Apply a sliding window to an image to extract hog features (python)

hog_sliding_window.py

from skimage.feature import hog
import numpy as np

image_height = 48
image_width = 48
window_size = 24
window_step = 6

def sliding_hog_windows(image):
    hog_vector = []
    for y in xrange(0, image_height, window_step):
        for x in xrange(0, image_width, window_step):
            window = image[y:y+window_size, x:x+window_size]
            hog_vector.extend(hog(window, orientations=8, pixels_per_cell=(8, 8),
                                            cells_per_block=(1, 1), visualise=False))
    return hog_vector
    
image = np.load('image.npy')
hog_vector = sliding_hog_windows(image)