How to find mean value for a given part of an Image
contour, mean, opencv, python
Solution
There's easier way to get rectangle from an image in Python. Since `cv2` operates on NumPy arrays, you can use normal slicing (note, that `i` corresponds to `y` and `j` - to `x`, not the other way):
rect = image[i:i+h, j:j+w]
And taking mean is even simpler:
rect.mean()
Problem
I have "n" number of contour detected images(frame). I wants to find mean value for the rectangle portion of that image. (Instead of finding mean value for a full image, i need to calculate the mean value for the rectangle portion of that image.) I have rectangle's x,y position and width, height values. First Image x,y,w,h is 109,45 ,171,139 and second image x,y,w,h is 107,71,175,110. I get the values using the below code. `cv2.rectangle(frame, (x,y),(x+w,y+h), (0,0,255), 3)` I know using "ROI" concept we can do mean calculation. So, I referred some links. Ex. Get the ROI of two binary images and find difference of the mean image intesities between 2 ROI in python. But, I have confused with the parameter settings. Can anyone help me to resolve my problem ? Thanks in advance...