XPM to FITS Converter
Processing entirely on your device — large files may take a moment.
X11 Pixmap and Flexible Image Transport System exist for different jobs: XPM (X11 Pixmap) is an image written as C source code — plain ASCII text that compilers and editors ingest directly, the classic icon format of Linux desktops and legacy X11 apps. Convert FITS frames to PNG or JPG to preview telescope data, or pack them into a ZIP for sharing.
This converter runs entirely in your browser using WebAssembly — your files never leave your device, nothing is uploaded, and there are no watermarks, sign-ups or queues. Drop in several files at once to convert them as a batch.
How XPM compares to FITS
| XPM | FITS | |
|---|---|---|
| Compression | None (ASCII text) | None (optionally Rice/GZIP) |
| Transparency | Single transparent color | Not supported |
| Animation | Not supported | Not supported |
| Metadata | Not supported | Rich text header (WCS) |
| Best for | Linux icons, X11 themes | Telescope frames, science data |
How to convert XPM to FITS
- 1
Select your files
Drag & drop your XPM files onto the area above, or click to browse. You can add multiple files at once for batch conversion.
- 2
Convert instantly
Click "Convert to FITS". The conversion runs entirely inside your browser using WebAssembly — no upload, no queue, no waiting.
- 3
Download results
Download each converted FITS file individually, or grab everything at once as a ZIP archive.
About the XPM format
XPM (X11 Pixmap) is an image format that is literally C source code: pixels are listed as character-to-color mappings inside an ASCII array. Compilers, text editors and version control all treat it as plain text, which is why Linux desktop icons and legacy X11 application assets have used it for decades.
XPM is limited to 256 colors per image and stores no alpha beyond a designated transparent character, so it is a niche target: mainly icon themes, window-manager decorations and retro programming projects.
+Strengths
- ✓Plain text — diffs and greps
- ✓Compiles straight into C programs
- ✓Tiny for small flat icons
!Limitations
- −256 colors maximum
- −Poor alpha (one transparent color)
About the FITS format
FITS (Flexible Image Transport System) has carried professional astronomy data since 1981: every file opens with a plain-text header that records telescope, instrument, exposure, filters and world coordinates, followed by raw pixel arrays — often 16-bit or float, sometimes data cubes.
Values can be negative or far above display range, so FITS never looks right in a photo viewer. Converting to PNG applies a simple scaling pass that reveals the nebula or galaxy in the numbers — good for previews, while science pipelines keep the original.
+Strengths
- ✓Self-documenting science headers
- ✓High bit depth (16/32-bit, float)
- ✓The standard of every observatory
!Limitations
- −Not display-ready
- −Files are large and uncompressed
Why convert XPM to FITS?
Think of it as moving your file to the container that fits the job. 256 colors maximum FITS works differently: Self-documenting science headers If any of that sounds like your task, run the conversion — it takes seconds and nothing leaves your device.
Frequently asked questions
Is this XPM to FITS converter really free?
Yes — completely free, with no sign-up, no watermark and no daily conversion limits. The site is supported by advertising.
Are my files uploaded to a server?
No. The conversion runs entirely inside your browser using WebAssembly, so your files never leave your device — that is what makes it instant and private.
Does it work on Windows, Mac, iPhone and Android?
Yes. Anything with a modern browser works: Windows, macOS, Linux, Android and iOS. No software installation is required.
Will I lose quality converting XPM to FITS?
No — FITS is a lossless format, so every pixel of the converted image matches your original XPM file. You can also adjust the quality/size balance before converting when the target format supports compression.
Can I convert several XPM files at once?
Yes — drop as many files as you like into the tool and they are converted in one batch. When more than one file comes out, everything is bundled into a ZIP for a single download.
Will transparent areas survive the conversion to FITS?
Transparency is kept whenever FITS actually supports an alpha channel. If the target format has none (like JPG), transparent areas are flattened onto a white background — that is a property of the format, not of this tool.