Files
2026-03-27 23:38:45 +08:00

2.4 KiB

Upscaling

Increase image resolution with AI enhancement.

Tools

Real-ESRGAN (Local, Free)

# Install
pip install realesrgan

# CLI
realesrgan-ncnn-vulkan -i input.jpg -o output.png -n realesrgan-x4plus
from realesrgan import RealESRGAN
import torch

model = RealESRGAN(torch.device("cuda"), scale=4)
model.load_weights("weights/RealESRGAN_x4plus.pth")

result = model.predict(input_image)

Models:

  • realesrgan-x4plus — General images (4x)
  • realesrgan-x4plus-anime — Anime/illustrations
  • realesr-general-x4v3 — Latest general model

Topaz Gigapixel AI

Commercial desktop app:

  • Up to 6x upscale
  • Face recovery built-in
  • Batch processing
  • ~$99 one-time

Magnific AI

curl -X POST "https://api.magnific.ai/v1/upscale" \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -F "image=@photo.jpg" \
  -F "scale=2"

Features:

  • "Creativity" slider adds AI detail
  • Best for artistic enhancement
  • ~$0.50/image

Replicate (Various Models)

import replicate

output = replicate.run(
    "nightmareai/real-esrgan:42fed1c4974146d4d2414e2be2c5277c7fcf05fcc3a73abf41610695738c1d7b",
    input={
        "image": open("photo.jpg", "rb"),
        "scale": 4,
        "face_enhance": True
    }
)

Scale Factors

Original 2x 4x 8x
512x512 1024 2048 4096
1080p 4K 8K
720p 1440p 4K 8K

Rule: Don't upscale beyond 4x in one pass for best quality.

When to Upscale

  • Print production — need 300 DPI
  • Large displays — billboards, banners
  • Old photos — restore low-res originals
  • AI-generated images — increase from 1024px

Pipeline Order

  1. Restore faces first — GFPGAN/CodeFormer
  2. Remove artifacts — denoise if needed
  3. Upscale — Real-ESRGAN or similar
  4. Sharpen — light unsharp mask if soft

Quality Tips

  • Don't over-upscale — 4x max in one pass
  • Match model to content — anime model for anime
  • Face enhance — enable for portraits
  • Check artifacts — AI can add weird textures
  • Preserve grain — add back film grain if needed

Comparison

Tool Scale Speed Quality Cost
Real-ESRGAN 4x Fast Good Free
Topaz 6x Medium Excellent $99
Magnific 2-4x Medium Best (creative) $$$
Replicate Varies Fast Good Per-use