Double loop over images

Hi guys! So i have this question: is there a way to double loop a lot of images?

What i mean is that i know how to loop over a lot of images (of the same type for example .png) lets say i have the next 10 images with names: c1=10.2 , c2=10.2 up to c10=10.2 with the next lines of code i can read them all and do what i want next with them

for n=1:10
  images{n} = imread(sprintf('c%d=10.2.png',n));
  %code ....
end  

but if i lets say want to loop over this for loop and have lets say a code that for the numbers 10 30 50 70 and 100 reads firstly the images with names c1=10.2 up to c10=10.2 and then does the previous for loop and when that for loop is done does the same thing for the c1=30.2 up to c10=30.2 and then for 50 and then 70 and then finally for 100 c1=100.2 up to c10=100.2 .

so it will read

c1=10.2 .... c10=10.2 and then read all the images c1=30.2 up to c10=30.2 and then c1=50.2 up to c10=50.2 and then c1=70.2 ... c10=70.2 and finally c1=100.2 .... c10=100.2

I hope i expained it well !

[Rik]

The sprintf function accepts multiple inputs so you can simply nest the two loops.

[george korris]

thank you for your answer Rik! do you mean like

for m=10:100
for n=1:10
  images{n,m} = imread(sprintf('c%d=%d0.2.png',n,m));
  %code ....
end  
end

im not sure how to write the new sprintf ,if you can show me it would be great

[george korris]

ok so i think this code works

for m=10:20:70
for n=1:10
  images{n,m} = imread(sprintf('c%d=%d.2.png',n,m));
  %code ....
end  
end

but is it reading the images in the corect way ??

c1=10.2 .... c10=10.2 and then read all the images c1=30.2 up to c10=30.2 and then c1=50.2 up to c10=50.2 and then c1=70.2 ... c10=70.2 and finally c1=100.2 .... c10=100.2

[Jan]

Just try it:

for m=10:20:70
  for n=1:10
    sprintf('c%d=%d.2.png',n,m)
  end  
end

[george korris]

yeah you are write Jan thank you guys you are awesome!!! So there is no way for it to read the pics up to 100 since they are not +20 from 70 ?? i can only read 10 30 50 and 70 write? not 100 also?

Answer 1

[Image Analyst]

Try this:

folder = pwd;
% Now we have a list of all the filenames.
% Now how another loop that reads in one image with names like 10, 30, 50, ...
% and an inner loop that does 1-10.
outLoopValues = [10, 30, 50, 70, 100] % Whatever values you want.
for k = 1 : length(outLoopValues)
	index = outLoopValues(k);
	for n = 1 : 10
		thisBaseFileName = sprintf('c%d=%d.2.png', n, index);
		thisFileName = fullfile(folder, thisBaseFileName);
		if isfile(thisFileName)
			fprintf('Processing "%s"\n', thisFileName);
			% Code to call imread and process this image ...
		else
			% File doesn't exist.
			fprintf('    !!!! Skipping non-existent file: "%s"\n', thisFileName);
			continue;
		end
	end
	fprintf('\n'); % Print blank line between groups.
end
fprintf('Done running %s.m\n', mfilename);

[Image Analyst]

You may not be able to read in and store all the images in a cell array, so just read it in and don't store it in another array. Just call imread() in the inner loop and process the image right then and there.

[george korris]

Thank you very much Image Analyst!

[george korris]

sorry to bother you again but how can i add the images that i read inside the double loop?

i tried

K = imadd(img_rot{n,index},'uint16');

but it didn't work