How to save information from a for loop

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Rohit Thokala
Rohit Thokala on 8 Jan 2022
Commented: yanqi liu on 10 Jan 2022
%% DEFINE input and output path
full_folder = 'C:\Users\RR\Desktop\practice\input_folder_T_60_inj_05';
output_folder = uigetdir("select folder");
input_files = fullfile(full_folder,"*.tif");
subfolders = dir(input_files);
%% background subtraction
background = im2uint16(mat2gray(imread(subfolders(1).name)));
%% Image processing
for i = 1 : length(subfolders)
image = im2uint16(mat2gray(imread(subfolders(i).name)));
image_back_sub = image - background;
image_gray = im2gray(image_back_sub);
tilt = imrotate(image_gray,-0.7,'bilinear','crop');
%color_inversion = imcomplement(image_gray); % this code works for color inversion
BinaryImage=imbinarize(tilt, 0.1);
bw1 = imopen(BinaryImage, strel('line', round(size(BinaryImage,2)*0.03), 0));
bw2 = imdilate(bw1, strel('square', 4));
bw3 = imdilate(bw2, strel('square', 2));
stats = regionprops(bw3);
data = struct2table(stats)
[~,idx] = max(data.Area(:,1))
r = data(idx,:)
sprayRadius = r.BoundingBox(1,3)
sprayHeight = r.BoundingBox(1,4)
imwrite(bw3,[output_folder '/', subfolders(i).name]);
end
stats is the table shown above. I want to store last two values as sprayRadius and sprayHeight in every iteration. How can I do this? Thanks in advance. Reference images are in the comments (img1,img2,background)
  3 Comments
Rohit Thokala
Rohit Thokala on 9 Jan 2022
Hello sir (@Image Analyst), I want only width and height of the spray associated with maximum area in the table, not all the heights and widths. I am attaching my full code here with three images (one background and two spray images) for code to run. This code is working to process single image and I want to loop this over a range of images and finally get width and height of all images. I am also attaching single image processing code.

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Accepted Answer

yanqi liu
yanqi liu on 10 Jan 2022
result = [];
%% Image processing
for i = 1 : length(subfolders)
image = im2uint16(mat2gray(imread(subfolders(i).name)));
image_back_sub = image - background;
image_gray = rgb2gray(image_back_sub);
tilt = imrotate(image_gray,-0.7,'bilinear','crop'); % impingement plate has little inclination
BinaryImage=imbinarize(tilt, 0.2);
bw1 = imopen(BinaryImage, strel('line', round(size(BinaryImage,2)*0.03), 0));
bw2 = imdilate(bw1, strel('square', 4));
bw3 = imdilate(bw2, strel('square', 2));
stats = regionprops(bw3);
data = struct2table(stats)
[~,idx] = max(data.Area(:,1))
r = data(idx,:)
figure; imshow(image, []); hold on;
for j = 1 : length(stats)
rectangle('Position', stats(j).BoundingBox, 'EdgeColor', 'r', 'LineWidth', 2);
end
% loop this over a range of images and finally get width and height of all images
sprayRadius = r.BoundingBox(1,3);
sprayHeight = r.BoundingBox(1,4);
% sn(i).filename = subfolders(i).name;
% sn(i).sprayRadius = sprayRadius;
% sn(i).sprayHeight = sprayHeight;
result{i,1} = subfolders(i).name;
result{i,2} = sprayRadius;
result{i,3} = sprayHeight;
imwrite(BinaryImage,[output_folder '/', subfolders(i).name]);
end
xlswrite('result.xlsx',result)
  7 Comments
yanqi liu
yanqi liu on 10 Jan 2022
clear all;
clc;
close all
%% DEFINE input and output path
full_folder = './input_folder_T_80_inj_10/';
output_folder = './out';
input_files = fullfile(full_folder,"*.jpg");
subfolders = dir(input_files);
result = [];
%% background subtraction
background = im2uint16(mat2gray(imread(fullfile(subfolders(1).folder,subfolders(1).name))));
%% Image processing
for i = 1 : length(subfolders)
image = im2uint16(mat2gray(imread(fullfile(subfolders(1).folder,subfolders(i).name))));
image_back_sub = image - background;
image_gray = rgb2gray(image_back_sub);
tilt = imrotate(image_gray,-0.7,'bilinear','crop');
%color_inversion = imcomplement(image_gray); % this code works for color inversion
BinaryImage=imbinarize(tilt, 0.1);
B2 = bwareafilt(BinaryImage, 1); % select the largest component with bwareafilt
% imshowpair(B,B2,"montage")
bw1 = imopen(B2, strel('line', round(size(BinaryImage,2)*0.07), 0));
bw2 = imdilate(bw1, strel('square', 2));
widthIndex = any(B2);
horizontalPixelWidth = find(widthIndex,1,'last')-find(widthIndex,1,'first');
verticalPixelHeight = find(any(B2,2),1,'last') - find(any(bw2,2),1,'first');
imwrite(bw2,[output_folder '/', subfolders(i).name]);
result{i,1} = subfolders(i).name;
result{i,2} = horizontalPixelWidth;
result{i,3} = verticalPixelHeight;
end
result
xlswrite('result.xlsx',result)

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More Answers (1)

Image Analyst
Image Analyst on 9 Jan 2022
What is b? It shows b in the error but I don't see it in your code. You might have to attach your entire m-file.
Maybe try
bb = vertcat(stats.BoundingBox);
allWidths = bb(:, 3);
allHeights = bb(:, 4);
sprayRadius(i) = max(allWidths);
sprayHeights(i) = max(allHeights);

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