swift-upscale

On-device 4× super-resolution via Real-ESRGAN (BSD-3) — recovers real detail (hair, texture, edges) rather than just sharpening. The "AI upscale" look.

• RealESRGANUpscaler — the Core ML model is a fixed 256×256 → 1024×1024 tile; upscale(_:progress:) tiles an arbitrary image, runs each tile 4×, and feather-blends the seams (no visible tile boundaries).

let upscaler = try RealESRGANUpscaler(modelURL: modelURL)
let big = upscaler.upscale(image) { p in print("\(Int(p * 100))%") }   // 4× the input

Model: LocalMuseAI/coreml-realesrgan-x4plus (RealESRGAN-x4plus, ~33 MB; variants: UltraSharp / x4v3 / x4v3-denoise / MangaJPEGLQ). Weights BSD-3. Fast enough for photos (seconds); video is an export-time pass (per-frame, minutes for short clips). Requirements: macOS 26 / iOS 26, Swift 6.2.

License

MIT — see LICENSE.

Bundled or downloaded models keep their own licences; see the notes above where a model is named.