Artificial Neural Networks for Image Colorization

Hello! At the moment, I'm learning about artificial neural networks for colorizing black and white images. After reading enough literature and considering many examples, I had one, maybe stupid, question: how can a convolutional neural network, like U-net, colorize images? From many articles, I realized that this architecture is able to extract features from an image by applying a convolution operation and subsequently combine them. But where do the a and b color channels come from (we are talking about …

artificial artificial neural networks deeplearning image networks neural networks