Upscale Image: Sharp 4x Enlarge or AI 2x

How do I upscale an image?

Choose a picture and the Upscale tool opens on Sharp enlarge. Pick 2x, 3x or 4x, set Sharpen and press Enlarge; the new size shows before you start. For finer detail at 2x, switch to AI 2x and press Upscale 2x with AI. Then press Save picture.

1. Press Choose a picture, drop a file or paste one with Ctrl+V.
2. Pick 2x, 3x or 4x and a Sharpen amount, then press Enlarge. It takes a second or two.
3. For more detail, pick AI 2x and press Upscale 2x with AI. A progress bar shows the time left, and Stop cancels it.
4. Open Export to pick the format, then press Save picture.

To set an exact pixel size instead of a factor, use Resize Image. To make the bigger file lighter, run Compress Image afterward.

What is the difference between an AI image upscaler and a normal enlarge?

A normal enlarge spreads the existing pixels over a bigger grid and fills the gaps with smooth values. An AI upscaler has learned from many photo pairs what sharp detail looks like at a larger size, so it redraws edges, text and texture. It is much slower, and it cannot recover detail the picture never had.

Times for AI 2x leave out the start-up: loading the model took 28.2 seconds on WebGPU and 15.5 seconds on WebAssembly. We also tried a smaller 8-bit copy of the model: on WebAssembly it took 34.0 seconds to load and 187.4 seconds for the 500 x 500 picture, and on WebGPU it was slower still, so the site ships only the 32-bit file.

How big a picture can the AI upscale?

With WebGPU, AI 2x takes pictures up to 0.75 megapixels, about 175 seconds on our test laptop. With WebAssembly the limit is 0.25 megapixels, about 192 seconds. Phones that report 2 GB of memory or less get half. For larger pictures, Sharp enlarge goes up to 16 megapixels.

The model sees 128 pixel tiles that overlap by 16 pixels. In each overlap the two tiles are blended with straight ramps that add up to 1, so no seam shows where tiles meet. The WebGPU engine is a 23.9 MB download, fetched only when your browser has WebGPU.

Can upscaling enhance image quality?

It can make a clean small picture look sharper at a larger size. The Swin2SR model was trained on sharp photos that were made smaller, so it is best at undoing plain downsizing. It does little for camera noise, motion blur or heavy JPEG blocks, and it will not invent faces or text that are not readable.

For an old scan or a dark photo, first fix brightness and contrast in the Photo Editor Adjust tool, then upscale.

How does Sharp enlarge work?

Each new pixel is a weighted mix of the nearest original pixels, using the Lanczos3 kernel. A pixel half a step away gets weight 0.608 and one 1.5 steps away gets -0.135, a small negative weight that keeps edges crisp. An unsharp mask then lifts edge contrast by the Sharpen amount.

The weights for each output pixel always add up to 1, so flat areas keep their exact color. Sharpening skips differences under 2 levels, so smooth skies do not turn grainy.

Is the image upscaler private?

Yes. The AI model downloads once to your browser and runs on your device. Your picture never leaves it: there is no upload and no account. Sharp enlarge needs no download at all. AI 2x fetches the engine and the 7.7 MB model from this site, then keeps them in your browser cache.