Python with OpenCV in Colab for Color Detection and find Corner Detection

Import libs

import cv2
import os
import numpy as np
from matplotlib import pyplot as plt
from google.colab import drive

Read image and Show

img_path = ‘/content/gdrive/My Drive/Medium’
img = cv2.imread(os.path.join(img_path,’imagename.jpg’))
plt.imshow(img)
plt.show()

Convert BGR to HSV

hsv = cv2.cvtColor(img,cv2.COLOR_BGR2HSV)
plt.imshow(hsv)
plt.show()

Set Range HSV of Target and draw contours

กำหนดช่วงสีที่เราต้องการกัน

lower_green = np.array([119,27,45]) 
upper_green = np.array([208,255,255]) 
mask = cv2.inRange(hsv,lower_green,upper_green)
img2, contours, hierarchy = cv2.findContours(mask, cv2.RETR_TREE, cv2.CHAIN_APPROX_SIMPLE)
cv2.drawContours(img,contours,-1,(0,255,0),10)
plt.imshow(cv2.cvtColor(img,cv2.COLOR_BGR2RGB))
plt.show()

Create contours of image

img2, contours, hierarchy = cv2.findContours(mask, cv2.RETR_TREE, cv2.CHAIN_APPROX_SIMPLE)
n = len(contours)
for i in range(0,n):
  cnt = contours[i]
  per = cv2.arcLength(cnt,True)
  print('per = %.0f'%(per)) 
  if per > 4145:
    x,y,w,h = cv2.boundingRect(cnt)
    cv2.rectangle(img,(x,y),(x+w,y+h),(0,255,0),20)
plt.axis("off")
plt.imshow(cv2.cvtColor(img,cv2.COLOR_BGR2RGB))
plt.show()
  ################## perMAX = 4145 ##################