FR: report Roll Angle

[trougnouf]

Modern cameras have a digital meter which should be used to store the angle in EXIF data. This data could be used by development software to auto-rotate the pictures (eg this FR: darktable-org/darktable#6423 )

Can the Roll Angle be added to the tags reported by exiv2 ? This would be the first step to implement such a feature in darktable.

It is shown by exiftool for some cameras such as the Nikon D850 and D500 (samples on https://raw.pixls.us/#repo ), and documented in https://exiftool.org/TagNames/Pentax.html and https://exiftool.org/TagNames/Nikon.html

I am trying to extract the tag information from my Fujifilm X-T1 and soon in a Nikon Z6

[clanmills]

I'll investigate this. It's probably stored in the MakerNote and can be added. Can you:

1. Find the URL of an image that contains the data.
2. Use exiftool to show me the data you'll like Exiv2 to reveal.

[trougnouf]

Thank you @clanmills ! Below are a few samples:

https://raw.pixls.us/getfile.php/1835/nice/Nikon%20-%20D850%20-%2012bit%20compressed%20(Lossless)%20(3:2).NEF
Roll Angle : 0.5

https://raw.pixls.us/getfile.php/2504/nice/Nikon%20-%20D500%20-%2012bit%20compressed%20(Lossy%20(type%202))%20(3:2).NEF
Roll Angle : -1.8

https://raw.pixls.us/getfile.php/830/nice/Pentax%20-%20K-x%20-%2012bit%20(3:2).DNG
https://raw.pixls.us/getfile.php/830/nice/Pentax%20-%20K-x%20-%2012bit%20(3:2).PEF
Roll Angle : -45

https://raw.pixls.us/getfile.php/828/nice/Pentax%20-%20K-7%20-%2012bit%20(3:2).PEF
Roll Angle : 0