What upscaling can and can't do
Enlarging an image means creating pixels that weren't there. This tool uses Lanczos-3 resampling — the method used by professional image editors — which keeps edges noticeably crisper than the bilinear scaling most apps and browsers use, followed by an optional unsharp mask to restore apparent sharpness. The result is the best a mathematical enlargement can do: smooth, sharp-looking and faithful.
It won't invent detail. A blurry face stays a blurry face, only bigger. AI upscalers can "hallucinate" plausible detail such as skin texture or text, but they send your photo to a server and sometimes change what's in it; this tool never does either.
Good uses
- Meeting a minimum size for an upload form, marketplace listing or print service.
- Enlarging logos, icons and screenshots for slides without blocky pixels.
- Preparing a small image for printing: at 300 DPI, a 10×15 cm print needs about 1200×1800 pixels.
Use the slider on the preview to compare the original (scaled by the browser) with the enlarged version. Save as PNG to avoid adding compression artefacts, or WebP/JPG for a smaller file. Output is limited to about 40 megapixels to keep your browser responsive.
Are my files uploaded?
No. Upscaling runs with JavaScript and WebAssembly running in your browser tab. Your files are read from your device and the results are created on your device; nothing is sent to gratistools.be or anyone else, which is also why there are no queues, daily limits or watermarks. See the privacy page.