ComfyUI JXL Support

Load and save JPEG XL (.jxl) images in ComfyUI with lossy/lossless compression and optional workflow metadata compression.

Installation

open ComfyUI/custom_nodes/
git clone https://github.com/koloved/ComfyUI_jxl_support

Restart ComfyUI after installation.

Nodes

Save Image (JXL)

Input	Type	Default	Description
images	IMAGE	—	Batch of images to save
filename_prefix	STRING	ComfyUI	Output filename prefix
quality	INT (0–100)	100	100 = lossless; lower = smaller file
compress_metadata	BOOLEAN	True	Brotli-compress embedded workflow metadata

Load workflow from JXL Image

Reads embedded workflow metadata for drag-and-drop recovery.

Feature highlights

• Lossless at quality=100 — pixel-perfect output, ~40% smaller than PNG.
• Lossy at quality < 100
• Metadata compression toggle — disable compress_metadata to compare file size with uncompressed vs Brotli-compressed workflow metadata.
• Drag-and-drop restore — JS extension embeds workflow data for one-click recovery.

Size comparison (real-world example)

Format comparison (1024×1024 render)

Format	Size
PNG (lossless)	1.58 MB
JXL lossless (quality=100)	0.99 MB

Metadata compression impact (quality=40)

compress_metadata	File size
True (Brotli)	99 KB
False (raw JSON)	206 KB

Metadata compression is most noticeable on lossy files — workflow JSON can be 100+ of KB uncompressed.

Dependencies

Installed via requirements.txt:

Package	Purpose
imagecodecs	JXL encode / decode
brotli	Workflow metadata compression