Tight concave hull around 1-components in binary image

Question

I have a binary NIfTI image, i.e., an image of zeros (black) and ones (white) similar to this:

I've been trying for hours to create a tight hull around these white 1-components, so that in the end all pixels inside this hull are ones (white).

In the forum I came across the hint morphsnakes and this code snippet with this result:

def test_concave():
# Load the image.
imgcolor = imread("testimages/concave_hull.jpg")/255.0
img = rgb2gray(imgcolor)

# g(I)
gI = morphsnakes.gborders(img, alpha=1000, sigma=7)

# Morphological GAC. Initialization of the level-set.
mgac = morphsnakes.MorphGAC(gI, smoothing=3, threshold=0.55, balloon=-1)
mgac.levelset = circle_levelset(img.shape, (50, 199), 200)

# Visual evolution.
ppl.figure()
morphsnakes.evolve_visual(mgac, num_iters=62, background=imgcolor)

if __name__ == '__main__':
    print """"""
    test_concave()
    ppl.show()

Unfortunately, I can't get the script to work, no matter which package (that are omitted in the script) I include. Can you please support me or offer an equivalent method?