FITS vs WEBP
A detailed comparison of FITS Astronomical Image and WebP Image — file size, quality, compatibility, and which format to choose for your workflow.
Technical Specifications
| Specification | .FITS | .WEBP |
|---|---|---|
| MIME type | image/fits | image/webp |
| 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 | — | VP8 (lossy) or VP8L (lossless) |
| Color depth | — | 8 bits per channel |
| Max dimensions | — | 16,383 × 16,383 pixels |
| Transparency | — | Full 8-bit alpha channel |
| Animation | — | Supported since WebP 2012 revision |
Strengths 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.
.WEBP Strengths
- Smaller file sizes than JPEG, PNG, and GIF at equivalent visual quality.
- Single format for lossy photos, lossless graphics, transparency, and animation.
- Full alpha channel support with smaller files than PNG.
- Now universally supported in all modern browsers.
- Open-source reference implementation (libwebp) by Google.
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.
.WEBP — Limitations
- Some older software and image editors still don't read WebP natively.
- Max dimensions are 16,383 × 16,383 — lower than JPEG or PNG.
- Print workflows rarely support WebP (no CMYK, limited color management).
- Editing tools are less mature than JPEG/PNG; round-tripping can lose quality.
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.
WebP is a modern image format developed by Google in 2010. It supports both lossy and lossless compression, transparency, and animation, while delivering files 25-35% smaller than JPEG and PNG equivalents.
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.
WebP files open natively in Chrome, Firefox, Safari, Edge, and most modern image viewers. On Windows, the Photos app supports WebP. On macOS, Preview handles it from macOS Big Sur onward.
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.
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