Extensions/ComfyUI Fast Mosaic Detector
ComfyUI Extension

ComfyUI Fast Mosaic Detector

High-speed and high-accuracy mosaic detection node for ComfyUI. Supports FAST, ACCURATE, and HYBRID modes with ROI refinement.

By yano·Created 9 months ago·Updated 9 months ago· 3
yano/comfyui-fast-mosaic-detector
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Fast Mosaic Detector
fast-mosaic-detector
Readme

ComfyUI Fast Mosaic Detector

📘 English | 📗 日本語

High-precision & high-speed mosaic detection node for ComfyUI, featuring three modes (FAST / ACCURATE / HYBRID) and adaptive ROI refinement.
The HYBRID mode delivers near-ACCURATE precision at a fraction of the cost (7× faster).

🔍 Overview

This node detects mosaic (pixel-block censorship / block-pattern noise) from images or video frames.
It outputs:

  • A binary mask (0 or 255)
  • Estimated mosaic block size

The detector combines:

  • B-mode (FAST) — lightweight, CUDA batch-optimized
  • D-mode (ACCURATE) — full histogram + gradient + grid-structure analysis
  • HYBRID mode — FAST → ROI extraction → ACCURATE refinement

HYBRID mode typically achieves:

✅ ~85–95% of ACCURATE precision
✅ ~7× faster than ACCURATE
✅ Robust for video sequences

Workflow Screenshot

Workflow Screenshot

Input Video

https://github.com/user-attachments/assets/17b95590-77cc-435e-8df1-6cf04604c46b

example_input.mp4

Output Video (Image&Mask Blend)

https://github.com/user-attachments/assets/28731ee8-8a11-4971-af86-5be63b44a870

example_output.mp4

Example Workflow

See the example_workflow folder.

✅ Features

FAST Mode

  • ~4 sec for 840[frames]x640x480[pixels] @RTX3090 (210fps)
  • May over-detect
  • Best for quick estimation

ACCURATE Mode

  • ~420 sec for 840[frames]x640x480[pixels] @RTX3090 (0.5fps)
  • Best precision
  • Full-frame exhaustive scan

HYBRID Mode (Recommended)

  • ~40–60 sec for 840[frames]x640x480[pixels] @RTX3090 (14-21fps)
  • Near-accurate quality
  • Smart ROI refinement
  • Recommended for most use cases

✅ Inputs & Parameters

Below is the detailed explanation for every parameter in the node.

🖼 Image

image: IMAGE

Accepts single images or multi-frame batches.

🎛 ACCURATE Mode (D-mode) Parameters

✅ Skin Mask (HSV-based)

| Parameter | Description | |----------|-------------| | hsv_skin_h_low | Minimum hue for skin detection | | hsv_skin_h_high | Maximum hue | | hsv_skin_s_threshold | Minimum saturation |

Helps detect mosaics primarily appearing on skin regions.

✅ Gradient Detection

| Parameter | Description | |----------|-------------| | gradient_threshold | Threshold for edge gradient magnitude | | ratio_threshold | Gradient ratio threshold (block pattern strength) | | gradient_band_height | Height of sampling windows | | gradient_band_half_width | Half-width of sampling windows |

Controls how the algorithm identifies block-like structure.

✅ Histogram / Grid Structure

| Parameter | Description | |----------|-------------| | histogram_threshold | Required peak ratio of histogram bin | | mosaic_length_min | Minimum block size | | mosaic_length_max | Maximum block size | | intersection_margin | Allowed misalignment |

🚀 Execution Mode

mode: FAST | ACCURATE | HYBRID

  • FAST → Quick, lower precision
  • ACCURATE → Highest precision
  • HYBRID → Recommended balance

⚙ Backend Selection

processing_backend: AUTO | CPU | TORCH

  • AUTO → intelligently selects optimal mode
  • CPU → forces CPU
  • TORCH → forces PyTorch/CUDA

🔧 System Parameters

max_workers

CPU thread count for accurate mode.

Suggested: equal to physical CPU cores.

🟦 HYBRID Mode Parameters

fast_recall_boost

Boost recall of FAST detector (0.1–2.0).
Higher → more ROIs but may include noise.

roi_margin_px

Expand ROIs (recommended: 24px)

refine_logic

| Option | Meaning | |--------|---------| | replace | Replace FAST masks with refined results | | union | Merge masks | | intersect | Keep only overlapping |

Default: replace

ROI-related parameters

| Parameter | Description | |----------|-------------| | refine_frame_stride | Interval of refinement | | roi_merge_dilate_px | Unifies ROIs | | roi_max_count | ROI count limit | | min_mask_pixels | Minimum mask size | | frame_cover_threshold | Frame considered over-detected if exceeding ratio |

🟩 Adaptive ROI Downscaling

Automatically downscale large ROIs to accelerate refinement.

| Parameter | Description | |----------|-------------| | adaptive_roi_area_ratio | Shrink ROI when > this % of frame | | adaptive_roi_min_side | Small ROIs never downscale | | roi_downscale_large | Downscale rate (0.4–1.0) |

🟨 Aspect Ratio Filters

| Parameter | Description | |----------|-------------------------------------------------------| | roi_aspect_ratio_max | Ignore overly elongated ROIs (recommended range: 3-5) | | roi_min_short_side | Ignore too-small ROIs |

Useful for rejecting window frames, bars, non-mosaic patterns.

manifest.json

✅ Output

  • mask — 0/255 binary mosaic mask
  • size — detected mosaic block size

Fully batch-compatible with ComfyUI's image sequences.

✅ Recommended Presets

Best Practical

mode = HYBRID
roi_downscale_large = 0.75
roi_aspect_ratio_max = 3.0
fast_recall_boost = 0.9

Highest Precision

mode = ACCURATE

Fast Preview

mode = FAST

✅ Notes

  • Smaller mosaics require roi_downscale_large = 1.0

  • For anime/non-skin content → expand HSV ranges

  • If HYBRID misses regions → increase fast_recall_boost

  • This node is fully compatible with ComfyUI-VideoHelperSuite for loading video frames and saving processed video outputs. If you plan to use this node with video workflows, installing VideoHelperSuite is strongly recommended.

  • When processing Full HD video, we recommend downsizing the image to 0.5 to 0.75 times its original size, as this allows for sufficiently accurate estimation at a faster speed. Since the estimable mosaic size is approximately 4 to 30 pixels, we recommend resizing the image so that the mosaic fits within this size range.

✅ License

MIT

✅ Author

Takahiro Yano
ComfyUI Fast Mosaic Detector