FITS vs GIF
A detailed comparison of FITS Astronomical Image and GIF Image — file size, quality, compatibility, and which format to choose for your workflow.
FITS Astronomical Image
Raster & Vector ImagesFITS (Flexible Image Transport System) is the standard digital file format in astronomy for storing images, tables, and metadata from telescopes and satellites. It supports multi-dimensional arrays and extensive header metadata for scientific observation records.
About FITS filesGIF Image
Raster & Vector ImagesGIF supports animation and transparency with a 256-color palette. While limited in color depth, it remains the most universally supported animated image format across platforms and messaging apps.
About GIF filesStrengths Comparison
FITS Strengths
- Self-documenting — every file carries complete observational metadata.
- Lossless — bit-exact storage of detector readouts.
- Stable since 1981 with zero breaking changes.
- Mandatory for professional astronomy — every research publication uses it.
- Open standard endorsed by IAU.
GIF Strengths
- Universal animation support — every browser, every chat app, every social network.
- Transparent backgrounds for compositing against any page color.
- Lossless for its limited palette — pixel-perfect at 256 colors.
- Self-contained: no codec, no browser plugin, no third-party player needed.
Limitations
FITS Limitations
- Niche — used almost exclusively in astronomy.
- File sizes are large (no default compression).
- Not a display format outside specialized viewers (DS9, AstroBin).
- Consumer imaging apps don't understand FITS.
GIF Limitations
- Limited to 256 colors per frame — looks posterized on photographs.
- Dithering for color-rich images makes files huge (often 10× an MP4 equivalent).
- No audio track.
- Transparency is 1-bit (on/off) — no smooth alpha blending.
- Poor compression compared to modern formats (WebP, MP4, AVIF).
Technical Specifications
| Specification | FITS | GIF |
|---|---|---|
| MIME type | image/fits | image/gif |
| Extensions | .fits, .fit, .fts | — |
| Standard | IAU-endorsed FITS 4.0 (latest revision) | — |
| Header records | 80-character ASCII cards | — |
| Encoding | IEEE big-endian integers and floats | — |
| Compression | — | LZW (lossless, patent expired 2004) |
| Color depth | — | 8-bit indexed (256 colors per frame) |
| Transparency | — | 1-bit (on/off) |
| Animation | — | Supported natively |
| Max dimensions | — | 65,535 × 65,535 per frame |
Typical File Sizes
FITS
- Backyard-telescope CCD shot (5 MP) 10-30 MB
- Hubble WFC3 single exposure ~65 MB
- JWST NIRCam full detector ~650 MB
GIF
- Short reaction meme (2s loop) 500 KB – 2 MB
- Screen recording demo (10s) 3–15 MB
- Static transparent icon 2–20 KB
Ready to convert?
Convert between FITS and GIF online, free, and without installing anything. Encrypted upload, automatic deletion after 2 hours.
Frequently Asked Questions
FITS (FITS Astronomical Image) is an image format used to store raster graphics — a two-dimensional grid of pixels describing a picture. It is part of the raster & vector images family and designed around a specific trade-off between file size, visual fidelity, and feature support (transparency, colour depth, compression type). Photographers, web designers, and content creators choose FITS when its particular strengths match the publishing target.
GIF (Graphics Interchange Format) was created by CompuServe in 1987. It supports animation and transparency but is limited to 256 colors per frame. It became the de facto format for short animated loops on the web.
Most desktop photo viewers (Windows Photos, macOS Preview, GIMP, Photoshop, Affinity Photo) open FITS natively. On mobile, iOS Photos and Google Photos display FITS in the gallery when supported by the OS. If the format is rare or new, convert to JPG or PNG first — both are universally readable — using our FITS to JPG or FITS to PNG converter.
GIF files open in all web browsers, image viewers, and messaging apps. For animated GIFs, use a web browser or media player like VLC. Static GIF images open in any image editor.
Upload the FITS to KaijuConverter and pick a target format (JPG, PNG, WebP, HEIC, TIFF, BMP, SVG, PDF). The conversion runs in the browser via ImageMagick and returns a download in seconds. No account or installation required; both input and output delete automatically within two hours.
It depends on the task. JPG is the smallest file size for photographs; PNG is lossless with transparency; FITS has its own niche that may favour colour depth, animation, or encoding efficiency over one or both of those. For the final web publish, test all three and measure file size plus visible quality on real content.