16bit BW converted to TIFF-ZIP downgraded to 8bit and look inverted in mac

[teoteo]

Hello, I was converting some images using XNconvert from uncompressed tiff to zip tiff. I noticed that some of them on my mac finder and in mac preview app, looked like negatives, inverted. In other apps like XnView or lightroom they looked fine. So I checked a little and found out that the all the files that looked odd, were originally 16bit Grayscale but were converted to 8bit RGB. (the 32bit color looked ok). I tried some different settings, the output in PNG and the TIFF compressed in LZW looked fine in finder but were also 8bit. I tried to convert to TIFF, setting the B&W conversion to 'none', but the file output were still 8bit (grayscale), and half the size of original.
Any clue on how to work that around, in particular how to compress TIFF keeping the 16bit format?

Thanks!

[xnview]

Hello, I was converting some images using XNconvert from uncompressed tiff to zip tiff. I noticed that some of them on my mac finder and in mac preview app, looked like negatives, inverted. In other apps like XnView or lightroom they looked fine. So I checked a little and found out that the all the files that looked odd, were originally 16bit Grayscale but were converted to 8bit RGB. (the 32bit color looked ok). I tried some different settings, the output in PNG and the TIFF compressed in LZW looked fine in finder but were also 8bit. I tried to convert to TIFF, setting the B&W conversion to 'none', but the file output were still 8bit (grayscale), and half the size of original.

Could you send original and converted files?

Any clue on how to work that around, in particular how to compress TIFF keeping the 16bit format?

you can't, only with NConvert

[teoteo]

Here are the original and Zip converted and a couple screenshots on how they look.

https://mega.nz/folder/3QlRhKAQ#BCRUcWPtuCgfNVJi4L2yQg

[xnview]

Strange, i've tried and the colors are inverted on photo app only when using ZIP compression, i don't understand why?