%run ../common.ipynb

img = imread('../MP.tiff')
# make a circle mask
r = 30
size = 2*r
x,y = np.meshgrid(range(size), range(size))
R = np.sqrt((x-r)**2+(y-r)**2)
mask = np.ones((size,size), bool)
mask[R>r] = 0
# discard values below 10
img[img<10]=0

# opening
imshow(ndimage.binary_opening(img, structure=mask))