def addPolygonArea(self, polygon: QPolygonF):
# convert QImage into numpy array
imgArr = ImageViewerWithLabel.__qimage2narray(self.Image)
# convert image into gray mode if it's rgb mode.
gray = color.rgb2gray(imgArr)
# check if the polygon is inside the cropPolygon
polygon = polygon.intersected(self.cropPolygon)
# polygon to binary mask
mask = ImageViewerWithLabel.__QPolygon2Mask(gray.shape, polygon)
# __otsuWithMask2bw
bw = ImageViewerWithLabel.__otsuWithMask2bw(gray, mask)
# remove small objects
# morphology.remove_small_objects(bw, min_size=self.remove_small_objects, connectivity=2, in_place=True)
# morphology.remove_small_holes(bw, area_threshold=self.remove_small_holes, connectivity=2, in_place=True)
# binary image to label image
label = morphology.label(bw, connectivity=2)
self.addLabelMask(label)
