the question of whether somebody of you knows similar applications that also run under linux and whether there will be an AI-based denoising tool in darktable in the future?
There is GitHub - trougnouf/nind-denoise: Image denoising using the Natural Image Noise Dataset but it’s really not user-friendly (clone the repository, download the models, and run the command for a given mostly processed (but not sharpened) image, then sharpen the image).
Darktable integration would require a couple of operations ((transposed) convolution and ReLU) written in C/OpenCL.
Per https://discuss.pixls.us/t/exporting-importing-photos-in-full-32-bit-representation-to-train-a-neural-network-for-image-denoising , It would also probably make most sense to retrain the model such that it applies earlier in the pipeline (probably right after demosaic, before or after exposure) rather than right before sharpening. For that the dataset would have to be reprocessed (the images need to be aligned then have the exposure matched between shots). I would be happy to release all of the raw files if someone is interested in doing the work but (as is usually the core issue) I will have no time to work on this in the foreseeable future.
Ideally we should also try different, simpler, architectures to minimize the runtime. (Though I am with @hyhno in that “denoising [in darktable] also takes a minute if you increase ‘search radius’ in ‘denoise (profiled)’ to a certain value.”)