JP2 to FITS Converter
Processing entirely on your device — large files may take a moment.
Convert FITS frames to PNG or JPG to preview telescope data, or pack them into a ZIP for sharing. If your files are still in JP2 format, this page is the shortcut: JPEG 2000 (JP2) is the wavelet-based successor of JPG — better detail at equal bitrate plus a true lossless mode, still standard in archives, medical imaging and Digital Cinema.
This converter runs entirely in your browser using WebAssembly — your files never leave your device, nothing is uploaded, and there are no watermarks, sign-ups or queues. Drop in several files at once to convert them as a batch.
How JP2 compares to FITS
| JP2 | FITS | |
|---|---|---|
| Compression | Wavelet (lossy + lossless) | None (optionally Rice/GZIP) |
| Transparency | Supported | Not supported |
| Animation | Not supported (MJ2 is separate) | Not supported |
| Metadata | XML boxes (EXIF/GPS) | Rich text header (WCS) |
| Best for | Archives, medical, cinema | Telescope frames, science data |
How to convert JP2 to FITS
- 1
Select your files
Drag & drop your JP2 files onto the area above, or click to browse. You can add multiple files at once for batch conversion.
- 2
Convert instantly
Click "Convert to FITS". The conversion runs entirely inside your browser using WebAssembly — no upload, no queue, no waiting.
- 3
Download results
Download each converted FITS file individually, or grab everything at once as a ZIP archive.
About the JP2 format
JPEG 2000 (JP2) replaced JPG's DCT blocks with wavelet transforms: at the same bitrate it shows fewer blocky artifacts, and its lossless mode compresses better than JPG ever could. It was the format of early digital cinema and remains common in archives, medical systems and geospatial pipelines.
Browser support never arrived — Chrome, Firefox and Safari all skip it — so a JP2 file is often invisible on the web. Converting JP2 to JPG or PNG makes archival material viewable anywhere; converting the other way gives long-term storage better compression.
+Strengths
- ✓True lossless mode
- ✓Better quality per byte than JPG
- ✓ROI / progressive decoding built in
!Limitations
- −No browser support
- −Slow to encode compared to JPG
About the FITS format
FITS (Flexible Image Transport System) has carried professional astronomy data since 1981: every file opens with a plain-text header that records telescope, instrument, exposure, filters and world coordinates, followed by raw pixel arrays — often 16-bit or float, sometimes data cubes.
Values can be negative or far above display range, so FITS never looks right in a photo viewer. Converting to PNG applies a simple scaling pass that reveals the nebula or galaxy in the numbers — good for previews, while science pipelines keep the original.
+Strengths
- ✓Self-documenting science headers
- ✓High bit depth (16/32-bit, float)
- ✓The standard of every observatory
!Limitations
- −Not display-ready
- −Files are large and uncompressed
Why convert JP2 to FITS?
Converting makes sense where the strengths of FITS meet what JP2 cannot give you. Self-documenting science headers Meanwhile No browser support One pass through the converter above puts your file on the right side of that trade-off.
Frequently asked questions
Is this JP2 to FITS converter really free?
Yes — completely free, with no sign-up, no watermark and no daily conversion limits. The site is supported by advertising.
Are my files uploaded to a server?
No. The conversion runs entirely inside your browser using WebAssembly, so your files never leave your device — that is what makes it instant and private.
Does it work on Windows, Mac, iPhone and Android?
Yes. Anything with a modern browser works: Windows, macOS, Linux, Android and iOS. No software installation is required.
Will I lose quality converting JP2 to FITS?
No — FITS is a lossless format, so every pixel of the converted image matches your original JP2 file. You can also adjust the quality/size balance before converting when the target format supports compression.
What happens to EXIF data and other metadata?
Conversions here re-encode the image, and re-encoding generally does not carry the original metadata over. If the EXIF data of your JP2 files matters (camera model, GPS, timestamps), keep the original file as the master and treat the converted copy as the shareable version.
Can I convert several JP2 files at once?
Yes — drop as many files as you like into the tool and they are converted in one batch. When more than one file comes out, everything is bundled into a ZIP for a single download.