How to fix data_range in ssim ?

[ChafikBak]

Hi @VainF

I am trying to train my cnn model with ssim loss.

So, I used 2 methods for training:

Method 1:

output_normalized = (output-min_val)/(max_val-min_val)
target_normalized = (target-min_val)/(max_val-min_val)
loss = 100*(1 - ssim(output_normalized, target_normalized,  data_range=1, size_average=True))

Method 2: loss = 100*(1 - ssim(output-min_val, target-min_val, data_range=max_val-min_val, size_average=True))

-Which method is better for training with ssim ?

-What is better:
to compute data_range for each output of the model or to use fixed data_range for all outputs ?

Thanks