MATLAB: How to create a matrix of the surf features for about 100 images

feature detectionmatricesmatrixmatrix arrayneural networksurf

Basically, I'm creating a Neural Network.. I have all of my images and I have the code to detect the SURF Features. Now, I need help to place the images with detected features into a matrix please.
This is the SURF code with the image it display with SURF points. I need to do this for 300 images made into a matrix to start training my NN.
clear;
close all;
I = imread('D:\test\chair\0001.png');
figure; imshow(I);
I = rgb2gray(I);
figure; imshow(I);
points = detectSURFFeatures(I);
figure;
imshow(I); hold on;
plot(points.selectStrongest(10));
[features, valid_points] = extractFeatures(I, points);
plot(valid_points.selectStrongest(5),'showOrientation',true);
coffee cup.png

Best Answer

Hello,
I am assuming that you are making use of a Neural Network for classification purpose.
Following code makes a row-wise matrix for 300 images using SURF features as descriptors. 
clear; 
close all 
clc; 
for i=1:300 
 st=strcat('D:\test\chair\000',num2str(i,'%02d'),'.png'); 
    I = imread(st); 
    I = rgb2gray(I); 
    points = detectSURFFeatures(I); 
    [features, valid_points] = extractFeatures(I, points); 
    [s1,s2]=size(features); 
    S=s1*s2; 
    ftr=reshape(features,1,S); 
    F(i,:)=ftr; 
end
The following link describes basic image classification using a simple convolution Neural Network:
I would like to suggest you make use of "Image category classification using a bag of features approach" which uses SURF features and SVM classifier. This gives you a single vector that you can use at the input to a neural network or any other classifier of your choice.
Please refer to the following link: https://www.mathworks.com/help/vision/examples/image-category-classification-using-bag-of-features.html
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