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Enlarge a picture

Redraws the image at two or four times its size, filling in detail the original never had.

An upscaler is a model, and what it was trained on decides what it invents in the gaps. The photographic models keep skin and fabric plausible, while the anime models keep line art crisp instead of smearing it into gradients. The badge on each row is the factor that model enlarges by. Vectorize is in this group but has no badge, because it does not enlarge the picture. It redraws it as shapes and saves it as an SVG, a format that stays sharp at any size.
RealESRGAN x4
General-purpose upscaler for real photos.
RealESRGAN x2
General-purpose upscaler for real photos, a more conservative size increase.
RealESRGAN x4 (anime)
Tuned for anime and illustrated line art.
NMKD Siax (upscale)
Sharp detail recovery, suited to photos and fine textures.
4x AnimeSharp (upscale)
A sharpened upscaler for anime and illustrations.
4x Nomos 8k SC (upscale)
Trained on high-resolution photos; strong fine-detail sharpening.
4x LSDIR+ (upscale)
General-purpose photo upscaler tuned for natural, balanced detail.
4x Nomos WebPhoto RealPLKSR
Tuned for photos sourced from the web; handles compression artifacts well.
4x Nomos2 RealPLKSR Dysample
A newer Nomos model with smoother detail reconstruction.
4x Nomos2 HQ DAT2
A higher-quality Nomos variant for already-clean source photos.
2x Modern Spanimation v1
Tuned for modern (digital) animation frames.
Vectorize
Converts the image into a scalable SVG vector graphic.
Finishing · Interactive explorer Upscale
The same picture rendered at RealESRGAN_x4plusUpscale RealESRGAN_x4plus 2048 × 2048

The general-purpose choice, four times the size. Detail that was never rendered is invented plausibly rather than recovered, which is what every upscaler on this strip is doing.

Fetching the example images.

Upscaling during image generation

Examples

RealESRGAN x4 RealESRGAN_x4plus
The image that was submitted 512 × 512 Source What RealESRGAN x4 returned 2048 × 2048 Result

The horde's general-purpose four-times upscaler, and the one to reach for without a reason to reach for another.

RealESRGAN x2 RealESRGAN_x2plus
The image that was submitted 512 × 512 Source What RealESRGAN x2 returned 1024 × 1024 Result

The same family at two times rather than four, for when four is more picture than you want to pay for.

RealESRGAN x4 (anime) RealESRGAN_x4plus_anime_6B
The image that was submitted 512 × 512 Source What RealESRGAN x4 (anime) returned 2048 × 2048 Result

Trained on flat colour and line rather than photography. On a photographic source it is the wrong tool, which is exactly what a shared source makes visible.

NMKD Siax (upscale) NMKD_Siax
The image that was submitted 512 × 512 Source What NMKD Siax (upscale) returned 2048 × 2048 Result

A photographic four-times upscaler with a different idea of texture than the RealESRGAN pair.

4x AnimeSharp (upscale) 4x_AnimeSharp
The image that was submitted 512 × 512 Source What 4x AnimeSharp (upscale) returned 2048 × 2048 Result

Sharpens hard edges aggressively, which suits line art and overstates itself on skin.

Vectorize
The image that was submitted 512 × 512 Source What Vectorize returned Result

Filed under enlarge because it is the other answer to the same question: an SVG has no resolution to run out of. It redraws the picture in shapes rather than making the pixels bigger, so the fit is approximate.

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