clc; clear;

img1 = imread('cat.jpg'); img2 = imread('homealone.jpg'); img1_gray = rgb2gray(img1); img2_gray = rgb2gray(img2);

x = 3; y = 4;

[g_pyr1, dog_pyr1] = generate_gaussian_pyramid(img1_gray, x, y); [g_pyr2, dog_pyr2] = generate_gaussian_pyramid(img2_gray, x, y);

keypoints1 = find_keypoints(dog_pyr1); keypoints2 = find_keypoints(dog_pyr2);

keypoints1 = assign_orientation(g_pyr1, keypoints1); keypoints2 = assign_orientation(g_pyr2, keypoints2);

descriptors1 = compute_descriptors(g_pyr1, keypoints1); descriptors2 = compute_descriptors(g_pyr2, keypoints2);

matches = match_features(descriptors1, descriptors2, 0.7);

figure; imshow(img1_gray); hold on; plot(keypoints1(:, 1), keypoints1(:, 2), 'ro', 'MarkerSize', 10);

figure; imshow(img2_gray); hold on; plot(keypoints2(:, 1), keypoints2(:, 2), 'ro', 'MarkerSize', 10);

figure; show_matches(img1_gray, img2_gray, keypoints1, keypoints2, matches);

i have this error in this code

Unrecognized function or variable 'generate_gaussian_pyramid'.

Error in odev1 (line 13) [g_pyr1, dog_pyr1] = generate_gaussian_pyramid(img1_gray, x, y);

and this the question :

Without using any library, apply the Sift algorithm to two similar images and show the matching keypoints. matlab code