yolov3 anchor 理解

yolov3 中的anchor 的框框是在训练集中聚类所得，在yolov3 中每个格子有9个anchor

mask52= [0,1,2]
  mask26= [3,4,5]
  mask13= [6,7,8]
    

  anchors=[ 10,13, 16,30, 33,23,
        30,61, 62,45, 59,119,
        116,90, 156,198, 373,326]

• yolov3 有9个anchor 点

#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""
Created on Mon Apr 19 20:54:27 2021

@author: ledi
"""

#!/usr/bin/env python
# -*- coding:utf-8 -*-
import cv2
def showPrioriBox():
    #输入图片尺寸
    INPUT_SIZE = 416

    mask52= [0,1,2]
    mask26= [3,4,5]
    mask13= [6,7,8]
    
    #0--->(10,13) 
    #1--->(16,30) .....
    anchors=[ 10,13, 16,30, 33,23,
              30,61, 62,45, 59,119,
              116,90, 156,198, 373,326]
    FEATURE_MAP_SIZE=26
    SHOW_ALL_FLAG  = True  # 显示所有的方框
    GRID_SHOW_FLAG =True

    # cap = cv2.VideoCapture("street.jpg")
    picPath = './car.jpg'
    picName = picPath.split('/')[-1]
    img = cv2.imread(picPath)
    print("original img.shape: ",img.shape)  # (1330, 1330, 3)
    img = cv2.resize(img,(INPUT_SIZE, INPUT_SIZE))

    # 显示网格
    if GRID_SHOW_FLAG:
        height, width, channels = img.shape
        GRID_SIZEX =  int(INPUT_SIZE/FEATURE_MAP_SIZE)
        for x in range(0, width - 1, GRID_SIZEX):
            cv2.line(img, (x, 0), (x, height), (150, 150, 255), 1, 1)  # x grid
        
        GRID_SIZEY = int(INPUT_SIZE / FEATURE_MAP_SIZE)
        for y in range(0, height - 1, GRID_SIZEY):
            cv2.line(img, (0, y), (width, y), (150, 150, 255), 1, 1)  # x grid
        # END：显示网格
#       cv2.imshow('Hehe', img)
#       cv2.imwrite('./' + picName.split('.')[0] + '_grid.' + picName.split('.')[1], img)

    if SHOW_ALL_FLAG or FEATURE_MAP_SIZE==13:
        for ele in mask13:
            # print(ele)
            
            
            # import cv2    图片   起点     终点      颜色      厚度
            # cv2.rectangle(img, (x1, y1), (x2, y2), (255,0,0),  2   )
            
            # x1,y1 ------
            # |          |
            # |          |
            # |          |
            # --------x2,y2

            
            cv2.rectangle(img, (int(INPUT_SIZE * 0.5 - 0.5*anchors[ ele * 2]), int(INPUT_SIZE * 0.5 -  0.5*anchors[ ele * 2 + 1])   ),
                               (int(INPUT_SIZE * 0.5 + 0.5*anchors[ ele * 2]),int(INPUT_SIZE * 0.5 + 0.5*anchors[ ele * 2 + 1])), 
                                   (0, 255-ele*10, 0), 2)
        # cv2.imwrite('./' + picName.split('.')[0] + '_saveMask13.' + picName.split('.')[1], img)
            # cv2.imshow('img', img)
    if SHOW_ALL_FLAG or FEATURE_MAP_SIZE==26:
        for ele in mask26:
            # print(ele)
            cv2.rectangle(img, (int(INPUT_SIZE * 0.5 - 0.5*anchors[ ele * 2]), int(INPUT_SIZE * 0.5 -  0.5*anchors[ ele * 2 + 1])   ),
                          (int(INPUT_SIZE * 0.5 + 0.5*anchors[ ele * 2]),int(INPUT_SIZE * 0.5 + 0.5*anchors[ ele * 2 + 1])          ), 
                          (255, 255-ele*10, 0), 2)
        # cv2.imwrite('./' + picName.split('.')[0] + '_saveMask26.' + picName.split('.')[1], img)

    if SHOW_ALL_FLAG or FEATURE_MAP_SIZE==52:
        for ele in mask52:
            # print(ele)
            cv2.rectangle(img, (int(INPUT_SIZE * 0.5 - 0.5*anchors[ ele * 2]), int(INPUT_SIZE * 0.5 -  0.5*anchors[ ele * 2 + 1])    ),
                          (int(INPUT_SIZE * 0.5 + 0.5*anchors[ ele * 2]),int(INPUT_SIZE * 0.5 + 0.5*anchors[ ele * 2 + 1]))
                          , (0, 255-ele*10, 255), 1)
        # cv2.imwrite('./' + picName.split('.')[0] + '_saveMask52.' + picName.split('.')[1], img)


    cv2.imwrite('./' + picName.split('.')[0] + '_allSave.' + picName.split('.')[1], img)

    cv2.imshow('img', img)
    while cv2.waitKey(1000) != 27:  # loop if not get ESC.
        if cv2.getWindowProperty('img', cv2.WND_PROP_VISIBLE) <= 0:
            break
    cv2.destroyAllWindows()

if __name__ == '__main__':
    showPrioriBox()