https://github.com/ilia-kosenkov/fits-cs

IO library for FITS files
https://github.com/ilia-kosenkov/fits-cs

Last synced: 19 days ago
JSON representation

IO library for FITS files

• Host: GitHub
• URL: https://github.com/ilia-kosenkov/fits-cs
• Owner: Ilia-Kosenkov
• License: mit
• Created: 2019-09-25T21:05:54.000Z (about 5 years ago)
• Default Branch: master
• Last Pushed: 2021-04-27T20:22:12.000Z (over 3 years ago)
• Last Synced: 2024-10-07T08:10:10.810Z (about 1 month ago)
• Language: C#
• Homepage:
• Size: 579 KB
• Stars: 1
• Watchers: 2
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

Awesome Lists containing this project

README

        
# Fits-Cs

`Fits-Cs` is an attempt to bring [`FITS`](https://fits.gsfc.nasa.gov/) support to `.NET` environment. 

Currently, `NASA` [lists](https://fits.gsfc.nasa.gov/fits_libraries.html) only two `.NET` libraries written in `C#`, one of which is apparently unavailable, another - was updated [in 2003](http://skyservice.pha.jhu.edu/develop/Fitslib/).

In the era of `.NET Core`, there should be a better parsing option.

## What this project is about?

This library is an updated version of the custom `FITS` IO lib that is used with the `DIPOL-UF` optical polarimeter. While polarimeter requires only basic support of (uncompressed) single-unit (i.e. no extensions) image support, it is good to have universal tool (or at least as flexible as possible) to deal with `FITS`.

While `FITS` [standard](https://fits.gsfc.nasa.gov/fits_standard.html) is quite complicated, the majority of the features are intended to be supported.

## The concept

`Fits-Cs` is built around `FitsReader`/`FitsWriter` classes, which mimic the role of `System.IO.StreamReader/StreamWriter`.

The stream is read as a sequence of 2880-bytes [**blobs**](Fits-Cs/DataBlob.cs), and a valid sequence of blobs can be converted into a [**data block**](Fits-Cs/Block.cs), which stores header key collection, information about the data types and size of the data array and a buffer containing all the data corresponding to this unit. Another library will be used to parse this segmented data blocks into images/tables/other formats.

To send data to a stream, it should be first converted to correct **data blocks**, which represent one valid `FITS` unit, which are then written as as sequence of 2880-bytes blobs.

## An example

```cs

// Assuming suport of C# 8.0

static async Task Example()

{

    var path = "path-to-some-fits.fits";

    using var fStr = new FileStream(path, FileMode.Open, FileAccess.Read);

    await using var fitsReader = new FitsReader(fStr);

    await foreach (var block in fitsReader.EnumerateBlocksAsync())

    {

        // block is a valid FITS unit, and reader enumerates through 

        // all valid units in the file

        foreach (var key in block.Keys)

            // Prints formatted key data with a data-type prefix

            // key in collection can be null only if parsing fails, 

            // which happens only if it does not conform to the standard

            Console.WriteLine(key?.ToString(true));

    }

}

```

To test the library, a set of *default* `FITS` [files](https://fits.gsfc.nasa.gov/fits_samples.html) provided by `NASA` is used. 

The goal is to be able to reasonable parse everything presented there, including 64-bit integers in main data array and keywords (implemented) and `CONTINUE` special keyword-extension to regular strings (halfway there). No support for non-standard characters in key names is planned.