Hykilpikonna
129 lines
4.5 KiB
Python
Executable File
129 lines
4.5 KiB
Python
Executable File
"""CSC110 Fall 2021 Assignment 1, Part 4
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Instructions (READ THIS FIRST!)
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===============================
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Please follow the instructions in the assignment handout to complete this file.
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Copyright and Usage Information
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===============================
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This file is provided solely for the personal and private use of students
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taking CSC110 at the University of Toronto St. George campus. All forms of
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distribution of this code, whether as given or with any changes, are
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expressly prohibited. For more information on copyright for CSC110 materials,
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please consult our Course Syllabus.
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This file is Copyright (c) 2021 Mario Badr and Tom Fairgrieve.
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"""
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import random
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import a1_image
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def maximize_channels(old_pixel: tuple, value: int) -> tuple:
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"""Return a new pixel that has colour channels set to the larger of value or the corresponding
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colour channel in old_pixel.
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* Assumed that value is positive
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>>> example_pixel = (100, 12, 155)
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>>> maximize_channels(example_pixel, 128)
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(128, 128, 155)
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"""
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return tuple([max(chan, value) for chan in old_pixel])
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def divide_channels(old_pixel: tuple, denominator: int) -> tuple:
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"""Return a new pixel that has colour channels set to the quotient from dividing the
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corresponding colour channel in old_pixel by denominator.
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* Assumed that denominators are positive integers.
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>>> example_pixel = (100, 12, 155)
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>>> divide_channels(example_pixel, 2)
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(50, 6, 77)
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"""
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return tuple([chan // denominator for chan in old_pixel])
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def add_pepper(pixel_data: list, k: int) -> list:
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"""Return a new list of pixels formed from the corresponding pixels in pixel_data that has some
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randomly chosen black pixels.
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The chance that a new pixel will be black is based on k. The probability that a pixel is
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black is to be : 1 / (k + 1)
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Assume that k >= 0.
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You must use the divide_channels function (above).
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Hint: use the function random.choice to choose from a list of denominators. What denominator,
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passed to divide_channels, causes a pixel to not change its colour? What denominator causes a
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pixel to become black?
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Because of the randomness, we can't specify an exact doctest.
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"""
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return [divide_channels(pixel, random.choice([1] * k + [256])) for pixel in pixel_data]
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def add_salt(pixel_data: list, k: int) -> list:
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"""Return a new list of pixels formed from the corresponding pixels in pixel_data that has some
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randomly chosen white pixels.
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The chance that a new pixel will be white is based on k. The probability that a pixel is
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white is to be : 1 / (k + 1)
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Assume that k >= 0.
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You must use the maximize_channels function (above).
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Hint: use the function random.choice to choose from a list of values. What value, passed to
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maximize_channels, causes a pixel to not change its colour? What value causes a pixel to become
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white?
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Because of the randomness, we can't specify an exact doctest.
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"""
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return [maximize_channels(pixel, random.choice([0] * k + [255])) for pixel in pixel_data]
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def add_salt_and_pepper(pixel_data: list, k: int) -> list:
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"""Return a new list of pixels formed from the corresponding pixels in pixel_data
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that has some randomly chosen white pixels and some randomly chosen black pixels.
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You must use the add_pepper then add_salt functions, in that order, with both using noise
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probabilities determined by k.
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Because of the randomness, we can't specify an exact doctest.
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"""
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pixel_data = add_pepper(pixel_data, k)
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pixel_data = add_salt(pixel_data, k)
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return pixel_data
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def run_salt_and_pepper_example(source: str, destination: str, k: int) -> None:
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"""Add salt and pepper noise to an example image file at source and save the result in
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destination, where noisiness is a function of k.
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You can run this function with an image of your choice. Make sure the image is not too large or
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this will take a long time.
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"""
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original_pixel_data, width, height = a1_image.load_image(source)
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noisy_pixel_data = add_salt_and_pepper(original_pixel_data, k)
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a1_image.save_image(destination, noisy_pixel_data, width, height)
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if __name__ == '__main__':
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import doctest
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doctest.testmod()
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run_salt_and_pepper_example('images/horses.png', 'images/noisy-horses.png', 16)
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# When you are ready to check your work with python_ta, uncomment the following lines.
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# (Delete the "#" and space before each line.)
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import python_ta
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python_ta.check_all(config={
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'extra-imports': ['random', 'a1_image'],
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'max-line-length': 100
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})
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