Panel Colorization Comparison

Korean version

Date: 2026-05-22

This experiment checks whether OpenToonz-inspired preprocessing helps actual panel colorization on the local ComfyUI setup.

Input

Panel crops:

/Users/iwongyeong/AI/outputs/MC-13/split_v4/panels

Panels used:

panel_002.png
panel_003.png
panel_004.png
panel_005.png
panel_006.png

panel_001.png was excluded because it is mostly a page-label/text fragment.

Compared Inputs

For each panel, the comparison script generated:

source: resized raw blue rough crop.
clean_line: output from Blue Sketch Cleaner.
closed_line: Blue Sketch Cleaner plus Line Gap Closer.
region_preview: Color Region Finder preview for inspection only.
raw_color, clean_color, closed_color: colorization results from the selected ComfyUI workflow.

Workflows Tested

Qwen Image Edit

Qwen Image Edit was queued successfully, but local Apple Silicon MPS execution failed during sampling because the installed fp8mixed Qwen model requires a float8 path unsupported by MPS:

Trying to convert Float8_e4m3fn to the MPS backend but it does not have support for that dtype.

This path should be retried on a CUDA/NVIDIA machine.

SD1.5 Anything + Lineart ControlNet

Output:

outputs/color_compare_mc13_split_v4_controlnet_v3_same_seed

This workflow produced strong color, but it often reinterpreted the panel composition. Several raw or closed-line variants collapsed to black. It is not stable enough as the main research path.

SD1.5 Anything Img2Img

Output:

outputs/color_compare_mc13_split_v4_img2img

This workflow preserved composition better. Raw blue crops often kept blue artifacts, while clean_line and closed_line removed most blue signal. It still changed character identity and sometimes failed completely (panel_004).

Result

Best local path among tested options:

panel crop -> Blue Sketch Cleaner -> Line Gap Closer -> img2img colorization

However, this is not production-ready. The preprocessing is useful, but the available local SD1.5 colorization workflows are weaker than the line-prep nodes. The strongest next experiment is to rerun the same clean/closed panel inputs through Qwen Image Edit on CUDA, or another image-edit model that can preserve input composition better.

Key Takeaways

Panel crops are the correct input level for these nodes.
Blue Sketch Cleaner is helpful before colorization because raw blue lines tend to survive or steer the model badly.
Line Gap Closer sometimes helps, but it can also over-constrain or trigger unstable generations depending on the sampler seed.
Color Region Finder is useful as a fill-leak/debug preview, not as an automatic semantic palette.
Local MPS cannot run the current fp8 Qwen Image Edit model.

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