Matlab Query: Image Processing, Editing the Script

Question

I am quite new to image processing and would like to produce an array that stores 10 images. After which I would like to run a for loop through some code that identifies some properties of the images, specifically the surface area of a biological specimen, which then spits out an array containing 10 areas.

Below is what I have managed to scrap up so far, and this is the ensuing error message:

??? Index exceeds matrix dimensions.

Error in ==> Testing1 at 14
    nova(i).img = imread([myDir B(i).name]);

Below is the code I've been working on so far:

my_Dir = 'AC04/';
ext_img='*.jpg';

B = dir([my_Dir ext_img]);
nfile = max(size(B));

nova = zeros(1,nfile);

for i = 1:nfile
    nova(i).img = imread([myDir B(i).name]);
end

areaarray = zeros(1,nfile);

for k = 1:nfile

[nova(k), threshold] = edge(nova(k), 'sobel');
.
.
.
.%code in this area is irrelevant to the problem I think%
.
.
.
areaarray(k) = bwarea(BWfinal);

end

areaarray

Answer 1

There are few ways you could store an image in a kind of an array structure in Matlab. You could use array of struct s. In that case you could do as you did:

nova(i).img = imread([myDir B(i).name]);

You access first image with nova(1).img , second one with nova(2).img etc.

---

Other way to do it is to use cell array (similar to arrays but are more flexible in the sense that members could be of the different type):

nova{i} = imread([myDir B(i).name]);

You access first image with nova{1} , second one with nova{2} etc.

---

[ IMPORTANT ] In both cases you should remove this line from code:

nova = zeros(1,nfile);

I suppose you've tried to pre-allocate memory for images, and since you're beginner I advise you not to be concerned with it. It is an optimization concern to be addressed if you come across some performance issues - and if you don't come across them, take advantage of Matlab's automatic memory (re)allocation.