peak_signal_to_noise_ratio.py

"""
Peak signal-to-noise ratio - PSNR
 https://en.wikipedia.org/wiki/Peak_signal-to-noise_ratio
Source:
https://tutorials.techonical.com/how-to-calculate-psnr-value-of-two-images-using-python
"""

importmath
importos

importcv2
importnumpyasnp

PIXEL_MAX=255.0


defpeak_signal_to_noise_ratio(original: float, contrast: float) ->float:
mse=np.mean((original-contrast) **2)
ifmse==0:
return100

return20*math.log10(PIXEL_MAX/math.sqrt(mse))


defmain() ->None:
dir_path=os.path.dirname(os.path.realpath(__file__))
# Loading images (original image and compressed image)
original=cv2.imread(os.path.join(dir_path, "image_data/original_image.png"))
contrast=cv2.imread(os.path.join(dir_path, "image_data/compressed_image.png"), 1)

original2=cv2.imread(os.path.join(dir_path, "image_data/PSNR-example-base.png"))
contrast2=cv2.imread(
os.path.join(dir_path, "image_data/PSNR-example-comp-10.jpg"), 1
 )

# Value expected: 29.73dB
print("-- First Test --")
print(f"PSNR value is {peak_signal_to_noise_ratio(original, contrast)} dB")

# # Value expected: 31.53dB (Wikipedia Example)
print("\n-- Second Test --")
print(f"PSNR value is {peak_signal_to_noise_ratio(original2, contrast2)} dB")


if__name__=="__main__":
main()