LuminanceL1Loss: A loss function which measures percieved brightness and
  colour differences
Dominic De Jonge
We introduce LuminanceL1Loss, a novel loss function designed to enhance the
performance of image restoration tasks. We demonstrate its superiority over MSE
when applied to the Retinexformer, BUIFD and DnCNN architectures. Our proposed
LuminanceL1Loss leverages a unique approach by transforming images into
grayscale and subsequently computing the MSE loss for both grayscale and color
channels. Experimental results demonstrate that this innovative loss function
consistently outperforms traditional methods, showcasing its potential in image
denoising and other related tasks in image reconstruction. It demonstrates
gains up to 4.7dB. The results presented in this study highlight the efficacy
of LuminanceL1Loss for various image restoration tasks.