python 获取图片内容的坐标代码（图片格式为png）

# coding:utf-8
import cv2
import numpy as np
from PIL import Image
def get_transparency_location(image):
    '''获取基于透明元素裁切图片的左上角、右下角坐标
    '''
    # 1. 扫描获得最左边透明点和最右边透明点坐标
    #image = cv2.cvtColor(image, cv2.COLOR_BGR2BGRA) #图片为jpg格式时使用此行代码
    height, width, channel = image.shape  # 高、宽、通道数
    assert channel == 4  # 无透明通道报错
    first_location = None  # 最先遇到的透明点
    last_location = None  # 最后遇到的透明点
    first_transparency = []  # 从左往右最先遇到的透明点，元素个数小于等于图像高度
    last_transparency = []  # 从左往右最后遇到的透明点，元素个数小于等于图像高度
    for y, rows in enumerate(image):
        for x, BGRA in enumerate(rows):
            alpha = BGRA[3]
            if alpha != 0:
                if not first_location or first_location[1] != y:  # 透明点未赋值或为同一列
                    first_location = (x, y)  # 更新最先遇到的透明点
                    first_transparency.append(first_location)
                last_location = (x, y)  # 更新最后遇到的透明点
        if last_location:
            last_transparency.append(last_location)

    # 2. 矩形四个边的中点
    top = first_transparency[0]
    bottom = first_transparency[-1]
    left = None
    right = None
    for first, last in zip(first_transparency, last_transparency):
        if not left:
            left = first
        if not right:
            right = last
        if first[0] < left[0]:
            left = first
        if last[0] > right[0]:
            right = last

    # 3. 左上角、右下角
    upper_left = (left[0], top[1])  # 左上角
    bottom_right = (right[0], bottom[1])  # 右下角
    return upper_left[0], upper_left[1], bottom_right[0], bottom_right[1]

if __name__ == '__main__':
    img = r'C:\Users\test\Desktop\png\f\04-23.png';#图片地址(路径不支持中文)
    image = cv2.imread(img, cv2.IMREAD_UNCHANGED)  # 读取图片地址
    #返回图片内容坐标
    box = get_transparency_location(image)
    print(box);