Mencari Kontur Gambar menggunakan OpenCV

Kita melanjutkan pembahasan computer vision dengan mencari kontur image menggunakan OpenCV.

Source code mencari kontur segi empat dan lingkaran adalah seperti pada berikut ini

import cv2
import numpy as np

OPENCV_MAJOR_VERSION = int(cv2.__version__.split('.')[0])

img = cv2.pyrDown(cv2.imread("../images/hammer.jpg"))
asli = cv2.pyrDown(cv2.imread("../images/hammer.jpg"))


ret, thresh = cv2.threshold(cv2.cvtColor(img, cv2.COLOR_BGR2GRAY),
                            127, 255, cv2.THRESH_BINARY)

if OPENCV_MAJOR_VERSION >= 4:
    # OpenCV 4 or a later version is being used.
    contours, hier = cv2.findContours(thresh, cv2.RETR_EXTERNAL,
                                      cv2.CHAIN_APPROX_SIMPLE)
else:
    # OpenCV 3 or an earlier version is being used.
    # cv2.findContours has an extra return value.
    # The extra return value is the thresholded image, which (in
    # OpenCV 3.1 or an earlier version) may have been modified, but
    # we can ignore it.
    _, contours, hier = cv2.findContours(thresh, cv2.RETR_EXTERNAL,
                                         cv2.CHAIN_APPROX_SIMPLE)

for c in contours:
    # find bounding box coordinates
    x, y, w, h = cv2.boundingRect(c)
    cv2.rectangle(img, (x,y), (x+w, y+h), (0, 255, 0), 2)

    # find minimum area
    rect = cv2.minAreaRect(c)
    # calculate coordinates of the minimum area rectangle
    box = cv2.boxPoints(rect)
    # normalize coordinates to integers
    box = np.int0(box)
    # draw contours
    cv2.drawContours(img, [box], 0, (0, 0, 255), 3)

    # calculate center and radius of minimum enclosing circle
    (x, y), radius = cv2.minEnclosingCircle(c)
    # cast to integers
    center = (int(x), int(y))
    radius = int(radius)
    # draw the circle
    img = cv2.circle(img, center, radius, (0, 255, 0), 2)

cv2.imshow("asli", asli)

cv2.drawContours(img, contours, -1, (255, 0, 0), 1)
cv2.imshow("contours", img)

cv2.waitKey()
cv2.destroyAllWindows()

Source code ini bersumber dari https://github.com/PacktPublishing/Learning-OpenCV-4-Computer-Vision-with-Python-Third-Edition/blob/master/chapter03/contours_2.py .

Script ini akan menghasilkan tampilan seperti berikut ini

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