| name | from-jxl |
| description | Decode JPEG XL images (.jxl) to PNG or JPEG. Use when you need to convert JXL files back to standard formats for compatibility, display, or further editing. |
| disable-model-invocation | false |
| allowed-tools | Bash(djxl *), Bash(ls *), Bash(find *), Bash(mkdir *), Bash(rm *), Read, Write |
Decode JPEG XL Images
Extract images from JPEG XL (.jxl) files using djxl. Outputs PNG or JPEG, with optional recovery of original JPEG bitstream if the source JXL was a lossless JPEG transcode.
When to use
- Converting JXL files back to PNG for general use or compatibility.
- Recovering the original JPEG bitstream from a lossless-transcoded JXL file via
djxl --jpeg.
- Batch-decoding a JXL archive to portable formats.
Inputs to gather
- Input .jxl file or directory — single file or folder.
- Output format —
png (default) or jpeg. If the user has a JXL that came from a lossless JPEG transcode and wants to recover the original JPEG byte-exact, offer the jpeg format and explain the --jpeg flag.
- Output directory — optional. Default: same directory as input.
Procedure
1. Check tooling
command -v djxl || echo "djxl not installed — install with: sudo apt install libjxl-tools"
Abort if missing.
2. Determine scope and format
- Single file: direct conversion.
- Directory (non-recursive): loop over all
.jxl files.
- Recursive: use
find to locate .jxl files in the tree.
Confirm the output format with the user.
3. Decode
Single file to PNG (default):
djxl input.jxl output.png
Single file to JPEG (standard):
djxl input.jxl output.jpg
Single file to original JPEG (lossless transcode recovery):
If the JXL was created via cjxl in.jpg out.jxl, this recovers the original JPEG bitstream byte-exact:
djxl --jpeg input.jxl recovered.jpg
Batch (folder or recursive):
find <target> -maxdepth <1|999> -type f -iname '*.jxl' \
-exec djxl {} {.}.<format> \;
(Replace <format> with png or jpg, or —jpeg flag for JPEG recovery.)
4. Report
After decoding:
- Count of files decoded, skipped, failed.
- Output file sizes and locations.
- If batch, show a summary of converted files.
Output / side effects
- New PNG or JPEG files created in the output directory.
- Original
.jxl files remain unchanged.
Notes
- Lossless JPEG recovery: Only use
djxl --jpeg if you are confident the .jxl source was created via lossless JPEG transcode (i.e., cjxl original.jpg encoded.jxl). For JXL files created from PNG or other sources, --jpeg may produce incorrect results.
- Alpha channels: JXL alpha is preserved when decoding to PNG. JPEG does not support transparency, so any alpha will be lost if decoding to JPEG.
- Color profile: JXL can carry ICC color profiles;
djxl preserves them in the output.
- Depends:
apt install libjxl-tools.
