contour getting start

Contours : Getting Started

Goal

• Understand what contours are.
• Learn to find contours, draw contours etc
• You will see these functions : cv2.findContours(), cv2.drawContours()

import numpy as np
import cv2

im = cv2.imread('test.jpg')
imgray = cv2.cvtColor(im,cv2.COLOR_BGR2GRAY)
ret,thresh = cv2.threshold(imgray,127,255,0)
dst , contours, hierarchy = cv2.findContours(thresh,cv2.RETR_TREE,cv2.CHAIN_APPROX_SIMPLE)

To draw all the contours in an image:


cv2.drawContours(img, contours, -1, (0,255,0), 3)

To draw an individual contour, say 4th contour:

cv2.drawContours(img, contours, 3, (0,255,0), 3)

But most of the time, below method will be useful:


cnt = contours[4]
cv2.drawContours(img, [cnt], 0, (0,255,0), 3)

Reference : http://docs.opencv.org/3.0-beta/doc/py_tutorials/py_imgproc/py_contours/py_contours_begin/py_contours_begin.html#contours-getting-started