Image.point() this image using a reference table or function.
Syntax: Maps this image through a lookup table or function.
lut - A lookup table, containing 256 (or 65336 if self.mode == ”I” and mode == “L”) values per band in the image. A function can be used instead, it should take a single argument. The function is called once for each possible pixel value, and the resulting table is applied to all bands of the image.
mode - Output mode (default is same as input). In the current version, this can only be used if the source image has mode “L” or “P”, and the output has mode “1” or the source image mode is “I” and the output mode is “L”.
Returns: An Image object.
Another example: here the threshold value changes.