From Concept to Reality: Mastering Progressive Denoising and Super-Resolution Techniques

CN
ComfyUI.org
2025-03-31 11:18:36

1. Workflow Overview

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  • Purpose: Generates high-fidelity images with minimal "AI-like" artifacts through multi-stage sampling, super-resolution, and progressive denoising.

  • Key Techniques:

    • FP8 Low-Precision Model: Uses FLUX_FB8V1.safetensors (FP8 E4M3) for memory efficiency.

    • Two-Stage KSampler: Base generation β†’ Progressive denoising refinement.

    • Hybrid Upscaling: Combines RealESRGAN and latent space scaling (LatentUpscaleBy).

2. Core Models & Nodes

Model/Node

Function

Installation

FLUX_FB8V1 (FP8 UNET)

Low-VRAM high-quality generation

Manual download to models/unet

t5xxl_fp8 + clip_l

Dual CLIP for advanced text encoding

HuggingFace/CivitAI

RealESRGAN_x4

4x super-resolution

Load via UpscaleModelLoader

Custom Nodes

KSampler Gradually Adding More Denoise

Progressive denoising

Install efficiency-nodes-comfyui

Image Comparer (rgthree)

A/B image comparison

ComfyUI Manager β†’ rgthree

3. Workflow Structure

Group 1: Model Loading & Text Encoding

  • Input: Positive prompt (e.g., dragon girl...), negative prompt (auto-handled).

  • Output: Text conditioning.

  • Key Nodes:

    • DualCLIPLoader: Enhances prompt understanding.

    • LoraLoaderModelOnly: Applies LoRA 熬梦.safetensors (weight=0.7).

Group 2: Base Image Generation

  • Input: Resolution 768x1152, seed=randomize, sampler=DEIS.

  • Output: Initial latent image.

  • Key Nodes:

    • KSampler (Efficient): CFG=0.95, denoise=0.6.

    • VAEDecode: Decodes latent for preview.

Group 3: Super-Resolution & Refinement

  1. ImageUpscaleWithModel: 4x upscale via RealESRGAN.

  2. VAEEncodeTiled: Re-encodes upscaled image to latent space.

  3. LatentUpscaleBy: Secondary latent scaling (nearest-exact).

  4. Progressive KSampler: Denoise strength reduced (0.4β†’0.35).

Group 4: Result Comparison

  • Tool: Image Comparer for before/after sliding.

4. Inputs & Outputs

  • Inputs:

    • Required: Positive prompt, resolution (768x1152 recommended).

    • Optional: Seed (default random), LoRA weight (default=0.7).

  • Outputs:

    • Final image (PNG with metadata).

    • Comparison slides (via Image Comparer).

5. Notes

  1. VRAM: β‰₯10GB GPU (e.g., NVIDIA 30/40 series).

  2. Compatibility: Disable xformers for FP8 models.

  3. Troubleshooting:

    • CLIP encode failed β†’ Verify t5xxl_fp8 model path.

  4. Optimization: Use Tiled VAE plugin to reduce VRAM usage.