Changing the size info of images per iteration in a for loop

Question

Lina Koronfel 2020-3-24

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/512574-changing-the-size-info-of-images-per-iteration-in-a-for-loop

评论： Ameer Hamza 2020-3-30

The situation: I'm running a for loop which anaylzes images. Each folder contains separate dataset and all are analyzed using a code that runs on subfolders within a parent folder. In some sub-folders, the Height and Width (H x W) of the images to be analyzed are different.

The problem: I get error whenever the code runs an iteration on a subfolder that contains images of different dimensions (H x W) compared to the sub-folder analyzed in the first iteration (k=1=True). What is missing here such that the code can be executed on images of different dimensions, smoothly?

Here is the relevent lines of the code I have, please read the comments:

for k = 1 : numberOfFolders;
if numberOfImageFiles >= 1600
   %....some code 
for s=InitFrameLast10:StartInt:LastFrameLast10; 
    for t=s:s+ImpFrames; 
         
    fullFileNameLast10=fullfile(thisFolder, baseFileNames{t});
    fprintf('      Now reading %s\n', fullFileNameLast10);
    imageArray_uncropLast10=imread(fullFileNameLast10);
     FigInfo=imfinfo(fullFileNameLast10);
    W=FigInfo.Width;
    H=FigInfo.Height;
   
%I want to assigning W and H (which changes per iteration) to PupilBigLast10
    
    PupilBigLast10(:,:,t)=imageArray_uncropLast10; 
%The line above is where I get the error that Right (not changing--want it to be flexible) and left (changes per folder iteration) are not equal
    
    %....some more code
    end 
end
%....more and more code

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Rik 2020-3-24

You are currently storing the entire content of imageArray_uncropLast10, not just its height and width. You can of course change the size of PupilBigLast10 to make imageArray_uncropLast10 fit inside it. Which of these two would you want to happen?

Lina Koronfel 2020-3-25

Yes exactly!! How can I change the size of PupilBigLast10 to make the changing dimensions of imageArray_uncropLast10 (which changes per iterartion of "k", or "numberOfFolders") fit inside it? Thank you

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Answer 1

Ameer Hamza 2020-3-25

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/512574-changing-the-size-info-of-images-per-iteration-in-a-for-loop#answer_421879

编辑：Ameer Hamza 2020-3-25

在 MATLAB Online 中打开

In MATLAB, it is not possible to create a 3D matrix with a different number of rows and columns in each slice. For such situations, we use cell arrays. You can do something like this:

Add this line at the place where you are initializing PupilBigLast10

PupilBigLast10 = {};

Then, replace the line

PupilBigLast10(:,:,t) = imageArray_uncropLast10;

with

PupilBigLast10{t} = imageArray_uncropLast10;

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Lina Koronfel 2020-3-26

在 MATLAB Online 中打开

Thank you for the prompt response. There are a couple of problems though. The iterations all yield similar results, which is not what I'm expecting. I placed the command you recommended under the "t" for-loop since this is when the H and W can be identified using imfinfo.

for s=InitFrameLast10:StartInt:LastFrameLast10; 
    for t=s:s+ImpFrames; %Selected frames/trial to be analyzed
         
    fullFileNameLast10=fullfile(thisFolder, baseFileNames{t});
    fprintf('      Now reading %s\n', fullFileNameLast10);
    
    imageArray_uncropLast10=imread(fullFileNameLast10);
   FigInfo=imfinfo(fullFileNameLast10);
   W=FigInfo.Width;
   H=FigInfo.Height;
   
    PupilBigLast10=zeros(H,W,t);
       
    PupilBigLast10(:,:,t)=imageArray_uncropLast10;
    BinaryPupilLast10(:,:,t)=im2bw(PupilBigLast10(:,:,t), 0.4);
    PixelCountLast10(t) = sum(sum(BinaryPupilLast10(:,:,t)));
           
    end 
end

and I also get the same error as before, but now on the following line ( P.S. if I also make BinaryPupilLast10=zeros (H,W,t)) I run out of memory

