语义分割中的类别不平衡的权重计算

这是5幅图，加上背景共5类。

可以参考这篇文章https://blog.csdn.net/u012426298/article/details/81232386

对于一个多类别图片数据库，每个类别都会有一个class frequency, 该类别像素数目除以数据库总像素数目, 求出所有class frequency 的median 值，除以该类别对应的frequency 得到weight：

weight=median(weights)/weights

#coding:utf-8
from __future__ import print_function
import os
import numpy as np
import cv2
w,h=512,512
def find_pic(img,array_list,n_class,pixs):img_sum = np.sum(img == array_list, axis=-1)pix_numbers=img_sum.reshape(-1).tolist().count(3)if pix_numbers:pixs+=pix_numbersn_class+=1return pixs,n_class
def compute_class(pixs,n_class):return pixs/(n_class*w*h)
def frequence():# images_path = './trainannot_visual'images_path = './visual_example'red = np.array([0, 0, 128])yellow = np.array([0, 128, 128])green = np.array([0, 128, 0])blue = np.array([128, 0, 0])back_gro = np.array([0, 0, 0])images_list_path = [os.path.join(images_path,i) for i in os.listdir(images_path)]n_red=0red_pixs=0n_yellow = 0yellow_pixs = 0n_green= 0green_pixs = 0n_blue = 0blue_pixs = 0n_back = 0back_pixs = 0for count,image_path in enumerate(images_list_path):print('{}image'.format(count))img=cv2.imread(image_path)red_pixs, n_red=find_pic(img,red,n_red,red_pixs)yellow_pixs,n_yellow = find_pic(img, yellow,n_yellow,yellow_pixs)green_pixs,n_green = find_pic(img, green,n_green,green_pixs)blue_pixs,n_blue = find_pic(img, blue,n_blue,blue_pixs)#back_pixs,n_back = find_pic(img, back_gro,n_back,back_pixs)print(red_pixs, n_red)print(yellow_pixs,n_yellow)print(green_pixs, n_green)print(blue_pixs, n_blue)print(back_pixs, n_back)f_class_red=compute_class(red_pixs,n_red)f_class_yellow = compute_class(yellow_pixs, n_yellow)f_class_green = compute_class(green_pixs, n_green)f_class_blue = compute_class(blue_pixs, n_blue)f_class_back = compute_class(back_pixs, n_back)print(f_class_red,f_class_yellow,f_class_green,f_class_blue,f_class_back)f_class=[f_class_red,f_class_yellow,f_class_green,f_class_blue,f_class_back]f_class_median=np.median(np.array(f_class))print(f_class_median)print(f_class_median/np.array(f_class))
if __name__ == '__main__':frequence()