I have a similar problem, that the file is not recognized correctly. It is a multi-page 16-bit grey tiff but nconvert idetects it as 16Bit (with or without -org_depth). Can I set the input format somehow and prevent nconvert from any conversion?
I would like to extract all pages and save the tiffs as 16Bit without any conversion to 8-Bit.
Otherwise I am very happy with nconvert, it extracts all pages and writes all exif/meta data!
identify ./DJI_0018.TIFF
./DJI_0018.TIFF[0] TIFF 640x512 640x512+0+0 16-bit Grayscale Gray 2.16959GiB 2.830u 0:10.921
./DJI_0018.TIFF[1] TIFF 640x512 640x512+0+0 16-bit Grayscale Gray 2.850u 0:10.928
nconvert -v -i -ctype grey -org_depth -in tiff ./DJI_0018.TIFF
** NCONVERT v7.39 (c) 1991-2019 Pierre-E Gougelet (Feb 25 2020/13:19:45) **
Version for Linux x86 (X11) (All rights reserved)
A TIFF (RGB) was recognized : ./DJI_0018.TIFF
Width:640 Height:512 with 256 colors
Nplanes : 1 Bitscount : 8
Bytes Per Plane : 640
xdpi : 0 ydpi : 0