Stitching images with transparency

[alex-rothwell]

I have two images which I want to stitch together. However, the part of the image that I am interested in is a circle in the centre, that is surrounded by a black border, as shown below.

Therefore, I've cropped the image to remove the black background to generate the below images.

As the area that is cropped from the image is now transparent, to read the image in using opencv requires the cv.IMREAD_UNCHANGED flag ie. cv.imread("images/preprocess/crop_img1.png", cv.IMREAD_UNCHANGED)

This works fine when reading in each individual image, but when running stitcher.stitch_verbose I get the following error:

panorama = stitcher.stitch_verbose([cv.imread("images/preprocess/crop_img1.png", cv.IMREAD_UNCHANGED),
                                    cv.imread("images/preprocess/crop_img2.png", cv.IMREAD_UNCHANGED)])

error: OpenCV(4.9.0) D:\a\opencv-python\opencv-python\opencv\modules\stitching\src\timelapsers.cpp:74: error: (-215:Assertion failed) img.type() == CV_16SC3 in function 'cv::detail::Timelapser::process'

Any ideas or workarounds? Thanks

[lukasalexanderweber]

You can just set --timelapse no or Stitcher stitcher = Stitcher(timelapse="no")

[alex-rothwell]

Thanks for the response Lukas. I'm getting the error with timelapse="no"