Image Upscaler — Enlarge Photos 2x/4x, with AI Upscaling on Our Server
Enlarge images 2x, 3x or 4x with smooth interpolation in your browser, or with Real-ESRGAN AI upscaling on our server (free Google sign-in). PNG, JPG or WebP output.
About Image Upscaler (AI)
An image upscaler enlarges a small image to a larger pixel size while trying to keep it sharp — useful when an old photo, a thumbnail, or a downscaled asset is the only source you have but the destination needs a higher resolution (a print, a large web banner, a presentation slide). The ZTools Image Upscaler has two modes. On this device, it enlarges the image 2x, 3x, 4x or to a custom width with smooth interpolation and an optional sharpen pass; nothing is uploaded, but no new detail is added. On our server, it runs Real-ESRGAN, an AI super-resolution model, at 2x or 4x: it rebuilds edges and texture far better than interpolation, needs a free Google sign-in, and the server deletes your image right after processing.
Use cases
- Restoring old family photos. A 600 px scan from a printed photo album. Upscale 4x with the AI mode for printing or framing, without the muddy look that plain interpolation produces.
- Recovering low-res screenshots. A screenshot taken on an old monitor needs to land on a 4K display. Upscale 2x with the AI mode to keep text edges crisper than interpolation does.
- Stock photo enlargement. A licensed image at 1000 px wide needs to fill a 2000 px banner. Upscale 2x; check for artifacts; touch up if needed.
- E-commerce product photo standardisation. Some product shots arrive at 800 px; the marketplace wants 2000 px. Upscale the small ones one at a time to meet the catalogue standard.
How it works
- Add your image. JPG, PNG, WebP and more. The AI mode takes up to 15 MB, and up to 1 megapixel for 2x or 0.5 megapixel for 4x. Sources under about 200 px on the short side soften noticeably.
- Choose where to process it. "On this device" enlarges it in your browser with no upload. "On our server" runs the Real-ESRGAN AI model and needs a free Google sign-in.
- Pick the scale. On this device: 2x, 3x, 4x or a custom width, with low, medium or high smoothing. On our server: 2x or 4x.
- Optional sharpen. On this device, a mild sharpen pass after enlarging makes edges crisper. Transparency is kept in both modes.
- Export. PNG (lossless, larger), JPG or WebP (smaller, lossy). The aspect ratio is kept.
Examples
Input: 500x500 thumbnail → 2000x2000 (4x, AI on our server)
Output: Rebuilt edges and texture, clearly sharper than interpolation
Input: 1200x800 photo → 2400x1600 (2x, on this device)
Output: Smooth 2x enlargement; edges stay soft unless you add the sharpen pass
Input: 800x600 screenshot of UI → 1600x1200 (2x, AI on our server)
Output: Upscaled UI with crisper text edges
Frequently asked questions
Will upscaling restore real detail?
No — it cannot recover information that was never captured. The AI mode infers plausible detail from what it learned in training, so it looks much sharper, but the new detail is a guess, not truth. The on-device mode only smooths the existing pixels. Treat upscaling as visual enhancement, not forensic restoration.
Which mode should I pick?
For photos, the AI mode on our server usually looks best. On this device is instant, private and limited only by your device memory, which suits UI screenshots, line art and large images.
Why does the upscaled image look muddy?
The source was already noisy or heavily JPG-compressed. The AI mode suppresses some JPG artifacts, but low-quality input cannot be fully fixed.
What is the maximum size?
On this device, your device memory is the limit: a modern laptop handles 4 MP images at 4x, while phones may stop at 2x for large inputs. The AI mode accepts up to 1 megapixel at 2x or 0.5 megapixel at 4x, because AI upscaling is heavy.
Does it remove watermarks?
No — and please respect copyright. The tool magnifies what is there; if a watermark is present, the upscale shows the same watermark.
Is my image uploaded to a server?
Only in the "On our server" mode, which sends it over HTTPS to our own processing server; the server deletes the image and the result right after processing. The "On this device" mode never uploads anything.
Pro tips
- Clean JPG artifacts and noise first when you can — upscaling magnifies them.
- For prints, upscale to 300 DPI of the printed size, not just "bigger".
- Compare the AI result with the on-device result — different photos prefer different approaches.
- Keep the original. You may want to re-upscale later with a better model.
- On this device, turn on the sharpen pass for crisper output before export.
Reviewed by Ahsan Mahmood · Last updated 2026-09-11 · Part of ZTools.
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