Roi custom OpenCV

Question

I have a video stream where I do the detection of people using Opencv and python. My ROI is rectangular, but I would like to make a custom shape as in the figure.

roi opencv

score 2 · Answer 1 · answered Jun 30 '19 at 10:55

It seems this is a stationary camera. If so, you can hard code the rectangular region of interest. You can then use a mask (created with for instance MS Paint) to black out everything outside of the custom shape.

Result:

Code:

    import cv2 
    # load image
    img = cv2.imread('image.jpg')
    # load mask
    mask = cv2.imread('roi_mask.png',0)
    # create subimage
    roi = img[120:350,150:580]
    # mask roi
    masked_roi = cv2.bitwise_and(roi,roi,mask=mask)
    # display result
    cv2.imshow('Roi',roi)
    cv2.imshow('Mask',mask)
    cv2.imshow('Result',masked_roi)
    cv2.waitKey(0)
    cv2.destroyAllWindows()

I used the code but it gave error (mtype == CV_8U || mtype == CV_8S). — Márcio, Jun 30 '19 at 23:12
Did you load the mask as a grayscale? Note the `,0)` in `mask = cv2.imread('roi_mask.png',0)` — J.D., Jul 01 '19 at 06:54

Roi custom OpenCV

1 Answers1