实例中滑动窗口HOG特征向量是如何计算的，怎么得到计算结果的？

Question

-*- coding: utf-8 -*-

import cv2
import numpy as np
from skimage.feature import hog

initialization

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

image = cv2.imread('a.jpg', 0) #a.jpg是一个48*48的灰度图像

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

features = sliding_hog_windows(image) #程序调试得到的结果是：features是一个2592维向量，手动计算怎么计算？