Peak Signal-to-Noise Ratio (PSNR)

Module Interface

class torchmetrics.PeakSignalNoiseRatio(data_range=None, base=10.0, reduction='elementwise_mean', dim=None, **kwargs)

Computes Computes Peak Signal-to-Noise Ratio (PSNR):

Where denotes the mean-squared-error function.

As input to forward and update the metric accepts the following input

• preds (Tensor): Predictions from model of shape (N,C,H,W)

• target (Tensor): Ground truth values of shape (N,C,H,W)

As output of forward and compute the metric returns the following output

• psnr (Tensor): if reduction!='none' returns float scalar tensor with average PSNR value over sample else returns tensor of shape (N,) with PSNR values per sample

Parameters

• data_range (Optional[float]) – the range of the data. If None, it is determined from the data (max - min). The data_range must be given when dim is not None.

• base (float) – a base of a logarithm to use.

• reduction (Literal[‘elementwise_mean’, ‘sum’, ‘none’, None]) –

  a method to reduce metric score over labels.

  • 'elementwise_mean': takes the mean (default)

  • 'sum': takes the sum

  • 'none' or None: no reduction will be applied

• dim (Union[int, Tuple[int, ...], None]) – Dimensions to reduce PSNR scores over, provided as either an integer or a list of integers. Default is None meaning scores will be reduced across all dimensions and all batches.

• kwargs (Any) – Additional keyword arguments, see Advanced metric settings for more info.

Raises

ValueError – If dim is not None and data_range is not given.

Example

>>> from torchmetrics import PeakSignalNoiseRatio
>>> psnr = PeakSignalNoiseRatio()
>>> preds = torch.tensor([[0.0, 1.0], [2.0, 3.0]])
>>> target = torch.tensor([[3.0, 2.0], [1.0, 0.0]])
>>> psnr(preds, target)
tensor(2.5527)

Initializes internal Module state, shared by both nn.Module and ScriptModule.

Functional Interface

torchmetrics.functional.peak_signal_noise_ratio(preds, target, data_range=None, base=10.0, reduction='elementwise_mean', dim=None)

Computes the peak signal-to-noise ratio.

Parameters

• preds (Tensor) – estimated signal

• target (Tensor) – groun truth signal

• data_range (Optional[float]) – the range of the data. If None, it is determined from the data (max - min). data_range must be given when dim is not None.

• base (float) – a base of a logarithm to use

• reduction (Literal[‘elementwise_mean’, ‘sum’, ‘none’, None]) –

  a method to reduce metric score over labels.

  • 'elementwise_mean': takes the mean (default)

  • 'sum': takes the sum

  • 'none' or None``: no reduction will be applied

• dim (Union[int, Tuple[int, ...], None]) – Dimensions to reduce PSNR scores over provided as either an integer or a list of integers. Default is None meaning scores will be reduced across all dimensions.

Return type

Tensor

Returns

Tensor with PSNR score

Raises

ValueError – If dim is not None and data_range is not provided.

Example

>>> from torchmetrics.functional import peak_signal_noise_ratio
>>> pred = torch.tensor([[0.0, 1.0], [2.0, 3.0]])
>>> target = torch.tensor([[3.0, 2.0], [1.0, 0.0]])
>>> peak_signal_noise_ratio(pred, target)
tensor(2.5527)

Note

Half precision is only support on GPU for this metric