FTS to SIX Converter

Get SIX output from your FTS data in seconds

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No Install Needed

The converter runs entirely in your browser — no desktop software required. Works on all major platforms and devices alike.

Batch Processing

Convert multiple FTS images to SIX in one session. Queue your images and let the converter process them all without manual repetition.

Visual Fidelity

Your FTS imagery is carefully converted to SIX with maximum quality retention. No unnecessary degradation during the transformation process.

How to convert FTS to SIX

1

Select files from Computer, Google Drive, Dropbox, URL or by dragging it on the page.

2

Choose six or any other format you need as a result (more than 200 formats supported)

3

Let the file convert and you can download your six file right afterwards

About formats

FTS is a file extension for the Flexible Image Transport System (FITS), the standard data format used in astronomy since 1981 when it was defined by Don Wells, Eric Greisen, and R.H. Harten at the National Radio Astronomy Observatory, and subsequently endorsed by the International Astronomical Union in 1982. FITS was designed from the outset as a self-describing archival format: each file begins with one or more 2880-byte header blocks containing ASCII keyword-value pairs that describe the data's dimensions, coordinate system, observation parameters, and provenance, followed by data blocks in a variety of numeric types — 8/16/32/64-bit integers and 32/64-bit IEEE floating-point values. FITS supports multi-dimensional arrays (images, data cubes, hypercubes), binary tables for catalog data, and ASCII tables, with multiple Header/Data Units (HDUs) that can coexist in a single file. The format handles specialized astronomical data: spectral cubes, radio interferometry visibilities, multi-extension mosaic images from CCD arrays, and time-series photometry. One advantage is scientific rigor: FITS mandates that all metadata needed to interpret the data physically — coordinate transformations (WCS), photometric calibration, telescope and instrument parameters — travels with the file, eliminating the metadata-loss problem that plagues general-purpose image formats in scientific contexts. The format's longevity and institutional backing is another strength — virtually every observatory, space telescope (Hubble, James Webb, Chandra), and astronomical software package (DS9, IRAF, Astropy) uses FITS as its primary data format.
Developer: NASA / IAU
Initial release: 1981
SIX is a file extension for SIXEL (Six Pixel) graphics data, a bitmap graphics format developed by Digital Equipment Corporation (DEC) in 1983 and introduced with the LA50 dot matrix printer. SIXEL encodes images as a sequence of printable ASCII characters, where each character represents a column of six vertical pixels (a 'sixel') — the character's ASCII value minus 63 provides a 6-bit binary pattern, with each bit controlling one pixel in the vertical column. The encoding is structured as a series of sixel bands (each six pixels tall) across the image width, with control sequences for color selection (up to 256 registers with HLS or RGB specification), repeat counts (run-length encoding for efficiency), carriage return, and newline commands. SIXEL data is transmitted to the output device using DEC's standard escape sequence protocol, embedded within the text stream alongside regular character output. Originally designed for DEC's line of printers and later supported by DEC VT-series terminals (VT240, VT330, VT340), SIXEL has experienced a remarkable revival in modern terminal emulator software. One advantage is terminal-native image display: SIXEL allows images to be rendered directly within a text terminal session without requiring a graphical window system, enabling command-line tools to display graphs, photographs, and previews inline with text output. This capability has driven adoption in modern terminals like mlterm, xterm, WezTerm, and foot. SIX/SIXEL data can be generated by ImageMagick, libsixel, and chafa, and viewed in any SIXEL-capable terminal emulator.
Initial release: 1983

Frequently Asked Questions

Why convert FTS to SIX?

SIX is widely supported across devices and applications — converting from FTS makes your astronomical images accessible to anyone without specialized tools.

What programs open SIX?

Any modern image viewer opens SIX — Windows Photos, macOS Preview, GIMP, Photoshop, and web browsers all support it.

Does this work on mobile devices?

Yes — the converter runs in any web browser, so it works on phones, tablets, laptops, and desktops regardless of operating system.

How long does the conversion take?

Most FTS to SIX conversions finish within seconds. Larger or more complex images may take slightly longer depending on the data size.

Does the conversion preserve quality?

The converter retains maximum fidelity during the FTS to SIX transformation. Any differences stem from the output format's own characteristics.

Is batch FTS to SIX conversion supported?

Absolutely — queue multiple FTS images and convert them all to SIX in a single session. No need to process one at a time.