CODEWITHSUNDEEP
pythonnumpyrgbopencvroi
Zako
Zako

Reputation: 71

How do I measure RGB mean in a unique ROI?

I have two images, an analysis image and an ROI Mask image (the ROI Mask image is below).

What I want to do is to measure the RGB mean value in an area of the analysis image selected by the ROI Mask image. I am doing this by using a for loop but it takes too long.

Is there any way to make this simpler?

import cv2
import numpy as np
from statistics import mean
img=cv2.imread("Analysis.jpg", 1)
mask=cv2.imread("ROI_Mask.jpg", 0)
height = im.shape[0]
width = im.shape[1]
R_value=[]
G_value=[]
B_value=[]
for x in range(width):
 for y in range(height):
  if mask[y][x]!=0:
   b,g,r=img[y][x]
   R_value.append(r)
   G_value.append(g)
   B_value.append(b)
  else:
   pass
print(np.mean(R_value))

ROI Mask Image

Upvotes: 5

Views: 350

Answers (1)

Tonechas
Tonechas

Reputation: 13743

You can vectorize your code through boolean indexing like this:

b = mask > 0
B_value, G_value, R_value = img[b].T
print(R_value.mean())

Upvotes: 2

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