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Upscale Model

Welcome to the upscale rodeo. The Upscale Model node in ComfyUI isn’t just a pretty button — it’s the gateway to turning your smudgy potato of an image into a crispy, high-resolution marvel. If you've ever squinted at a generated image and whispered, "Enhance!", this is your node.

🔧 Node Overview​

Node Name: Upscale Model
Category: Image Processing / Post-processing
Purpose: Applies a learned upscaling model (e.g., ESRGAN variants, 4x-UltraSharp, etc.) to enhance the resolution and detail of an image. This is not your average resize — this is AI-powered pixel sorcery.

⚙️ Inputs and Outputs​

PortTypeDescription
imageIMAGEThe input image you wish to upscale. Must be an actual image tensor (not latent).
model_nameSTRING or COMBOThe name of the upscaling model to use.
scaleFLOATOptional (not all models respect this). Scale factor applied to the output. Most models are locked to 2x or 4x scaling.
upscaled_imageIMAGEThe glorious high-res output. Pipe this into a viewer or save node.

🧬 model_name — Deep Dive​

Ah yes, the critical part. Let’s unpack this.

The model_name dropdown (or combo input) lets you select from a list of pretrained super-resolution models. These models vary wildly in what they do, how they do it, and how heavy-handed they are about it.

Here are the usual suspects you might find:

Model NameDescription
4x-UltraSharpSuper crisp and detailed. Great for anime, illustrations, or detail-preserving upscaling. Can be a bit too sharp for photorealistic styles.
RealESRGAN_x4plusBalanced. Tries to be natural, realistic, and generic. Excellent choice for upscaling photos or general content.
RealESRGAN_x4plus_anime6BOptimized for anime-style linework. Don’t expect miracles on realistic content.
Lollypop_x4Often used for stylized or painterly work. Might add some “flair.”
BSRGANA blend of real-image fidelity with some enhancement. Doesn’t go overboard.
SwineMixUltra (example)Niche/experimental. Some community models can produce heavy enhancement or style transfer vibes. Check before using in production.

⚠️ Note: Available models depend on what you have downloaded and installed in your ComfyUI /models/upscale_models/ directory. If a model doesn’t show up, it’s probably not there. Blame your hard drive.

🛠️ Parameters​

model_name​

  • Type: Dropdown / Combo
  • Required: Yes (or nothing happens)
  • Function: Selects the upscaling model to apply.
  • Importance: Critical. Different models produce drastically different results.
  • Changing this affects:
    • The overall look (sharpness, color shift, artifacting)
    • Compatibility with content (e.g., anime vs real-life)
    • Speed (some models are heavier than others)

🧪 Workflow Setup​

Here’s how you’d typically use the Upscale Model node:

Basic Workflow:​

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[Image Node or VAE Decode] → [Upscale Model] → [Preview or Save Image]

Common Use Case:​

  1. Generate a 512x512 image via your favorite sampler.
  2. Decode latent to image (if it isn't already).
  3. Run it through Upscale Model with something like 4x-UltraSharp or RealESRGAN_x4plus.
  4. Save that high-res beauty.

💡 Recommended Use Cases​

ScenarioRecommended Model
Realistic portrait enhancementRealESRGAN_x4plus
Stylized art or anime4x-UltraSharp, anime6B
Photographic content (light touch)BSRGAN, RealESRGAN_x4plus
Sharp linework / inked illustrations4x-UltraSharp, anime6B
Stylized experimentsCommunity models (e.g. Lollypop)

🧞 Prompting Tips​

Okay, technically this isn’t a promptable node — but how you initially prompt your image does affect results here. Keep in mind:

  • If you want sharp, clean lines to be preserved: prompt with "high detail, crisp edges" and use a sampler like dpmpp_2m or euler.
  • Avoid muddy, soft images in your generation phase unless you're into that washed-out oil painting look after upscaling.
  • Faces and fine textures upscale better when the original image has decent base fidelity. Garbage in = high-res garbage out.

🚫 What-Not-To-Do-Unless-You-Want-a-Fire​

Listen, I get it — you're feeling bold, your render looks fire, and now you're about to go all-in on that upscale. But before you turn your GPU into a space heater, read this:

❌ Don’t Feed Latent Images Into This Node​

The Upscale Model node expects a decoded image, not a latent tensor. Feeding it latent data will either:

  • Crash your workflow
  • Produce terrifying glitch art
  • Or worse, silently do nothing while wasting your time

Fix: Use a VAE Decode node to convert your latent image to an actual image first.

❌ Don’t Chain Multiple Upscale Models Back-to-Back (Without Reason)​

Yes, you can technically chain two upscalers like RealESRGAN → 4x-UltraSharp… but why?

Unless you're intentionally stacking styles (and know what you're doing), you’ll end up with:

  • Oversharpened, crispy nightmares
  • Wacky color shifts
  • An image that looks like it’s been through a bootleg HDR filter from 2003

Fix: Pick one good model that fits your content. If it still looks bad, your input probably wasn’t good to begin with.

❌ Don’t Expect Upscaling To Fix Garbage​

Garbage in = garbage out. The AI isn’t a miracle worker. It’s more like an overzealous detail-enhancer:

  • Blurry image in? You’ll get high-res blur.
  • Anatomical horror? Now it’s a high-res anatomical horror.

Fix: Start with a clean, well-composed generation. Then upscale. Not the other way around.

❌ Don’t Ignore Model Purpose​

You wouldn’t use an anime upscaler on a photorealistic cityscape… unless your aesthetic is “vaporwave-meets-vomit.”

Each model has a target use case:

  • UltraSharp is not for subtle portraits.
  • anime6B is not for product photos.
  • SwineMixUltra... is for chaos. You’ve been warned.

Fix: Read the model descriptions. Use the right tool for the right job.

❌ Don’t Leave the Node Unconnected Then Wonder Why Nothing Happens​

Yes, you do need to actually plug in the image input and specify the model_name. Otherwise it’s just a pretty brick in your workflow.

📦 Pro Tips​

  • Use a Scale Image node before or after the Upscale Model if you want more fine-grained control over output dimensions.
  • Combine this with an Image Sharpen node if you're looking for razor-sharp realism (at your own risk).
  • For maximum control, try chaining latent upscaling + decoding + model-based upscaling.

🧾 Summary​

The Upscale Model node in ComfyUI is the power tool for anyone serious about taking their generations from thumbnail to print-quality. Whether you're enhancing character art, portraits, or sci-fi cityscapes, picking the right upscaling model is the difference between "eh, decent" and "wow, I’d put that on a wall."

Just remember: it's not magic. It's AI. Which means it can either polish a diamond or add sunglasses to your dog photo depending on your settings and your luck.