Is it possible to compress 48-bit TIFFs?

[DrFrag]

I have some uncompressed 48-bit TIFFs I'm storing at maximum quality for archival purposes, and I'd like to use lossless compression to reduce the storage size. When I try any compression method with NConvert, it changes them to 24-bit TIFF. I'm using v7.136 under Windows 7.

Is it even possible to compress 48-bit images? Or is that unsupported by NConvert or the TIFF format? I noticed the # of colors displayed when using the -info parameter is 16777216 for 48 bit images, which seems wrong to me.

Here is an example 48-bit image I'm using: https://mega.nz/file/upIGhLrJ#uMSochdL8 ... vOnDbhR-pI

Here's an example of the parameters I used: nconvert.exe -o WaterlooBridge1971compressed.tif -out tiff -c 3 WaterlooBridge1971.tif

I've tried including the -org_depth parameter but it just causes the process to sit on 13% CPU usage and never finish.

[xnview]

ok, will be fixed. But '-c 3' produces a bigger file

[DrFrag]

Thank you!