Saving .png images in directory

Greetings Everyone!

I am encountering a problem while saving .png files in a loop. I have multiple .png images with 256x256 unit8 dimesnions. I am combining those images to form a single image by using below code. But after saving the file the file has ne information of its height and width in its properties. Due to which I am unable to process those images further. Can anybody help me out?

%Specify training and test folders
train_fold  = ['..',filesep,'Train_Set',filesep];  
test_fold   = ['..',filesep,'Test_Set',filesep];

%Read train and test set images folder information
train_ims = dir(train_fold);
test_ims = dir(test_fold);

for y=1:1:3
%read 2nd training image's all masks
im_selected = 1;
train_ims_masks = dir([train_fold,train_ims(y).name,filesep,'masks',filesep]);

%read 2nd training image's all masks in sequence 
       for i = 1:length(train_ims_masks) 
           im{i} = imread([train_fold,train_ims(y).name,filesep,'masks',filesep,train_ims_masks(i).name]);  
       end
% Making new image by combining multiple images
  compositeImage = im{1};
       for k=2:length(train_ims_masks)
             compositeImage = compositeImage + im{k};
       end
 % saving new image into directory
   save (['compositeImage' num2str(y), '.png']);
   dir(train_fold);
     
end
figure
image(compositeImage)
colormap(gray)

Answer 1

[Guillaume]

The counterpart to imread is imwrite, not save. save as you've used it saves all the workspace variable in a mat file (irrespective of the extension you use).

Replace your save by:

imwrite(compositeImage, sprintf('CompsiteImage%d.png', y));

Note that I'm using sprintf to build the filename instead of string concatenation as you'd done. In my opinion, it's more readable. If you're going to use string concatenation, at the very least be consistent in your use of separator. You used a space to separate 'compositeImage' and num2str(y) and a comma to separate num2str(y) and '.png'.

[Hassan Ashraf]

Thank you Guillaume :)