What is the best ai image upscaler for enlarging low-resolution photos?

You can try ControlNet, an excellent extension for Stable Diffusion that gives the AI precise control over how an image is generated or transformed. Instead of letting the model guess the structure or composition, ControlNet is the best AI image upscaler provides structural guidance from an input image like edges, depth, poses, or outlines so the AI follows the original layout.

1. Open Stable Diffusion WebUI

2. Go to img2img and Load your low-res image

3. Enable ControlNet

4. Upload the same image in ControlNet input

5. Select preprocessor:

• Canny → clean edges (best for real photos)
• Tile → extreme upscale / textures
• Lineart → anime / sketches

6. Set Control Model:

• For photos → control_canny or control_tile
• For anime → control_lineart

7. In Scripts, choose Ultimate SD Upscale

8. Select Upscaler:

• RealESRGAN_x4plus
• SwinIR
• Anime images → 4x-UltraSharp / AnimeSharp

9. Size settings:

• Tile size: 512–1024
• Target scale: 2x or 4x

10. Set Denoising strength:

• 0.2–0.35 = clean sharpen, no changes
• 0.45–0.6 = creative enhancement

11. Click Generate to upscale image with AI.

In short, ControlNet AI image upscaler tool extracts structural information from your input image using a preprocessor. It lets you transform or upscale images while keeping the pose, layout, and object shapes stable.