s"', baseFileName);
	title(caption, 'Interpreter', 'none');
	drawnow; % Force display to update immediately.
	% Write it to the output folder
	outputFullFileName = fullfile(outputFolder, baseFileName);
	imwrite(resizedImageArray, outputFullFileName);
end
fprintf('Done running %s.m\n', mfilename);