前言

本篇博客使用Python+OpenCV判断图像是黑底还是白底，利用图像对角线上的黑白像素点个数进行判断，详情见下文。

本篇博客内容包含代码逻辑、说明、依赖、实现，这几部分。代码实现部分包含2种实现方式，1种进行二值化操作，1种不进行二值化操作。Python版本为3.6。

代码逻辑

导入OpenCV第三方库。
读入图像。
图像灰度化。
图像二值化。
获取图像2条对角线上黑白像素点个数。
比较黑白像素点个数，若黑像素多于白像素，则为黑底；否则为白底。

代码说明

代码包含2种实现方式，1种进行二值化操作，即BorW_binary()函数；1种不进行二值化操作，即BorW_not_binary()函数。
main函数中可以通过imread()更改输入图像、也可通过bwThresh变量更改判断黑白像素的阈值。

代码依赖

Python == 3.6
opencv-python == 4.5.5.62

代码实现

# This script is used to judge a image is black based or white based
import cv2# binarization
def BorW_binary(img, bwThresh):gray = cv2.cvtColor(img.copy(), cv2.COLOR_BGR2GRAY)  # gray imageret, thresh = cv2.threshold(gray, bwThresh, 255, cv2.THRESH_BINARY)  # binarization# get h and w of imgimgShape = img.shapeh = imgShape[0]w = imgShape[1]# init black and white point numberblackNum, whiteNum = 0, 0k = h / wfor x in range(w):y1 = int(k * x)y2 = int((-k) * x + h - 1)# prevent overflowif 0 <= y1 <= (h - 1) and 0 <= y2 <= (h - 1):# first diagonal lineif thresh[y1][x] == 0:blackNum += 1else:whiteNum += 1# second diagonal lineif thresh[y2][x] == 0:blackNum += 1else:whiteNum += 1print(blackNum, whiteNum)if blackNum > whiteNum:print("black based image")else:print("white based image")# not binary
def BorW_not_binary(img, bwThresh):gray = cv2.cvtColor(img.copy(), cv2.COLOR_BGR2GRAY)  # gray image# ret, thresh = cv2.threshold(gray, 127, 255, cv2.THRESH_BINARY)  # binarization# get h and w of imgimgShape = img.shapeh = imgShape[0]w = imgShape[1]# init black and white point numberblackNum, whiteNum = 0, 0k = h / wfor x in range(w):y1 = int(k * x)y2 = int((-k) * x + h - 1)# prevent overflowif 0 <= y1 <= (h - 1) and 0 <= y2 <= (h - 1):# first diagonal lineif gray[y1][x] <= bwThresh:blackNum += 1else:whiteNum += 1# second diagonal lineif gray[y2][x] <= bwThresh:blackNum += 1else:whiteNum += 1print(blackNum, whiteNum)if blackNum > whiteNum:print("black based image")else:print("white based image")if __name__ == "__main__":img = cv2.imread("../img/handbag.png")bwThresh = 127  # threshold value of black or whiteBorW_binary(img, bwThresh)BorW_not_binary(img, bwThresh)

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Python+OpenCV判断图像是黑底还是白底

前言

代码逻辑

代码说明

代码依赖

代码实现

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