FITS vs PNG
A detailed comparison of FITS Astronomical Image and PNG 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 filesPNG Image
Raster & Vector ImagesPNG is a lossless image format that supports transparency. It is ideal for graphics, logos, screenshots, and any image where preserving exact pixel data is important.
About PNG 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.
PNG Strengths
- Lossless compression — every save preserves the original pixels perfectly.
- Full 8-bit alpha channel for smooth transparency.
- Excellent for text, UI screenshots, logos, and line art.
- Royalty-free and an ISO standard (ISO/IEC 15948).
- Supports 16-bit color depth for high-fidelity work.
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.
PNG Limitations
- Much larger than JPEG for photographs (no perceptual compression).
- No native animation in most software (APNG support is inconsistent).
- No CMYK support — web and screen only, not print.
- Metadata capabilities are less rich than JPEG's EXIF.
Technical Specifications
| Specification | FITS | PNG |
|---|---|---|
| MIME type | image/fits | image/png |
| Extensions | .fits, .fit, .fts | — |
| Standard | IAU-endorsed FITS 4.0 (latest revision) | ISO/IEC 15948:2004 |
| Header records | 80-character ASCII cards | — |
| Encoding | IEEE big-endian integers and floats | — |
| Compression | — | Lossless — DEFLATE (zlib) |
| Color depth | — | 1, 2, 4, 8 or 16 bits per channel |
| Max dimensions | — | 2^31 − 1 pixels per side (2.1 billion) |
| Transparency | — | Full 8-bit alpha channel |
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
PNG
- Icon or small logo 2–20 KB
- UI screenshot (1920×1080) 200–800 KB
- High-res photo (12 MP) 10–30 MB
- Print-ready illustration 5–50 MB
Ready to convert?
Convert between FITS and PNG 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.
PNG (Portable Network Graphics) is a lossless raster image format created in 1996 as a patent-free alternative to GIF. It supports transparency, making it ideal for logos, icons, and web graphics.
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.
PNG files open natively in all modern operating systems, web browsers, and image editors including Photoshop, GIMP, Paint.NET, and Canva.
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.