The usual problem, not able to reproduce that from any of my 16 bit tiff images.
Can you give details of where you get the tiff files? Tiff has got so many different types and do you know the compression? If possible post an example (if not too large) on a file sharing site such as drop-box.
In Gimp 2.10.2 (Win10) you might get something like this https://i.imgur.com/NlD3Jhx.jpg but it opens as 16 bit.
A CMYK tiff does not open so the problem is not that.
Are you using the latest Gimp 2.10.2 for windows? The more information you give the better.
another answer simultaneously
The jpeg format is strictly 8 bit. That includes exporting a 16 bit image as a jpeg compressed tiff. There is a warning if you try that using Gimp. Like this https://i.imgur.com/phIGLVF.jpg
Ahh..re-read you are exporting the tiff as a jpeg. It will be 8 bit, quality is in the eye of the beholder. Just keep that as a finished product and use your 16 bit tiff for editing. In fact Gimp works better in 32 bit floating point so sometimes faster when you promote the bit depth.
Can you give details of where you get the tiff files? Tiff has got so many different types and do you know the compression? If possible post an example (if not too large) on a file sharing site such as drop-box.
In Gimp 2.10.2 (Win10) you might get something like this https://i.imgur.com/NlD3Jhx.jpg but it opens as 16 bit.
A CMYK tiff does not open so the problem is not that.
Are you using the latest Gimp 2.10.2 for windows? The more information you give the better.
another answer simultaneously
The jpeg format is strictly 8 bit. That includes exporting a 16 bit image as a jpeg compressed tiff. There is a warning if you try that using Gimp. Like this https://i.imgur.com/phIGLVF.jpg
Ahh..re-read you are exporting the tiff as a jpeg. It will be 8 bit, quality is in the eye of the beholder. Just keep that as a finished product and use your 16 bit tiff for editing. In fact Gimp works better in 32 bit floating point so sometimes faster when you promote the bit depth.