Better us of TIFF files, Astro-TIFF

[han59]

There is currently an initiative to make better use of the TIFF format for astronomy. The idea is to save a FITS header in a standard way into a TIFF file. This make conversion between TIFF and FITS possible without loosing header information.

The FITS header is stored in the description tag of the TIFF file. The specification is here:
http://www.hnsky.org/astro-tiff.htm


Benefits:

The TIFF compression algorithm makes the files smaller
The files are readable by almost any image viewer.

The proposal is to make SharpCap TIFF files compatible with this specification.

Han

[admin]

Hi,

interesting... right now, SharpCap writes to TIFF using OpenCV, which does not give any way to set extra info when writing the image - it's about as much as you can do to specify the compression mode.

I will have to look and see if I can find a .NET/C# library capable of opening the written image file and setting the tag as required.

cheers,

Robin

[han59]

Hi Robin,
I familiar with Pascal but not C#. But googling around I think libtiff can do it:

http://www.libtiff.org/index.html


The tag is:
ImageDescription and is covered by the library as described here:
http://www.libtiff.org/support.html
ImageDescription 270 R/W

It is is just a string/text of up to 64k you can fill with anything so also a header.

The only minor thing is LZW (5) compression not the later Deflate (8) Looking into opencv.org it seems relying on libtiff so the situation doesn't change.

Han

[admin]

Hi Han,

I found a thing called ExifLibNet that looks like it might do what I want - add Exif tags to an existing file. I need to test it. I will also check the compression, I think I am currently using deflate...

cheers,

Robin