Core Tools
Upscaling images 2× and 4×
Choose the right upscale mode, understand the local model download, inspect seam diagnostics, and avoid halos on transparent cutouts.
The image upscaler enlarges a picture entirely in your browser. The useful choice is not simply “2× or 4×”; it is which processing path matches the source.
Choose a source mode
- Photo is for camera images, compressed portraits, fur, and natural texture. It favours restoration over perfectly straight edges.
- Artwork or logo protects flat colour, text, and hard geometry from invented texture.
- Transparent cutout keeps the alpha edge attached to the restored colour instead of sharpening invisible black pixels behind it.
If you are unsure, start with Photo and inspect the preview at 100%. Upscaling cannot recover detail that was never captured, so compare eyes, text, and fine edges rather than judging only the larger dimensions.
Choose 2× or 4×
Use 2× when the source is already reasonably clear or when you need a modest marketplace or social-media size increase. It is faster and less likely to exaggerate compression artifacts.
Use 4× for genuinely small inputs. The best-quality path may download a model after you explicitly allow it. The model is cached on this device for later runs; your image is not uploaded with that request.
Transparent edges and halos
A cutout needs different sharpening from an opaque photo. NSS weights the sharpen pass by alpha so transparent neighbours cannot contribute hidden black colour to a fur or hair edge. It also upsamples alpha against the restored colour guide.
If an edge still looks too bright or dark:
- Open the result in the image editor.
- Inspect it over both a light and dark background.
- Use edge refinement sparingly.
- Export PNG or WebP with transparency and verify the saved file.
Tile seams
Large images are processed in overlapping tiles so the model does not exhaust browser memory. Adjacent tiles are feathered together, and the upscaler compares boundary changes with the nearby natural image gradient. A boundary that is much stronger than its local neighbours is attributed to tile stitching rather than to a real edge.
If a grid line remains visible, retry at 2× or reduce the source dimensions before a 4× run. Do not stack repeated sharpening passes; that can turn a small seam into a halo.
What stays local
The source image, tile pixels, previews, and export remain in browser memory. Only model files are fetched after consent. See Why AI tools download a model once for cache and storage controls.
Related
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