How to Convert Multiple JXL Images to FITS?
1. Download and Install reaConverter
reaConverter installs quickly on any Windows PC. No dependencies, no bloatware — just a clean setup that's ready to use immediately. You can also resize, crop, and adjust images during conversion.
2. Load your JXL files
Launch reaConverter and load the JXL files you want to convert. Add a few files or thousands, batch processing handles them all.
Drag-and-drop JXLs directly into reaConverter or use the folder browser to load entire directories.
3. Select FITS as output format
Set FITS as output format and select where to save your converted files. Customize quality settings if needed.
4. Start JXL to FITS conversion
Press Convert to begin processing. You can watch the progress or minimize and let it run in the background.
Your converted FITS files will appear in the destination folder as soon as processing completes.
How JXL and FITS differ in practice
JXL can carry an alpha channel and FITS cannot. Transparent areas are composited onto a solid background during conversion, so pick that background colour deliberately: white is the default, and it is rarely the right choice for a logo that will sit on a dark page. FITS is lossless, so nothing further is discarded during conversion. What it cannot do is restore detail that JXL compression already removed, and the output file will usually be considerably larger.
