Omee Omee - 3 months ago 18
Python Question

How To Detect Red Color In OpenCV Python?

I am trying to detect red color from the video that's being taken from my webcam. The following code example given below is taken from OpenCV Documentation.
The code is given below:

import cv2
import numpy as np

cap = cv2.VideoCapture(0)


# Take each frame
_, frame =

# Convert BGR to HSV
hsv = cv2.cvtColor(frame, cv2.COLOR_BGR2HSV)

# define range of blue color in HSV
lower_blue = np.array([110,50,50])
upper_blue = np.array([130,255,255])

# Threshold the HSV image to get only blue colors
mask = cv2.inRange(hsv, lower_blue, upper_blue)

# Bitwise-AND mask and original image
res = cv2.bitwise_and(frame,frame, mask= mask)

k = cv2.waitKey(5) & 0xFF
if k == 27:


The line
lower_blue = np.array([110,50,50])
has the lower range Blue HSV value and the line
upper_blue = np.array([130,255,255])
has the higher range Blue HSV value. I have looked for the upper value and lower value of Red color on internet but I couldn't find it. It would be very helpful if anyone could tell the HSV value of Red for OpenCV (OpenCV H value ranges from 0 - 179).
Thanks a lot for help (In Advance).

I have also tried running the following to find the range of Red but I was unable to pick proper value maybe. What I tried was this(for red):

>>> green = np.uint8([[[0,255,0 ]]])
>>> hsv_green = cv2.cvtColor(green,cv2.COLOR_BGR2HSV)
>>> print hsv_green
[[[ 60 255 255]]]

This was also taken from OpenCV documentation.
Please tell me or help me find the RANGE of RED COLOR for OpenCV.


Running the same code for red seems to work:

>>> red = numpy.uint8([[[0,0,255]]])
>>> hsv_red = cv2.cvtColor(red,cv2.COLOR_BGR2HSV)
>>> print(hsv_red)
[[[  0 255 255]]]

And then you can try different colors that appear reddish. Beware that the red range includes both numbers slightly greater than 0 and numbers slightly smaller than 179 (e.g. red = numpy.uint8([[[0,31,255]]]) results in [[[ 4 255 255]]] whereas red = numpy.uint8([[[31,0,255]]]) results in [[[176 255 255]]].