OpenCV (17) - Contour 유사 다각형 구하기

cv2.approxPolyDP(curve, epsilon, closed)

근사치 Contour 구하기

curve : Contour
epsilon : 최대 거리(클수록 Point 개수 감소)
closed : 폐곡선 여부

import cv2
import matplotlib.pyplot as plt

image = cv2.imread('digit_image.png')
image_gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
ret, thresh = cv2.threshold(image_gray, 230, 255, 0) # 픽셀 값이 230 보다 큰 경우 255, 원본은 배경이 하얀색
thresh = cv2.bitwise_not(thresh) # 검정과 하얀색 반전

contours = cv2.findContours(thresh, cv2.RETR_TREE, cv2.CHAIN_APPROX_SIMPLE)[0]
image = cv2.drawContours(image, contours, -1, (0,255,0), 4)

plt.imshow(cv2.cvtColor(image,cv2.COLOR_BGR2RGB))
plt.show()

contour = contours[0]
epsilon = 0.01 + cv2.arcLength(contour, True)
approx = cv2.approxPolyDP(contour, epsilon, True)
image = cv2.drawContours(image, [approx], -1, (0,255,0), 4)

plt.imshow(cv2.cvtColor(image,cv2.COLOR_BGR2RGB))
plt.show()