bloc97/anime4k

Anime4K is an open-source set of algorithms that upscale anime video in real time, so a 1080p episode can be played on a 4K screen and look better without first having to re-encode the file. The README's argument for doing it this way is that re-encoding anime to 4K takes huge amounts of disk space, can introduce artefacts, and is not reversible, while real-time upscaling preserves the original file and lets each viewer choose how to watch it. Technically it is a collection of fast image-processing shaders, distributed as GLSL code that you load into a video player such as MPV, IINA, or Plex. The README provides per-platform install instructions for Windows, Linux, and Mac. Internally the shaders combine convolutional neural network upscalers tuned for line-art, deblurring shaders, denoising algorithms (a bilateral mode and CNN variants), and corrections for badly resampled anime. The most recent version adds a line-reconstruction step that explicitly corrects the visual distribution shift in 1080p anime caused by low-quality compositing, so that traditional super-resolution algorithms can work across a wider variety of shows. Someone would use Anime4K when watching 1080p anime on a high-resolution display and wanting it sharpened on the fly without storing a separate upscaled copy. The README is explicit about its limits: it is optimised for native 1080p encoded with h.264, h.265, or VC-1, and is not intended for 720p, 480p, or older material, where heavyweight non-real-time approaches like waifu2x or Real-ESRGAN are better. The README also lists downstream projects that wrap it, including Magpie, Anime4KMetal, Anime4KCPP, video2x, and a WebGPU port.