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Image2JXL — Lossless JPEG to JPEG XL Conversion on Mac

· 5 min read
Image2JXL
JPEG XL Converter
HP60
HP60Apps

Image2JXL is a native macOS app for local JPEG XL conversion, with a focus on JPG to JXL workflows. For JPEG input, it supports reversible JPEG transcoding, so a supported JPG can be stored as a JXL file and restored back to JPG later.

It is useful if you want a local tool for batch organization, archive workflows, and testing JPEG XL without uploading files or relying on a cloud converter.

Image2JXL app icon

JPG to JPEG XL, With Reversible JPEG Transcoding​

JPG remains one of the most common image formats. Image2JXL is built for people who want to try a JPEG XL workflow on Mac without sending files through an online converter.

For JPEG input, Image2JXL can use JPEG XL's reversible JPEG transcoding path. That means a supported JPG can be stored as a JXL file while keeping a workflow that can restore it back to JPG later.

This is different from simply decoding the JPG pixels and saving them again. Reversible JPEG transcoding is intended for JPEG files specifically. Other supported image inputs may use pixel-based JPEG XL encoding, but that does not promise byte-for-byte restoration of the original file container.

A Small Lossless JPEG Test​

Here is one concrete test with Image2JXL:

  • Original file: DSCN0010.jpg, 162 KB
  • After lossless JPEG-to-JXL conversion: DSCN0010.jxl, 131 KB
  • After restoring the JXL back to JPG, the restored JPG had the same SHA-256 hash as the original file:
17307b1207eb6487d7908e9d154890b46e3d2e0192369cfd3f4c33d5a5af4035

In this case, JPEG XL reduced the storage size while still allowing the original JPG codestream to be reconstructed exactly when needed. This is an example of the reversible JPEG path, not a promise that every image or every source format will produce the same size reduction.

What Image2JXL Does​

Image2JXL focuses on JPEG XL workflows on macOS. The core tasks are straightforward:

  • Convert supported image formats to JPEG XL.
  • Export JPEG XL files to JPEG, PNG, or GIF.
  • Convert files and folders in batches.
  • Review per-file conversion status.
  • Choose output behavior, including saving beside the source or choosing another destination.
  • Preserve supported EXIF and XMP metadata when the selected conversion path supports it.

The app is designed for local file conversion rather than a browser-based or cloud conversion flow.

Convert Images to JPEG XL​

Image2JXL can convert JPEG, PNG/APNG, GIF, TIFF, BMP, EXR, NetPBM, and PFM inputs to JPEG XL through its current conversion pipeline.

For JPEG input, the app can use lossless JPEG transcoding. This is useful when you want to store JPG images in JPEG XL while keeping a reversible JPEG workflow where supported.

For other supported inputs, Image2JXL can create JPEG XL output using the app's available quality, distance, and effort controls. These settings are useful when preparing image collections for storage, testing JPEG XL output, or keeping a consistent conversion setup across many files.

Export JPEG XL Files​

Image2JXL can also export JXL files back to JPEG, PNG, or GIF. This helps when you need to share or reuse files in software that does not accept JPEG XL.

Common export scenarios include:

  • Turning a JXL file into JPEG for broad compatibility.
  • Exporting to PNG when a lossless raster format is preferred.
  • Exporting animation-oriented JXL content to GIF when that target fits the workflow.

The app also includes fallback behavior for JXL-to-JPEG export when lossless JPEG reconstruction is unavailable, so the conversion result can still be saved as a normal JPEG with a clear note.

Batch and Folder Workflows​

Image2JXL supports importing individual files and folders. You can drag files or folders into the app, run a batch conversion, and check the status of each item.

This is helpful for:

  • Importing a folder of JPG files and converting them locally.
  • Converting a folder of website or app assets to JPEG XL.
  • Preparing a set of reference images for storage.
  • Testing JPEG XL output across multiple source formats.
  • Exporting a collection of JXL files back to compatibility formats.

Pro workflow helpers include preserving folder structure and moving originals to Trash after successful conversion.

Metadata and Output Controls​

Image2JXL can preserve supported EXIF and XMP metadata when the target workflow supports it. This applies to supported paths such as image-to-JPEG XL, JPEG XL-to-JPEG, and JPEG XL-to-PNG. GIF export does not promise metadata preservation.

The app also provides output controls for different working styles:

  • Save converted files beside the source.
  • Choose an output folder.
  • Ask before saving.
  • Preserve folder structure with Pro.

These options are especially useful when converting folders because they reduce manual file organization after the conversion finishes.

When Image2JXL Is Useful​

Image2JXL is a good fit when you specifically need a Mac app for JPEG XL conversion and want the files processed locally.

Typical use cases include:

  • Archiving JPEG collections into JPEG XL with a reversible JPEG workflow where supported.
  • Organizing batches of JPG images into JXL files while keeping a restore-to-JPG path where supported.
  • Trying JPEG XL on a native macOS app before changing a larger image workflow.
  • Converting image folders to JXL for storage or testing.
  • Exporting JXL files to JPEG, PNG, or GIF for compatibility with other apps.
  • Running repeatable batch conversions without uploading source files.
  • Keeping source folders and converted output organized during a larger image workflow.

Image2JXL is not intended to be a general converter for every image format. The current import pipeline does not accept WebP, AVIF, HEIC/HEIF, TGA, PSD, RAW, SVG, PDF, or ICO as image-to-JPEG XL inputs.

Get Image2JXL​

Image2JXL is available on the Mac App Store for macOS.

Download Image2JXL on the Mac App Store