edges = cv2.Canny(img, 100, 200, mask=mask)中mask=mask是什么意思

在OpenCV中，Canny函数用于边缘检测。其中的mask参数可以指定一个掩膜，用于限制边缘检测的范围。具体来说，mask参数是一个与原始图像大小相同的二值图像，它可以控制哪些像素会被用于边缘检测。如果某个像素在掩膜中对应的值为0，则Canny函数不会在该位置进行边缘检测。如果mask参数为None，则表示对整个图像进行边缘检测。在代码中，mask=mask表示使用与原始图像大小相同的掩膜进行边缘检测。

相关问题

import cv2 import numpy as np # 加载图像 img = cv2.imread('color_blind_road_2.png') # 转换为灰度图像 gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY) # 直线检测 edges = cv2.Canny(gray, 50, 150, apertureSize=3) lines = cv2.HoughLinesP(edges, 1, np.pi/180, threshold=100, minLineLength=100, maxLineGap=10) for line in lines: x1, y1, x2, y2 = line[0] cv2.line(img, (x1, y1), (x2, y2), (0, 0, 255), 2) # 阈值分割 ret, thresh = cv2.threshold(gray, 150, 255, cv2.THRESH_BINARY) thresh = cv2.medianBlur(thresh, 5) # 彩色连续性空间分割 hsv = cv2.cvtColor(img, cv2.COLOR_BGR2HSV) h, s, v = cv2.split(hsv) mask = cv2.inRange(h, 0, 20) | cv2.inRange(h, 160, 180) mask = cv2.bitwise_and(thresh, mask) # 纹理分割 gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY) texture = cv2.Canny(gray, 100, 200, apertureSize=3) texture = cv2.dilate(texture, None, iterations=3) texture = cv2.erode(texture, None, iterations=3) texture = cv2.bitwise_and(thresh, texture) # 显示结果 cv2.imshow('img', img) cv2.imshow('thresh', thresh) cv2.imshow('color', mask) cv2.imshow('texture', texture) cv2.waitKey(0) cv2.destroyAllWindows()改进代码

以下是对代码的一些改进建议：

1. 在 import 语句之间添加空格，使代码更易于阅读。

2. 使用函数封装代码，将不同的操作分别放入不同的函数中，可以使代码更加清晰和易于维护。

3. 添加异常处理，以避免因为文件路径或读取失败而导致程序崩溃。

4. 将一些常量或者需要调整的参数提取出来，以方便后续调整和修改。

5. 添加注释，以便代码的阅读和理解。

6. 使用 with 语句释放资源。

改进后的代码如下：

import cv2 
import numpy as np 

def load_image(path):
    """加载图片"""
    try:
        img = cv2.imread(path)
        return img
    except Exception as e:
        print(e)
        return None

def gray_transform(img):
    """灰度转换"""
    gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
    return gray

def edge_detection(img, threshold1=50, threshold2=150, apertureSize=3):
    """边缘检测"""
    edges = cv2.Canny(img, threshold1, threshold2, apertureSize=apertureSize)
    return edges

def line_detection(img, edges, threshold=100, minLineLength=100, maxLineGap=10):
    """直线检测"""
    lines = cv2.HoughLinesP(edges, 1, np.pi/180, threshold=threshold, minLineLength=minLineLength, maxLineGap=maxLineGap)
    for line in lines:
        x1, y1, x2, y2 = line[0]
        cv2.line(img, (x1, y1), (x2, y2), (0, 0, 255), 2)
    return img

def threshold_segmentation(img, threshold=150):
    """阈值分割"""
    ret, thresh = cv2.threshold(img, threshold, 255, cv2.THRESH_BINARY)
    thresh = cv2.medianBlur(thresh, 5)
    return thresh

def hsv_segmentation(img, lower_range, upper_range):
    """HSV颜色空间分割"""
    hsv = cv2.cvtColor(img, cv2.COLOR_BGR2HSV)
    mask = cv2.inRange(hsv, lower_range, upper_range)
    return mask

def color_segmentation(img, thresh, lower_range1=(0, 100, 100), upper_range1=(20, 255, 255), lower_range2=(160, 100, 100), upper_range2=(180, 255, 255)):
    """颜色分割"""
    mask1 = hsv_segmentation(img, lower_range1, upper_range1)
    mask2 = hsv_segmentation(img, lower_range2, upper_range2)
    mask = cv2.bitwise_or(mask1, mask2)
    mask = cv2.bitwise_and(thresh, mask)
    return mask

def texture_segmentation(img, thresh, threshold1=100, threshold2=200, iterations=3):
    """纹理分割"""
    gray = gray_transform(img)
    texture = cv2.Canny(gray, threshold1, threshold2, apertureSize=3)
    texture = cv2.dilate(texture, None, iterations=iterations)
    texture = cv2.erode(texture, None, iterations=iterations)
    texture = cv2.bitwise_and(thresh, texture)
    return texture

def show_image(img, winname='image'):
    """显示图片"""
    cv2.imshow(winname, img)
    cv2.waitKey(0)
    cv2.destroyAllWindows()

if __name__ == '__main__':
    # 加载图片
    img = load_image('color_blind_road_2.png')
    if img is None:
        exit()

    # 灰度转换
    gray = gray_transform(img)

    # 边缘检测
    edges = edge_detection(gray)

    # 直线检测
    img = line_detection(img, edges)

    # 阈值分割
    thresh = threshold_segmentation(gray)

    # 颜色分割
    mask = color_segmentation(img, thresh)

    # 纹理分割
    texture = texture_segmentation(img, thresh)

    # 显示结果
    show_image(img, 'img')
    show_image(thresh, 'thresh')
    show_image(mask, 'color')
    show_image(texture, 'texture')

import cv2 import numpy as np def CannyThreshold(lowThreshold): detected_edges = cv2.GaussianBlur(gray,(3,3),0) detected_edges = cv2.Canny(detected_edges,lowThreshold,lowThreshold*ratio,apertureSize = kernel_size) dst = cv2.bitwise_and(img,img,mask = detected_edges) # just add some colours to edges from original image. cv2.imshow('canny demo',dst) lowThreshold = 0 max_lowThreshold = 300 #最大阈值 ratio = 3 kernel_size = 3 #img = cv2.imread('AAA.jpg', cv2.IMREAD_GRAYSCALE) #注释此行图片不灰度化 img = cv2.imread("D:\xiao.jpg") #注释此行上行代码不注释图片灰度化 gray = cv2.imread("D:\xiao.jpg", cv2.IMREAD_GRAYSCALE) cv2.namedWindow('canny demo') cv2.createTrackbar('Min threshold','canny demo',lowThreshold, max_lowThreshold, CannyThreshold) CannyThreshold(0) # initialization if cv2.waitKey(0) == 27: cv2.destroyAllWindows()

这段代码是使用OpenCV库进行Canny边缘检测的操作，并且使用了滑动条来调节最小阈值。其中，首先对输入的图像进行了高斯模糊处理，然后使用Canny函数进行边缘检测，最后使用bitwise_and函数将原图像和检测出的边缘进行合并并显示出来。滑动条的回调函数是CannyThreshold，用于实时更新最小阈值并重新进行边缘检测和显示。如果按下ESC键，则关闭窗口。