checking the Colors Opencv Python - python-2.7

Question

I have a code to detect two colors green and blue. I want to check if
green color is detected to print a massage and if blue color is detected to print another message too
Here is the Code:
import cv2
import numpy as np
cap = cv2.VideoCapture(0)
while(1):
# Take each frame
_, frame = cap.read()
# 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])
lower_green = np.array([50, 50, 120])
upper_green = np.array([70, 255, 255])
green_mask = cv2.inRange(hsv, lower_green, upper_green) # I have the Green threshold image.
# Threshold the HSV image to get only blue colors
blue_mask = cv2.inRange(hsv, lower_blue, upper_blue)
mask = blue_mask + green_mask
############this is the Error ####################
if mask==green_mask:
print "DOne"
################################################
# Bitwise-AND mask and original image
res = cv2.bitwise_and(frame,frame, mask= mask)
cv2.imshow('frame',frame)
cv2.imshow('mask',mask)
cv2.imshow('res',res)
k = cv2.waitKey(5) & 0xFF
if k == 27:
break
cv2.destroyAllWindows()
Running the above code gives me following error:
if mask==green_mask:
ValueError: The truth value of an array with more
than one element is ambiguous. Use a.any() or a.all()
Any ideas how to fix this?

Answer 1

On comparing if mask==green_mask returns an array of boolean value of their dimension which can not satisfy an if condition which require a single boolean.
You need to use a function which will return true if matrix mask and green_mask are all same and return false otherwise. That function should be called under this if condition.
Edit:
Replace the code with
if np.array_equal(mask, green_mask):
It will fix your issue.