Convert ISS to FITS

Need to convert hundreds of ISS files to FITS? reaConverter does it in one click. No file limits, no watermarks, no internet required.

Need to convert ISS to FITS? reaConverter handles batch conversion with ease, processing hundreds of files at once while preserving quality. Your files never leave your machine. No third-party servers, no privacy concerns.

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ISS to FITS
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How to Convert Multiple ISS Files to FITS?

1. Download and Install reaConverter

reaConverter is a standalone Windows app — download, install, and start converting ISS files in under two minutes.

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Install reaConverter

2. Load your ISS files

Launch reaConverter and load the ISS files you want to convert. Add a few files or thousands, batch processing handles them all.

Drag-and-drop ISSs directly into reaConverter or use the folder browser to load entire directories.

Load your ISS files into reaConverter

3. Select FITS as output format

Set FITS as output format and select where to save your converted files. Customize quality settings if needed.

Select FITS as output format

4. Start ISS to FITS conversion

Press Convert to begin processing. You can watch the progress or minimize and let it run in the background.

Start Conversion

Your converted FITS files will appear in the destination folder as soon as processing completes.

ISS to FITS Converter

reaConverter offers the fastest, simplest solution for converting your ISS files into FITS in seconds - all files processed on your PC for maximum privacy and speed.

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Do more with your files

Converting ISS files for use in a workflow? reaConverter offers many ways to process files, so you can customize them according to your requirements.

Our range of editing options includes auto-processing options such as auto-rotate, auto-crop, watermarking and more. Change Color Space, copy Metadata, set DPI, manage ICC Profile, control Bit Depth.

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Image editing

User Reviews

Average User Rating:
Last updated on January 25, 2026
"reaConverter makes FITS conversion incredibly easy. We batch convert astronomical images to standard formats for presentations and analysis, all automated through the command-line. It’s fast, reliable, and handles large datasets without issues."
Laura N.
Laura N.
Astrophysics Research Assistant
"Essential for our astroimaging pipeline! reaConverter perfectly handles FITS files from our research telescope, preserving all WCS coordinates and photometric data during batch conversion to TIFF. Now we process 100+ deep-sky exposures nightly without losing critical metadata for our exoplanet studies!"
Joseph Wilson
Joseph Wilson
Satisfied Customer
"An efficient all-in-one solution for image conversion and light editing, designed for maximum user-friendliness."
Elena Anderson
Elena Anderson
Happy User
"Enable shell integration for lightning-fast file conversions directly from Windows Explorer."
R. Lewis
R. Lewis
Happy User
"After 200+ conversions on my budget laptop (i3-1115G4/4GB RAM/Win11), reaConverter outperforms heavyweight tools. Zero crashes, low CPU usage during batch processing, and no internet dependency - exactly what professionals need."
Walter Morgan
Walter Morgan
Satisfied Customer
"Your solution was buried deeper in search results than it should be. After struggling with unclear alternatives, I found your guides — finally, instructions that made sense for a first-time user like me. Excellent work!"
Richard E. Miller
Richard E. Miller
Satisfied Customer

ISS to FITS Conversion: FAQ

What are ISS files?

The ISS image format is considered rare and obsolete, and such files can only be opened using a limited number of image viewers. ISS files most likely contain bitmap images that were created or edited a long time ago. In case you have received such a file or found one on an old hard-drive, the best way to access its content is conversion to a better known format, such as JPEG or PNG.

What are FITS files?

The FITS (Flexible Image Transport System) format is a standard format used particularly for storing, transferring and processing scientific images from fields such as astronomy. FITS was first launched as an open standard in the early 1980s and has gone through several subsequent upgrades. FITS files contain not just images, but also data related to photometry and spatial calibration, and information about the origin of the image. Similar formats include FIT and FTS.

Can reaConverter convert ISS to FITS?

Yes! reaConverter instantly converts .iss to .fits with perfect quality preservation. With its batch processing feature, you can convert multiple files at once in just a few clicks. You can even convert images directly from Windows Explorer using the right-click menu — fast and convenient.

Can I convert ISS to FITS online?

If you only need to convert a few ISS files to FITS format, feel free to try our free online free online ISS to FITS converter — perfect for small batches with no installation needed!

How can I turn ISS files into FITS on my computer?

The best way to change ISSs to FITSs on your PC is to install a quality piece of software, such as reaConverter. This software is extremely efficient in managing a wide range of batch files conversions, including conversion from ISS to FITS.

How can I automate ISS to FITS files conversion?

reaConverter supports all the most useful automation features such as right-click сonversion and Watch Folders for the most efficient automated files conversion in any software of this type.

Is there a way to convert ISS files to FITS using the command prompt?

reaConverter provides full access to all its features via Windows command line, including a high-performance command-line iss to fits converter for batch processing.

What else can I do with reaConverter?

Convert GIS filesConvert Gerber imagesCrop photosConvert PDFAdd watermark on photo

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