GTA5自动驾驶二 边沿检测

边沿检测采用Candy算法，比较经典，opencv自带

Candy算法的原理可以参见这篇博文：http://www.tuicool.com/articles/Y3q2Mf

整个流程是这样的：

1. 读取图像
2. 将图像转化为灰度图像
3. 运行高斯滤波
4. 运行Candy算子得到边沿

示例代码如下：

#! usr/bin/python
#coding=utf-8
#doing all the relevant imports
import matplotlib.pyplot as plt
import matplotlib.image as mpimg
import numpy as np
import cv2

image = mpimg.imread('exit-ramp.jpg')
gray = cv2.cvtColor(image,cv2.COLOR_RGB2GRAY)
# Define a kernel size for Gaussian smoothing / blurring
# Note: this step is optional as cv2.Canny() applies a 5x5 Gaussian internally
kernel_size = 5
blur_gray = cv2.GaussianBlur(gray,(kernel_size,kernel_size),10)
# Define parameters for Canny and run it
# NOTE: if you try running this code you might want to change these!
low_threshold = 1
high_threshold = 60
edges = cv2.Canny(blur_gray, low_threshold, high_threshold)

# Display the image

plt.subplot(221)
plt.imshow(image)
plt.subplot(222)
plt.imshow(gray,cmap='gray')
plt.subplot(223)
plt.imshow(blur_gray)
plt.subplot(224)
plt.imshow(edges, cmap='Greys_r')
plt.show()

运行结果：