I have folder with name 'images' within that folder 20 sub-folders are there. that sub-folder consist 20 images with name like 'img (1).gif'. I have to read images one by one then store the hog features in the text file.

objects={'apple','bat','beetle'};%apple,bat,beetle are sub-folder name
trimgs=10;
for i=1:length(objects)
    for j=1:trimgs
        imgpath=['.\images\' objects{i} '\img (' int2str(j) ').gif']; 

          I=imread(imgpath);
          J = imresize(I,[256,256]);
          fid=fopen('feature_vector.txt','w');
          fprintf(fid,'%i\t',hog_feature_vector(J));
          fprintf(fid,'\n');
          fclose(fid);

      end
  end

Answer 1

[Cam Salzberger]

What issues are you running into? Or what is your question?

I can suggest that you consider using "dir" to automatically get the "objects" name.

If you are using the same "feature_vector.txt" file for all the images, you probably want to use fopen with the 'a' option (for "append") rather than the 'w' option (for "write", discarding current contents).

[bamini thavarajah]

I'm using the same "feature_vector.txt" file for all the images. when I use fopen with 'a' that work correctly. But I want to print all image features in the matrix form. How can I modify my code?

[Cam Salzberger]

I don't know what "hog_feature_vector". However, if it is a vector of integers, then your line:

fprintf(fid,'%i\t',hog_feature_vector(J));

seems like it would work correctly. What are you seeing when you run this? I would expect it to output something similar:

x = [1 2 3 4 5];
fprintf('%i\t',x)
1  2  3  4  5

If by "matrix output" you mean you want square brackets and stuff, you can just add that before you print each line.

Answer 2

[Image Analyst]

See the FAQ: http://matlab.wikia.com/wiki/FAQ#How_can_I_process_a_sequence_of_files.3F

[bamini thavarajah]

thank you.. I have to print hog features in matrix form to all images. how can I write matlab coding for this? I have used this hog function https://in.mathworks.com/matlabcentral/answers/354491-i-have-folder-with-name-images-within-that-folder-20-sub-folders-are-there-that-sub-folder-consis#comment_480718

[Image Analyst]

The link you gave just points back here. Basically learn how to use fprintf() and you can write out anything you want to a text file.