FITS vs SVG
A detailed comparison of FITS Astronomical Image and SVG Vector 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 filesSVG Vector Image
Raster & Vector ImagesSVG is an XML-based vector image format that scales to any resolution without quality loss. It is the standard for web icons, logos, and illustrations that need to look sharp on all screen sizes.
About SVG 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.
SVG Strengths
- Resolution-independent — crisp at any size, from 16px icon to 4K billboard.
- Tiny file sizes for flat graphics, logos, and UI illustrations.
- Editable with any text editor; programmatically manipulable via DOM.
- Supports interactivity, CSS styling, and JavaScript inside the image.
- Accessible — text inside SVG is readable by screen readers.
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.
SVG Limitations
- Not suitable for photographs or complex raster imagery.
- Uploading user-provided SVG is risky — embedded scripts are an XSS vector.
- Complex SVGs with thousands of paths render more slowly than a PNG equivalent.
- Inconsistent rendering across browsers for edge-case features (filters, gradients).
- No native concept of layers or groups for design-tool round-tripping.
Technical Specifications
| Specification | FITS | SVG |
|---|---|---|
| MIME type | image/fits | image/svg+xml |
| 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 | — |
| Format | — | XML (text-based) |
| Current version | — | SVG 2 (W3C Recommendation, 2018) |
| Compression | — | Gzipped variant is .svgz |
| Resolution | — | Unlimited (vector) |
| Animation | — | SMIL, CSS, JavaScript |
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
SVG
- Simple icon 200 B – 2 KB
- Company logo 2–10 KB
- Complex illustration 20–100 KB
- Data-visualization chart 50–500 KB
Ready to convert?
Convert between FITS and SVG 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.
SVG (Scalable Vector Graphics) is an XML-based vector image format maintained by the W3C since 1999. Unlike raster formats, SVG images scale to any size without quality loss, making them perfect for responsive web design.
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.
SVG files open in all web browsers, Adobe Illustrator, Inkscape (free), Figma, and most modern design tools. You can also open SVGs with any text editor since they are XML-based.
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.