Images with more than 3 channels

[ldv1]

Hi,

Some metrics (like SSIM) could be extended to 2D tensors (images) with more than 3 channels as the metrics are computed on a channel basis and then averaged over the channels. Is this the case in PIQA?

Best regards,
Laurent

[francois-rozet]

Hello @ldv1,

Indeed, SSIM, PSNR and TV don't impose a specific number of channels as the computed quantities are averaged over the channels. However, all other metrics rely on the chromatic (e.g. RGB) decomposition of pixels.

For SSIM, as mentioned in the documentation (see https://francois-rozet.github.io/piqa/piqa.ssim.html#piqa.ssim.SSIM) and in a previous discussion (#22), the number of expected channels can be modified with the n_channels parameter.

[ldv1]

Hi,
Sorry, this is something I overlooked.
Since this might be of interest to a wide audience, this information could be put in the main README.
Big thanks for your prompt answer.