Color depth info

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Bit depth is a huge tarball (like most everything else concerning metadata). I last investigated it two years ago:

https://www.lightroomqueen.com/community/threads/adobe-reports-16-bit-on-14-bit-gfx-100-shots.43767/post-1289764 

The Metadata panel field Bits Per Sample is the number of bits per sample for DNGs only (it appears in the panel's DNG tagset, and has the internal name "com.adobe.dng.bitsPerSample").  The field is supposed to represent the number of bits used by the camera sensor. LR computes DNG Bits Per Sample using the formula ceiling (log2 (WhiteLevel)), where WhiteLevel is a DNG parameter.

What Exiftool and Rawdigger (which uses Exiftool) report as Bits Per Sample for a raw or DNG is the number of bits used to store a sample in the file, not the number of sensor bits. Many cameras whose sensors are 12- or 14-bit use 16 bits to store samples in the file. I believe that for raw formats that use lossless compression, this is the number of bits per sample after uncompression.

LR has a smart-collection criterion Bits Per Channel that shouldn't be confused with DNG Bits Per Sample. It represents:

- For DNGs with mosaic (sensor) data, the number of sensor bits (that is, DNG Bits Per Sample).

- For raws, it always reports 16 bits, even if Exiftool shows a smaller value for Bits Per Sample (see the second screenshot below). (I've tested this with my sample catalog, which has 22 camera makes and 262 models.)

- For all other file types, the number of bits per channel used in the file. But for all the raws in my test catalog (22 camera makes, 262 models), Bits Per Sample is 16.

LR doesn't show Bits Per Channel in the Library Filter Metadata browser or in the Metadata panel. But last year Adobe finally exposed it to plugins. So (as you might guess) you can view it in the Filter command of the Any Filter plugin:

(Beware that LR 13.1 broke an important feature in the plugin SDK, and the Filter command will give lots of spurious errors, though eventually show you the right results. I'll be releasing workaround in the next day.)

Don't you miss the good ole days when companies paid experienced tech writers to maintain complete and accurate technical documentation?  (Yeah, and I walked to school 10 miles each way in winter blizzards.)