FITS to PDF
Turn a FITS astronomy image into a one-page grayscale PDF. Pixel values are stretched linearly for display, so the PDF is for viewing, not measurement.
Format Comparison & Technical Specifications
| Specification | FITS | |
|---|---|---|
| MIME Type | application/fits | application/pdf |
| Type | astronomical data container | document container |
| Compression | uncompressed / tile-compressed (fpack) | Flate / JPEG / JBIG2 / CCITT |
| Standard Specification | IAU FITS Standard 4.0 | ISO 32000-2:2020 |
| Magic Bytes Header | 53 49 4D 50 4C 45 20 20 3D 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 20 54 (SIMPLE = T) | 25 50 44 46 (%PDF) |
Format Overview & Applications
Astronomers can attach a visually stretched image to observing notes, but quantitative analysis belongs with the FITS array and its coordinate headers.
Technical Specifications & Codec Breakdown
The FITS reader selects the first primary or IMAGE-extension HDU with at least two axes, applies BSCALE/BZERO, normalizes that plane’s finite min-to-max range, and rounds it to 8-bit grayscale.
OS & Browser Compatibility
Astronomy software such as DS9 or Astropy can inspect FITS arrays and headers; a PDF reader can show the stretched preview beside a paper draft but cannot query its pixel values.
Useful info
Choose the stretch you want in an astronomy tool before conversion if you need a publication-ready view; this path applies a simple linear min/max stretch to the selected plane.
Format Comparison & Technical Specifications
A 2048×2048 FITS observation plane becomes a 13.7×13.7 inch grayscale figure at 150 dpi.
Frequently Asked Questions
Which FITS HDU is rendered?
The first HDU that is a primary image or IMAGE extension and has at least two axes is selected; the converter reads its first width-by-height plane.
Does the PDF preserve quantitative intensity values?
Finite values are scaled across that plane’s minimum and maximum into 256 grayscale levels, so the PDF is for viewing rather than measurement.