TheAlgorithms-Python

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"""
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Peak signal-to-noise ratio - PSNR
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    https://en.wikipedia.org/wiki/Peak_signal-to-noise_ratio
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Source:
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https://tutorials.techonical.com/how-to-calculate-psnr-value-of-two-images-using-python
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"""
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import math
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import os
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import cv2
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import numpy as np
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PIXEL_MAX = 255.0
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def peak_signal_to_noise_ratio(original: float, contrast: float) -> float:
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    mse = np.mean((original - contrast) ** 2)
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    if mse == 0:
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        return 100
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    return 20 * math.log10(PIXEL_MAX / math.sqrt(mse))
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def main() -> None:
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    dir_path = os.path.dirname(os.path.realpath(__file__))
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    # Loading images (original image and compressed image)
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    original = cv2.imread(os.path.join(dir_path, "image_data/original_image.png"))
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    contrast = cv2.imread(os.path.join(dir_path, "image_data/compressed_image.png"), 1)
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    original2 = cv2.imread(os.path.join(dir_path, "image_data/PSNR-example-base.png"))
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    contrast2 = cv2.imread(
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        os.path.join(dir_path, "image_data/PSNR-example-comp-10.jpg"), 1
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    )
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    # Value expected: 29.73dB
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    print("-- First Test --")
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    print(f"PSNR value is {peak_signal_to_noise_ratio(original, contrast)} dB")
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    # # Value expected: 31.53dB (Wikipedia Example)
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    print("\n-- Second Test --")
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    print(f"PSNR value is {peak_signal_to_noise_ratio(original2, contrast2)} dB")
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if __name__ == "__main__":
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    main()
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