In article , Toby
Thain wrote:

wrote in message
. ..
In message ,
(Dave Martindale) wrote:

writes:

It's not obvious, though, when the missing values are 15-bit values.
Rather than 32,769 values, there are only about 11,000 values.

That is indeed very strange. I can't think of any reason the greyscale
representation should be any different from one channel of an RGB image.

Me neither. Just one of a series of many disappointments with PS. This
happens, I've found, with any conversion to greyscale in "16-bit" mode.
The color management is different for color and greyscale, too, so if
you switch back and forth there may be a continual loss of accuracy.

Someone should tell adobe that we have fast machines now and can work
with accurate data.

Photoshop is accurate, as far as we know.
Without your original data to test, I don't know what might have gone
wrong. But other people who are picky about their bits don't have any
problems with Photoshop.


I've tried. Their engineer insists that it's 30x faster to work with
15 bit quantities than 16 bit ones.

Which is correct (for 0..32768 representation versus 0..65535
representation).

Chris