How to filter bar regions in Python.

To filter out rectangular areas, you can use the OpenCV library for image processing and analysis. Below is an example implemented in Python demonstrating how to use OpenCV to filter rectangular areas.

Firstly, install the OpenCV library.

pip install opencv-python

Next, load the image using the following code and perform preprocessing:

import cv2
import numpy as np

image = cv2.imread("image.jpg")  # 加载图像
gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)  # 转换为灰度图像
blurred = cv2.GaussianBlur(gray, (5, 5), 0)  # 对灰度图像进行高斯模糊

# 执行边缘检测
edges = cv2.Canny(blurred, 50, 150)

# 执行霍夫直线检测
lines = cv2.HoughLinesP(edges, 1, np.pi / 180, 100, minLineLength=100, maxLineGap=10)

Next, the detected lines can be further filtered as needed. For example, lines can be filtered based on their slope, keeping only those within a specific range.

filtered_lines = []
for line in lines:
    x1, y1, x2, y2 = line[0]
    slope = (y2 - y1) / (x2 - x1)  # 计算斜率
    if abs(slope) > 0.5 and abs(slope) < 2:  # 筛选斜率在0.5和2之间的直线
        filtered_lines.append(line)

Finally, the filtered straight lines can be drawn onto the original image for observation of the results.

for line in filtered_lines:
    x1, y1, x2, y2 = line[0]
    cv2.line(image, (x1, y1), (x2, y2), (0, 255, 0), 2)  # 绘制直线

cv2.imshow("Result", image)
cv2.waitKey(0)
cv2.destroyAllWindows()

In this way, you can find the rectangular area by filtering lines with slopes within a specific range. Adjusting the parameters based on the actual situation can yield better results.