lane_detection_image.py

import cv2
import numpy as np
import matplotlib.pyplot as plt

def make_coordinates(image,line_parameteres):
    slope,intercept = line_parameteres
    y1 = image.shape[0]
    y2 = int(y1*(5/7))
    x1 = int((y1 - intercept)/slope)
    x2 = int((y2 - intercept)/slope)
    return np.array([x1,y1,x2,y2])

def average_slope_intercept(image,lines):
    left_fit = []
    right_fit = []
    for line in lines:
        x1,y1,x2,y2 = line.reshape(4)
        parameters = np.polyfit((x1,x2),(y1,y2),1)
        slope = parameters[0]
        intercept = parameters[1]
        if slope < 0:
            left_fit.append((slope,intercept))
        else:
            right_fit.append((slope,intercept))
    left_fit_average = np.average(left_fit,axis = 0)
    right_fit_average = np.average(right_fit,axis = 0)
    left_line = make_coordinates(image,left_fit_average)
    right_line = make_coordinates(image,right_fit_average)
    return np.array([left_line,right_line])


def canny(image):
    gray = cv2.cvtColor(image,cv2.COLOR_RGB2GRAY)
    blur = cv2.GaussianBlur(gray,(5,5),0)
    canny = cv2.Canny(blur,50,150)
    return canny

def display_lines(image,lines):
    line_image =  np.zeros_like(image)
    if lines is not None:
        for x1,y1,x2,y2 in lines:
            cv2.line(line_image,(x1,y1),(x2,y2),(255,0,0),10)
    return line_image


def region_of_interest(image):
    height = image.shape[0]
    polygons = np.array([
    [(200,height),(1100,height),(550,250)]
    ])
    mask = np.zeros_like(image)
    cv2.fillPoly(mask,polygons,255)
    masked_image = cv2.bitwise_and(image,mask)
    return masked_image


image = cv2.imread('test_image.jpg')
lane_image = np.copy(image)
canny_image = canny(lane_image)
cropped_image = region_of_interest(canny_image)
lines = cv2.HoughLinesP(cropped_image,2, np.pi/180,100, np.array([]),minLineLength=40,maxLineGap = 5)
averaged_lines = average_slope_intercept(lane_image,lines)
line_image = display_lines(lane_image,averaged_lines)
combo_image = cv2.addWeighted(lane_image,0.8,line_image,1,1)
cv2.imshow("result",combo_image)
cv2.waitKey(0)