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hey guys i am using opencv 2.4 with python 2.7 on ubuntu14.04

I want to select multiple Region of Interest in an image is it possible to do so.

I want to do motion detection in only the area i have selected to do so any of the following theory can solve my problem but don't know how to implement any of them : -

  1. Mask the area in image which is not ROI

  2. After creating multiple ROI image how to add them such that all those ROI can be on the original location and remaining area be masked

vasu gupta
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  • in c++ the easiest way to work with ROIs are cv::Rect regions and subimages. Not sure whether these exist in python/numpy opencv – Micka Jun 29 '16 at 07:57

1 Answers1

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Yes it is possible to do so. Main Idea behind the solution would be creating a mask and setting it to 0 wherever you do not want the motion tracker to track.

If you are using numpythen you can create the mask and set the regions you do not want the detector to use, to zero. (Similar to cv::Rect(start.col, start.row, numberof.cols, numberof.rows) = 0 in c++)

In python using numpy you can create a mask, somewhat like this:

import numpy as np  

ret, frame = cap.read()
if frame.ndim == 3
    gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
elif frame.ndim == 4
    gray = cv2.cvtColor(frame, cv2.COLOR_BGRA2GRAY)
else:
    gray = frame

# create mask
mask = np.ones_like(gray)
mask[start_row:end_row, start_col:end_col] = 0
mask[another_starting_row:another_ending_row, another_start_col:another_end_col] = 0
# and so on you can create your own mask
# use for loops to create specific masks

It is a bit crude solution but will do the job. check numpy documentation (PDF) for more info.

Tomar
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