def dvbv_index(img): # 将图像转换为灰度图像 gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY) # 计算细节方差 k = np.ones((3,3), np.uint8) gray_dilate = cv2.dilate(gray, k) gray_erode = cv2.erode(gray, k) detail_var = np.var(gray_dilate - gray_erode) # 计算背景方差 mean, std_dev = cv2.meanStdDev(gray) bg_var = std_dev**2 # 计算DV-BV指标 dvbv = detail_var / bg_var return dvbv 这段代码的原理是什么?怎么解释?
时间: 2024-03-30 13:40:01 浏览: 16
这段代码实现了计算DV-BV图像质量评价指标的功能。DV-BV是一种基于图像细节方差和背景方差的评价指标,用于评估图像的清晰度和噪声程度。具体原理如下:
1. 首先将彩色图像转换为灰度图像。
2. 计算细节方差:通过膨胀和腐蚀操作得到两幅图像,然后将两幅图像相减,得到细节图像。对细节图像进行方差计算,得到细节方差。
3. 计算背景方差:使用 `cv2.meanStdDev()` 函数计算灰度图像的均值和标准差,背景方差为标准差的平方。
4. 计算DV-BV指标:通过细节方差和背景方差的比值来评估图像的质量,DV-BV指标越大,图像的细节越清晰,噪声越小。
因此,这段代码的实现流程主要包括图像的灰度化、膨胀和腐蚀操作、方差计算和DV-BV指标计算。
相关问题
修改此代码使其可重复运行import pygame import sys from pygame.locals import * from robomaster import * import cv2 import numpy as np focal_length = 750 # 焦距 known_radius = 2 # 已知球的半径 def calculate_distance(focal_length, known_radius, perceived_radius): distance = (known_radius * focal_length) / perceived_radius return distance def show_video(ep_robot, screen): 获取机器人第一视角图像帧 img = ep_robot.camera.read_cv2_image(strategy="newest") 转换图像格式,转换为pygame的surface对象 img = cv2.cvtColor(img, cv2.COLOR_BGR2RGB) img = cv2.transpose(img) # 行列互换 img = pygame.surfarray.make_surface(img) screen.blit(img, (0, 0)) # 绘制图像 def detect_white_circle(ep_robot): 获取机器人第一视角图像帧 img = ep_robot.camera.read_cv2_image(strategy="newest") 转换为灰度图像 gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY) 进行中值滤波处理 gray = cv2.medianBlur(gray, 5) 检测圆形轮廓 circles = cv2.HoughCircles(gray, cv2.HOUGH_GRADIENT, 1, 50, param1=160, param2=40, minRadius=5, maxRadius=60) if circles is not None: circles = np.uint16(np.around(circles)) for circle in circles[0, :]: center = (circle[0], circle[1]) known_radius = circle 在图像上绘制圆形轮廓 cv2.circle(img, center, known_radius, (0, 255, 0), 2) 显示图像 distance = calculate_distance(focal_length, known_radius, known_radius) 在图像上绘制圆和距离 cv2.circle(img, center, known_radius, (0, 255, 0), 2) cv2.putText(img, f"Distance: {distance:.2f} cm", (center[0] - known_radius, center[1] - 10), cv2.FONT_HERSHEY_SIMPLEX, 0.5, (0, 255, 0), 2) cv2.imshow("White Circle Detection", img) cv2.waitKey(1) def main(): pygame.init() screen_size = width, height = 1280, 720 screen = pygame.display.set_mode(screen_size) ep_robot = robot.Robot() ep_robot.initialize(conn_type='ap') version = ep_robot.get_version() print("Robot version: {0}".format(version)) ep_robot.camera.start_video_stream(display=False) pygame.time.wait(100) clock = pygame.time.Clock() while True: clock.tick(5) # 将帧数设置为25帧 for event in pygame.event.get(): if event.type == QUIT: ep_robot.close() pygame.quit() sys.exit() show_video(ep_robot, screen) detect_white_circle(ep_robot) if name == 'main': main()
修改后的代码如下所示:
```python
import pygame
import sys
from pygame.locals import *
import robomaster
import cv2
import numpy as np
focal_length = 750 # 焦距
known_radius = 2 # 已知球的半径
def calculate_distance(focal_length, known_radius, perceived_radius):
distance = (known_radius * focal_length) / perceived_radius
return distance
def show_video(ep_robot, screen):
# 获取机器人第一视角图像帧
img = ep_robot.camera.read_cv2_image(strategy="newest")
# 转换图像格式,转换为pygame的surface对象
img = cv2.cvtColor(img, cv2.COLOR_BGR2RGB)
img = cv2.transpose(img) # 行列互换
img = pygame.surfarray.make_surface(img)
screen.blit(img, (0, 0)) # 绘制图像
def detect_white_circle(ep_robot):
# 获取机器人第一视角图像帧
img = ep_robot.camera.read_cv2_image(strategy="newest")
# 转换为灰度图像
gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
# 进行中值滤波处理
gray = cv2.medianBlur(gray, 5)
# 检测圆形轮廓
circles = cv2.HoughCircles(gray, cv2.HOUGH_GRADIENT, 1, 50, param1=160, param2=40, minRadius=5, maxRadius=60)
if circles is not None:
circles = np.uint16(np.around(circles
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:
```python
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')
```