def encode_mask(mask):
"""
mask: input binary mask, type: uint8
output: full RLE encoding in the format: (x0, y0, w, h), RLE
first get minimal axis-aligned region which contains all positive pixels
extract this region from mask and calculate mask RLE within the region
output position and size of the region, dimensions of the full mask and RLE encoding
"""
# calculate coordinates of the top-left corner and region width and height (minimal region containing all 1s)
x_min, y_min, x_max, y_max = mask_bounds(mask)
# handle the case when the mask empty
if x_min is None:
return (0, 0, 0, 0), [0]
else:
tl_x = x_min
tl_y = y_min
region_w = x_max - x_min + 1
region_h = y_max - y_min + 1
# extract target region from the full mask and calculate RLE
# do not use full mask to optimize speed and space
target_mask = mask[tl_y:tl_y + region_h, tl_x:tl_x + region_w]
rle = mask_to_rle(np.array(target_mask))
return (tl_x, tl_y, region_w, region_h), rle
def convert(self, rtype: RegionType):
if rtype == RegionType.MASK:
return self.copy()
elif rtype == RegionType.RECTANGLE:
bounds = mask_bounds(self.mask)
return Rectangle(bounds[0] + self.offset[0], bounds[1] + self.offset[1],
bounds[2] - bounds[0], bounds[3] - bounds[1])
elif rtype == RegionType.POLYGON:
bounds = mask_bounds(self.mask)
if None in bounds:
return Polygon([(0, 0), (0, 0), (0, 0), (0, 0)])
return Polygon([
(bounds[0] + self.offset[0], bounds[1] + self.offset[1]),
(bounds[2] + self.offset[0], bounds[1] + self.offset[1]),
(bounds[2] + self.offset[0], bounds[3] + self.offset[1]),
(bounds[0] + self.offset[0], bounds[3] + self.offset[1])])
else:
raise ConversionException("Unable to convert mask region to {}".format(rtype), source=self)
def _optimize(self):
bounds = mask_bounds(self.mask)
if bounds[0] is None:
# mask is empty
self._mask = np.zeros((0, 0), dtype=np.uint8)
self._offset = (0, 0)
else:
self._mask = np.copy(self.mask[bounds[1]:bounds[3], bounds[0]:bounds[2]])
self._offset = (bounds[0] + self.offset[0], bounds[1] + self.offset[1])
def bounds(self):
bounds = mask_bounds(self.mask)
return bounds[0] + self.offset[0], bounds[1] + self.offset[1], bounds[
2] + self.offset[0], bounds[3] + self.offset[1]
