contours_processing.py

#!/usr/bin/env python

import numpy as np
import cv2

def read_rgb_image(image_name, show):
    rgb_image = cv2.imread(image_name)
    if show: 
        cv2.imshow("RGB Image",rgb_image)
    return rgb_image

def convert_rgb_to_gray(rgb_image,show,blur):
    gray_image = cv2.cvtColor(rgb_image, cv2.COLOR_BGR2GRAY)
    if show: 
        cv2.imshow("Gray Image",gray_image)
    if blur: rgb_image = cv2.GaussianBlur(rgb_image, (5, 5), 0)
    return gray_image

def convert_gray_to_binary(gray_image, adaptive, show):
    #choose THRESH_BINARY_INV or THRESH_BINARY depending on
    # which give a black background. 
    # We must get a black background for countours to work 
    if adaptive: 
        binary_image = cv2.adaptiveThreshold(gray_image, 
                            255, 
                            cv2.ADAPTIVE_THRESH_GAUSSIAN_C, 
                            cv2.THRESH_BINARY_INV, 5, 2)
    else:
        _,binary_image = cv2.threshold(gray_image,60,255,cv2.THRESH_BINARY_INV)
    if show:
        cv2.imshow("Binary Image", binary_image)
    #binary_image = cv2.erode(binary_image, None, iterations=2)
    #binary_image = cv2.dilate(binary_image, None, iterations=2)
    return binary_image    

def getContours(binary_image):      
    #_, contours, hierarchy = cv2.findContours(binary_image, 
    #                                          cv2.RETR_TREE, 
    #                                           cv2.CHAIN_APPROX_SIMPLE)
    contours, hierarchy = cv2.findContours(binary_image.copy(), 
                                            cv2.RETR_EXTERNAL,
	                                        cv2.CHAIN_APPROX_SIMPLE)
    return contours

def draw_contours(image, contours, image_name):
    index = -1 #means all contours
    thickness = 2 #thinkess of the contour line
    color = (255, 0, 255) #color of the contour line
    cv2.drawContours(image, contours, index, color, thickness)
    cv2.imshow(image_name,image)

def process_contours(binary_image, rgb_image, contours):
    black_image = np.zeros([binary_image.shape[0], binary_image.shape[1],3],'uint8')
    
    for c in contours:
        area = cv2.contourArea(c)
        perimeter= cv2.arcLength(c, True)
        ((x, y), radius) = cv2.minEnclosingCircle(c)
        cv2.drawContours(rgb_image, [c], -1, (150,250,150), 1)
        cv2.drawContours(black_image, [c], -1, (150,250,150), 1)
        cx, cy = get_contour_center(c)
        cv2.circle(rgb_image, (cx,cy),(int)(radius),(0,0,255),1)
        cv2.circle(black_image, (cx,cy),(int)(radius),(0,0,255),1)
        print ("Area: {}, Perimeter: {}".format(area, perimeter))
    print ("number of contours: {}".format(len(contours)))
    cv2.imshow("RGB Image Contours",rgb_image)
    cv2.imshow("Black Image Contours",black_image)

def get_contour_center(contour):
    M = cv2.moments(contour)
    cx=-1
    cy=-1
    if (M['m00']!=0):
        cx= int(M['m10']/M['m00'])
        cy= int(M['m01']/M['m00'])
    return cx, cy

def main():
    image_name = "images/shapes.png"
    #image_name = "images/shapes2.jpg"
    rgb_image = read_rgb_image(image_name, True)
    gray_image= convert_rgb_to_gray(rgb_image,True,True)
    binary_image = convert_gray_to_binary(gray_image, True, True)
    contours = getContours(binary_image)
    process_contours(binary_image, rgb_image,contours)

    cv2.waitKey(0)
    cv2.destroyAllWindows()

if __name__ == '__main__':
    main()



cv2.waitKey(0)
cv2.destroyAllWindows()