import cv2 as cv
from staintools.tissue_masks.abc_tissue_locator import ABCTissueLocator
from staintools.utils.exceptions import TissueMaskException
from staintools.preprocessing.input_validation import is_uint8_image
class LuminosityThresholdTissueLocator(ABCTissueLocator):
@staticmethod
def get_tissue_mask(I, luminosity_threshold=0.8):
"""
Get a binary mask where true denotes pixels with a luminosity less than the specified threshold.
Typically we use to identify tissue in the image and exclude the bright white background.
:param I: RGB uint 8 image.
:param luminosity_threshold: Luminosity threshold.
:return: Binary mask.
"""
assert is_uint8_image(I), "Image should be RGB uint8."
I_LAB = cv.cvtColor(I, cv.COLOR_RGB2LAB)
L = I_LAB[:, :, 0] / 255.0 # Convert to range [0,1].
mask = L < luminosity_threshold
# Check it's not empty
if mask.sum() == 0:
raise TissueMaskException("Empty tissue mask computed")
return mask
