viqa.fr_metrics.psnr.PSNR

class viqa.fr_metrics.psnr.PSNR(data_range=255, normalize=False, **kwargs)[source]

Class to calculate the peak signal-to-noise ratio (PSNR) between two images.

score_val

PSNR score value of the last calculation.

Type:

float

parameters

Dictionary containing the parameters for PSNR calculation.

Type:

dict

Parameters:

  • data_range ({1, 255, 65535}, default=255) – Data range of the returned data in data loading. Is used for image loading when normalize is True and for the PSNR calculation. Passed to viqa.utils.load_data() and score().

  • normalize (bool, default False) – If True, the input images are normalized to the data_range argument.

  • **kwargs (optional) – Additional parameters for data loading. The keyword arguments are passed to viqa.utils.load_data().

  • chromatic (bool, default False) – If True, the input images are expected to be RGB images. If False, the input images are converted to grayscale images if necessary.

Raises:

ValueError – If data_range is not set.

Notes

data_range for image loading is also used for the PSNR calculation and therefore must be set. The parameter is set through the constructor of the class and is passed to score().

score(img_r, img_m)[source]

Calculate the peak signal-to-noise ratio (PSNR) between two images.

Parameters:

  • img_r (np.ndarray or Tensor or str or os.PathLike) – Reference image to calculate score against.

  • img_m (np.ndarray or Tensor or str or os.PathLike) – Distorted image to calculate score of.

Returns:

score_val – PSNR score value.

Return type:

float

export_results(path, filename)

Export the score to a csv file.

Parameters:

  • path (str) – The path where the csv file should be saved.

  • filename (str) – The name of the csv file.

Notes

The arguments get passed to viqa.utils.export_results().

load_images(img_r, img_m)

Load the images and perform checks.

Parameters:

  • img_r (np.ndarray, viqa.ImageArray, torch.Tensor, str or os.PathLike) – The reference image.

  • img_m (np.ndarray, viqa.ImageArray, torch.Tensor, str or os.PathLike) – The modified image.

Returns:

print_score(decimals=2)[source]

Print the PSNR score value of the last calculation.

Parameters:

decimals (int, default=2) – Number of decimal places to print the score value.

Warns:

RuntimeWarning – If score_val is not available.