How to Upscale an Image with AI (Free)
Got an old, blurry, or just plain small photo you wish looked sharper? Here's how to enlarge it 4x and clean it up with AI, right in your browser — no software, no upload to a third-party server.
Steps
- Upload your photo at Stelluna's AI Image Upscaler — JPG, PNG, or WEBP, up to 15MB.
- Click "Upscale & Sharpen." The first time you use it, the AI model downloads to your browser (about 64MB, one-time only).
- Wait for processing — the AI runs entirely on your device, no file is ever uploaded anywhere.
- Download the upscaled result, now 4x the width and height of the original.
Ready to try it? Free, instant, your photo never leaves your device.
Open AI Image UpscalerHow does AI upscaling work?
Traditional resizing just stretches existing pixels, which makes images blurrier the bigger you go. AI upscaling uses a neural network (in this case, a Real-ESRGAN model) trained on millions of photos to predict the sharp details that a higher-resolution version would actually contain — hair strands, skin texture, fine edges — instead of just smearing what's already there. The result looks genuinely sharper, not just bigger.
FAQ
Is it free?
Yes — no account, no watermark, no limit on how many photos you upscale.
Does my photo get uploaded anywhere?
No. The AI model runs entirely inside your browser using WebGPU or WebAssembly — the photo is never sent to a server.
Why does the first upscale take longer?
The AI model (~64MB) has to download to your browser the first time. After that, your browser caches it, so it's much faster on repeat visits.
Is there a size limit?
Yes — input is capped at 480px on the longest side to keep processing time reasonable. Larger photos are automatically downscaled first, then upscaled 4x from there.