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Fix psnr and corresponding test cases and rename variables (BugFix) #1487

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Fix psnr and corresponding test cases and rename variables (BugFix) #1487

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23 changes: 9 additions & 14 deletions checkbox-support/checkbox_support/scripts/psnr.py
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Original file line number Diff line number Diff line change
Expand Up @@ -52,33 +52,28 @@ def psnr_args() -> argparse.ArgumentParser:
return parser.parse_args()


def _get_psnr(I1: np.ndarray, I2: np.ndarray) -> float:
def _get_psnr(ref_img: np.ndarray, target_img: np.ndarray) -> float:
"""
Calculate the Peak Signal-to-Noise Ratio (PSNR) between two frames.

Args:
I1 (np.ndarray): Reference frame.
I2 (np.ndarray): Frame to be compared with the reference.
ref_img (np.ndarray): Reference frame.
target_img (np.ndarray): Frame to be compared with the reference.

Returns:
float: PSNR value indicating the quality of I2 compared to I1.
float: PSNR value indicating the quality of target_img compared to ref_img.
"""
# Calculate the absolute difference
s1 = cv2.absdiff(I1, I2)
s1 = cv2.absdiff(ref_img, target_img)
# cannot make a square on 8 bits
s1 = np.float32(s1)
# Calculate squared differences
s1 = s1 * s1
# Sum of squared differences per channel
# Sum of squared differences
sse = s1.sum()
# sum channels
if sse <= 1e-10:
# for small values return zero
return 0.0
else:
shape = I1.shape
mse = 1.0 * sse / (shape[0] * shape[1] * shape[2])
psnr = 10.0 * np.log10((255 * 255) / mse)
shape = ref_img.shape
mse = 1.0 * sse / (shape[0] * shape[1] * shape[2])
psnr = 10.0 * np.log10((255 * 255) / mse)
return psnr


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6 changes: 3 additions & 3 deletions checkbox-support/checkbox_support/tests/test_psnr.py
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Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,7 @@
from unittest.mock import patch, MagicMock
from argparse import Namespace
from io import StringIO
from math import inf

from checkbox_support.scripts.psnr import (
main,
Expand Down Expand Up @@ -60,13 +61,12 @@ def create_image(self, width, height, color):
def test_identical_images(self):
img1 = self.create_image(100, 100, 255)
img2 = self.create_image(100, 100, 255)
self.assertEqual(_get_psnr(img1, img2), 0.0)
self.assertEqual(_get_psnr(img1, img2), np.float32(inf))

def test_different_images(self):
img1 = self.create_image(100, 100, 255)
img2 = self.create_image(100, 100, 0)
self.assertNotEqual(_get_psnr(img1, img2), 0.0)
self.assertLessEqual(_get_psnr(img1, img2), 50.0)
self.assertEqual(_get_psnr(img1, img2), 0.0)

def test_similar_images(self):
img1 = self.create_image(100, 100, 125)
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