概述

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graph 
	A(取3*3的像素点) -->B(视为2*2相邻格子)
    B --> C(获得2*2区分度S)
    C -->|存在阈值D > S| D(标记为0)
    C -->|存在阈值D < S| E(标记为1)
    D --> F(对01位置进行分类)
    E --> F
    F -->|3:1| G(标为蓝色)
    F -->|2:2相邻| H(标为绿色)
    F -->|2:2对角| I(标为红色)

效果示例

D = 20

image-20220524113247987

D = 30

image-20220524113357450

D = 40

image-20220524113553600

代码示例

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# python3.8
# utf-8

import cv2 as cv
import numpy as np


def get_qufendu(array):
    qufendu = np.zeros((2, 2))
    result = np.zeros((2, 2))
    for i in range(2):
        for j in range(2):
            qufendu[i][j] = max(array[i][j], array[i+1][j], array[i+1][j+1], array[i][j+1]) - min(array[i][j], array[i+1][j], array[i+1][j+1], array[i][j+1])
            if qufendu[i][j] > 40:
                result[i][j] = 1
    return result


def classify_array(array):
    a_sum = array[0][0] + array[0][1] + array[1][1] + array[1][0]
    if a_sum == 0 or a_sum == 4:
        return 0
    elif a_sum == 1 or a_sum == 3:
        return 1
    elif a_sum == 2:
        if array[0][0] == array[0][1]:
            return 2
        else:
            return 3


def get_channel_flag(channel, channel_flag, k):
    row, col, cnt_channel = channel.shape
    for i in range(row-2):
        for j in range(col-2):
            array33 = np.zeros((3, 3))
            for x in range(3):
                for y in range(3):
                    array33[x][y] = channel[i+x][j+y][k]
            array_flag = get_qufendu(array33)
            channel_flag[i+1][j+1][k] = classify_array(array_flag)
    return channel, channel_flag


def get_flag(img):
    flag = np.zeros(img.shape)
    row, col, cnt_channel = img.shape
    for k in range(cnt_channel):
        img, flag = get_channel_flag(img, flag, k)
    return flag


def get_value(pixel, flag):
    if flag == 1:
        pixel[0] = 255
        pixel[1] = 0
        pixel[2] = 0
    elif flag == 2:
        pixel[0] = 0
        pixel[1] = 255
        pixel[2] = 0
    elif flag == 3:
        pixel[0] = 0
        pixel[1] = 0
        pixel[2] = 255
    else:
        pixel[0] = 255
        pixel[1] = 255
        pixel[2] = 255
    return pixel


def mark(img, flag):
    row, col, cnt_channel = img.shape
    for i in range(row):
        for j in range(col):
            if flag[i][j][0] == flag[i][j][1] and flag[i][j][1] == flag[i][j][2]:
                img[i][j] = get_value(img[i][j], flag[i][j][0])
    return img


def main(img):
    p = cv.imread(img, 1)
    b, g, r = cv.split(p)
    flag = get_flag(p)
    p = mark(p, flag)
    cv.imwrite('mark_' + img, p)


if __name__ == '__main__':
    img_addr = '8068.jpg'
    main(img_addr)