如何使用 Python 检查视频中的邮筒和信箱？

Question

我需要构建一个工具，可以帮助我确定视频是否包含信箱或邮筒（两侧的黑线或白线），并查看该字母/邮筒是否占据视频的 10% 以上。 由于信箱要么是黑色的，要么是白色的，我想通过查找黑色或白色像素的列/行来明确检查边框是否为黑色（<5) or white (>250）。

我用 GUI 制作了一个脚本来上传视频，但它无法正常工作。它没有显示正确的百分比。我怎样才能做得更准确？ 这是我的代码：

from turtle import width
import cv2
import numpy as np
import tkinter as tk
from tkinter import filedialog

# Global variable to hold the result label
result_label = None

def calculate_border_size(video_path, border_pixels=20, black_threshold=5, white_threshold=250):
    # Open video capture
    cap = cv2.VideoCapture(video_path)

    # Check if the video capture is successfully opened
    if not cap.isOpened():
        raise ValueError("Error: Could not open video file.")

    # Initialize variables to store cumulative results
    black_rows_sum = 0
    white_rows_sum = 0
    frame_count = 0
    height, width = None, None

    while True:
        ret, frame = cap.read()

        if not ret:
            break

        if height is None or width is None:
            height, width = frame.shape[:2]

        # Extract the border regions
        border_regions = np.concatenate((frame[:, :border_pixels], frame[:, -border_pixels:]), axis=1)

        # Count black and white rows in the border regions
        black_rows = np.sum(np.sum(border_regions < black_threshold, axis=0) == frame.shape[0])
        white_rows = np.sum(np.sum(border_regions > white_threshold, axis=0) == frame.shape[0])

        # Accumulate results
        black_rows_sum += black_rows
        white_rows_sum += white_rows
        frame_count += 1

    cap.release()

    # Calculate the average black and white rows
    avg_black_rows = black_rows_sum / frame_count
    avg_white_rows = white_rows_sum / frame_count

   # Calculate the percentage of black rows compared to the whole screen height
    percentage_black_rows = (avg_black_rows / height) * 100
    percentage_white_rows = (avg_white_rows / height) * 100

    # Check if the percentage of black rows exceeds 20% of the screen height
    is_letterboxing = percentage_black_rows > 20 or percentage_white_rows > 20

    return is_letterboxing, percentage_white_rows, percentage_black_rows

# Function to handle the video upload button
def upload_video():
    video_path = filedialog.askopenfilename(filetypes=[("Video files", "*.mp4;*.avi")])
    if video_path:
        analyze_video(video_path)

# Function to analyze the video and display results
def analyze_video(video_path):
    global result_label  # Declare result_label as a global variable
    try:
        is_letterboxing, percentage_white_rows, percentage_black_rows = calculate_border_size(video_path)
        result_label.config(text=f"Is Letterboxing: {is_letterboxing}\nPercentage Black Rows: {percentage_black_rows}\nPercentage White Rows: {percentage_white_rows}")
    except ValueError as e:
        result_label.config(text=str(e))

# GUI setup
root = tk.Tk()
root.title("Video Analysis")

# Button to upload video
upload_button = tk.Button(root, text="Upload Video", command=upload_video)
upload_button.pack(pady=20)

# Label to display results
result_label = tk.Label(root, text="")
result_label.pack()

# Run the GUI
root.mainloop()

Answer 1

你做错了一件事。假设视频中有 300 帧，只有 60 帧有宽度 70 的黑条，其余帧没有黑条或白条。

 avg_black_rows = black_rows_sum / frame_count
    avg_white_rows = white_rows_sum / frame_count

   # Calculate the percentage of black rows compared to the whole screen height
    percentage_black_rows = (avg_black_rows / height) * 100
    percentage_white_rows = (avg_white_rows / height) * 100

你计算 B 的方式