MATLAB: How to store and plot values in a loop

image analysisimage processingImage Processing ToolboxMATLAB

The code below currently reads in all the jpg images in a file and outputs the average intensity of the imagearray (sum of image matrix), what I am struggling to do, is convert this code so that it measures the intensity of each singular image, stores the value and then plots the change in intensity across all the images.
ImageFolder = 'H:\My Documents\Dissertation';
if ~isfolder(ImageFolder)
ErrorMessage = print('Error: The following folder does not exist: Please specify a new folder.', ImageFolder);
uiwait(warndlg(ErrorMessage));
ImageFolder = uigetdir();
if ImageFolder == 0
return;
end
end
FileType = fullfile(ImageFolder, '*.jpg');
TheImages = dir(FileType);
for k = 1:length(TheImages)
baseFileName = TheImages(k).name;
fullFileName = fullfile(TheImages(k).folder, baseFileName);
if exist(fullFileName,'file')
imageArray = imread(fullFileName);
end
meanIntensity = mean(imageArray(:));
matrix(k) = mean(imageArray(:));
end
plot(k,meanIntensity,'-.x');
hold on

Best Answer

Try it like this:
ImageFolder = 'H:\My Documents\Dissertation';
if ~isfolder(ImageFolder)
	ErrorMessage = print('Error: The following folder does not exist: Please specify a new folder.', ImageFolder);
	uiwait(warndlg(ErrorMessage));
	ImageFolder = uigetdir();
	if ImageFolder == 0
		return;
	end
end
filePattern = fullfile(ImageFolder, '*.jpg');
TheImages = dir(filePattern);
for k = 1 : 10% length(TheImages)
	baseFileName = TheImages(k).name;
	fullFileName = fullfile(TheImages(k).folder, baseFileName);
% 	if ~isfile(fullFileName,'file') % Will never happen because you used dir()
% 		continue;
% 	end
	imageArray = imread(fullFileName);
	meanIntensity(k) = mean(imageArray(:));
end
plot(meanIntensity,'-.x', 'LineWidth', 2, 'MarkerSize', 16);
hold on
grid on;
title('Image Means', 'FontSize', 18);
xlabel('Index', 'FontSize', 18);
ylabel('Mean Gray Level', 'FontSize', 18);
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