Unable to perform assignment because the size of the left side is 90-by-160 and the size of the right side is 94-by-160.
Error in BinaryPupilLast10(:,:,t)=im2bw(PupilBigLast10(:,:,t), 0.4);

Lina Koronfel 2020-3-26

在 MATLAB Online 中打开

Sorry I didn't copy the full section for the for loop. Here it is

for k = 1 : numberOfFolders;
    close all
    try
	% Get this folder and print it out.
	thisFolder = listOfFolderNames{k};
	fprintf('Processing folder %s\n', thisFolder); 
    
    filePattern = sprintf('%s/*.tif', thisFolder);
	baseFileNames = dir(filePattern);
    baseFileNames= natsortfiles({baseFileNames.name});
    numberOfImageFiles = length(baseFileNames);
if numberOfImageFiles >= 1601
    %some constants
    
for s=InitFrameLast10:StartInt:LastFrameLast10; 
    for t=s:s+ImpFrames; %Selected frames/trial to be analyzed
         
    fullFileNameLast10=fullfile(thisFolder, baseFileNames{t});
    fprintf('      Now reading %s\n', fullFileNameLast10);
    imageArray_uncropLast10=imread(fullFileNameLast10);
       FigInfo=imfinfo(fullFileNameLast10);
       W=FigInfo.Width;
       H=FigInfo.Height;
   
    PupilBigLast10=zeros(H,W,t);
       
    PupilBigLast10(:,:,t)=imageArray_uncropLast10;
    BinaryPupilLast10(:,:,t)=im2bw(PupilBigLast10(:,:,t), 0.4);
    PixelCountLast10(t) = sum(sum(BinaryPupilLast10(:,:,t)));
           
    end 
end
%more code

Lina KORONFEL 2020-3-30

在 MATLAB Online 中打开

Thank you so much Ameer!! I tested the code on several folders and it worked everytime with no errors. However, I had to create a zeros matrix for both PupilBig as well as BinaryPupilLast10, and to change the type from double to uint8, which is the type of imageArray_uncropLast10.

Here is the final code as it worked

for k = 1 : numberOfFolders;
    close all
    try
	% Get this folder and print it out.
	thisFolder = listOfFolderNames{k};
	fprintf('Processing folder %s\n', thisFolder); 
    
    filePattern = sprintf('%s/*.tif', thisFolder);
	baseFileNames = dir(filePattern);
    baseFileNames= natsortfiles({baseFileNames.name});
    numberOfImageFiles = length(baseFileNames);
if numberOfImageFiles >= 1601
    %some constants
    fullFileNameOfFolderForDimensionPurpose=fullfile(thisFolder, baseFileNames{1600});
    %imageArrayofFolderForDimensionPurpose=imread(fullFileNameOfFolderForDimensionPurpose);
       FigInfo=imfinfo(fullFileNameOfFolderForDimensionPurpose);
       H=FigInfo.Height;
       W=FigInfo.Width;
       
       %PupilBigLast10=zeros(H,W,k);
       PupilBig=zeros(H,W,k, 'uint8');
       BinaryPupilLast10=zeros(H,W,k, 'uint8');
       
for s=InitFrameLast10:StartInt:LastFrameLast10; 
    for t=s:s+ImpFrames; %Selected frames/trial to be analyzed
         
    fullFileNameLast10=fullfile(thisFolder, baseFileNames{t});
    fprintf('      Now reading %s\n', fullFileNameLast10);
    imageArray_uncropLast10=imread(fullFileNameLast10);
    PupilBigLast10(:,:,t)=imageArray_uncropLast10;
    BinaryPupilLast10(:,:,t)=im2bw(PupilBigLast10(:,:,t), 0.4);
    PixelCountLast10(t) = sum(sum(BinaryPupilLast10(:,:,t)));
           
    end 
end
%more code