Color values for opencv detection

import cv2
import numpy as np
frame = cv2.imread("page.png", 1)

kernal = np.ones((5, 5), "uint8")

hsv = cv2.cvtColor(frame, cv2.COLOR_BGR2HSV)
lower_blue = np.array([110,50,50])# 80, 255, 0
upper_blue = np.array([130,255,255]) # 0, 77, 26


mask = cv2.inRange(hsv, lower_blue, upper_blue)


res = cv2.bitwise_and(frame, frame, mask=mask)

while True:
   cv2.imshow("PDF Page", res)
   if cv2.waitKey(10) & 0xFF == ord('q'):
      cv2.destroyAllWindows()
      break

JavaScript
​x
 
import cv2
import numpy as np
frame = cv2.imread("page.png", 1)
​
kernal = np.ones((5, 5), "uint8")
​
hsv = cv2.cvtColor(frame, cv2.COLOR_BGR2HSV)
lower_blue = np.array([110,50,50])# 80, 255, 0
upper_blue = np.array([130,255,255]) # 0, 77, 26
​
​
mask = cv2.inRange(hsv, lower_blue, upper_blue)
​
​
res = cv2.bitwise_and(frame, frame, mask=mask)
​
while True:
   cv2.imshow("PDF Page", res)
   if cv2.waitKey(10) & 0xFF == ord('q'):
      cv2.destroyAllWindows()
      break
​

This is a basic Detection of a specific color script in python taken from here. I am trying to work with “#34659F” color. I checked the above values, and they dont correspond to blue region. I check both the uppler and lower values and found that they dont correspond to blue values. I tried to select the upper and lower bound for “#34659F” from here but I am unable to get anything back.

So, I was wondering how those values are selected for any given color.

Answer

These are the values you are looking for.

lower_blue = np.array([60, 0, 0]) upper_blue = np.array([255, 206, 153])

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Answer