Imitating the "magic wand" photoshop tool in OpenCV

Question

I'm trying to isolate the sky region from a series of grayscale images in OpenCV. All of the images are fairly similar: the top of the image is always a sky region, and is always a bright, gray-white colour. I've attempted contour-based approaches, and written my own algorithm to extract the line of the horizon and divide the image into two masks accordingly. However, I've noticed that the reliability of the magic wand tool in Photoshop on this image set is MUCH more accurate.

Here's the image that I'm processing:

and the result that I hope to achieve:

How can this be imitated in OpenCV?

Answer 1

I think what you're looking for is the grabcut algorithm