[coldtea]

>You can't train on decolorized images, because the neural network needs to learn how to predict color with a black and white image as context. Without color info, the model can't learn.

I think the parent means with delocorized images used to test the success and guide the training (since they can be readily compared with the colored image they resulted from which would be the perfect result).

Not to use decolorized images alone to train for coloring (which doesn't even make sense).