opencv23DtectGeomtrcShape.py

import cv2
import numpy as np

img = cv2.imread('shape.png')
imGrey = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)

_, thresh = cv2.threshold(imGrey, 240, 255, cv2.THRESH_BINARY)
contours, _ = cv2.findContours(thresh, cv2.RETR_TREE, cv2.CHAIN_APPROX_NONE)

for contour in contours:
    approx = cv2.approxPolyDP(contour, 0.01*cv2.arcLength(contour, True), True)
    cv2.drawContours(img, [approx], 0, (0, 0, 0), 5)
    x = approx.ravel() [0]
    y = approx.ravel() [1] -5
    if len(approx) == 3:
        cv2.putText(img, "Triangle", (x, y), cv2.FONT_HERSHEY_COMPLEX, 0.5, (0, 0 ,0))
    elif len(approx) == 4:
        (x1, y1, w, h) = cv2.boundingRect(approx)
        aspectRatio = float(w)/h
        print(aspectRatio)
        if aspectRatio >= 0.95 and aspectRatio <= 1.05:
            cv2.putText(img, "Square", (x, y), cv2.FONT_HERSHEY_COMPLEX, 0.5, (0, 0 ,0))
        else :
            cv2.putText(img, "Rectangle", (x, y), cv2.FONT_HERSHEY_COMPLEX, 0.5, (0, 0 ,0))

    elif len(approx) == 5:
        cv2.putText(img, "Pentagon", (x, y), cv2.FONT_HERSHEY_COMPLEX, 0.5, (0, 0 ,0))
    elif len(approx) == 10:
        cv2.putText(img, "Star", (x, y), cv2.FONT_HERSHEY_COMPLEX, 0.5, (0, 0 ,0))
    else :
        cv2.putText(img, "Circle", (x, y), cv2.FONT_HERSHEY_COMPLEX, 0.5, (0, 0 ,0))


cv2.imshow("shapes", img)
cv2.waitKey(0)
cv2.destroyAllWindows()