4 replies to this topic

[n00btastic]

I'm trying to learn Siril to stack and process my Canon R8 images, using 1.4 Beta 2's convert option to turn the .cr3 images into fits files first. When I run exitfool 12.40 on the source and destination files, I see I lose lots and lots of metadata that I'd like to preserve  (e.g. camera temperature) in the destination file.

 

Looking through the Siril docs, I don't see any options that seem relevant. Am I overlooking something? Is this a limitation of the fits file format? Or, is there another .cr3 -> .fit tool I should be looking at that will preserve all the metadata with conversion? I have a preference for Linux-based tools, but if the best options are Mac or Windows, I'd love to hear about them too. Thanks.

[prookyon]

FITS file format was never designed with the intent of supporting EXIF metadata.

As far as I know EXIF is largely not even standardized (a lot of the fields are manufacturer specific, not officially documented at all and tools like exiftool have just reverse-engineered their meaning).

To be fair FITS has kind of the same issue with various hardware / software living in their own bubble.

So even if some obscure tool has a way of stuffing it all into FITS - it might be the only tool that also can show/extract it properly afterwards.

[n00btastic]

Hi, thanks for the reply. FITS does support non-reserved key/value pairs in its header (though with some length limits). I tested this out by using astropy to write an arbitrary key-value pair into a Siril-created .fit file. Siril 1.4B2 does show this data (open .fit file, right click, FITS header...) , and so does exiftool. So I do not think inter-application compatibility is much of an issue here.

 

But back to the original question, anyone know of a .cr3 -> .fit tool on any OS that preserves all the source metadata? Trying to avoid writing the Siril wrapper script to do this if I can.

[prookyon]

If you don't happen to find anything then maybe just dumping the exiftool output to sidecar text files or one concatenated file per folder? Assuming this is mostly for future reference.

[lock042]

Siril (and other software) uses libraw to read RAW files. However, many EXIF metadata are not supported. This is particularly true of metadata written in XMP blocks.