>Having been the lone voice in the wilderness promoting 12 bit when everyone
>else was 8, this thread is just too tempting.

>If the validity of an observation hinges on one in 256 grayscales let alone 1
>in 4096 it is not worth publishing.  And the subtleties of image quality are
>not going to show on thumbnail journal images.

It needs to be clearly stated that
1. 8 bits per channel is more than enough for excellent picture quality.
2. Higher bit levels have little to do with pictures and a lot to
do with NUMBERS.  To take a very simple example, suppose we want to put
a numeric value on the intensity difference between our experiment and
our control.  The experimental material will (we hope) be very bright
and the control very dim.  We have to set our gain and PMT voltage to
capture the bright image without overflow, and as a result our control
data is captured with maybe only 1 bit of information!  We cannot make
a meaningful comparison (and probably can't get a printable picture of
our control either!)

>With our latest offering (the TR) we collect from the PMTs at 10 bit, and
>after averaging, shunt the data around and process it at 8- bit resolution.

Leica made a similar point.  Averaging into 16 bits than converting to
8 for storage makes a lot of sense for many purposes.  However unless
the scaling factor is also stored we cannot use this for numerical
purposes.  Do these systems store this factor and use it in numerical
calculations?  Vendors' comments would be welcome here.

But if you are going to provide 16-bit hardware why not give the user the
option of saving the 16-bit data?  RAM is cheap.  Operating systems and bus
widths are 32 bit these days (and have been 16-bit for YEARS).   Do you hate
Polaroid Corp so much that you want to reduce the numbers of ZIP disks sold?
The expensive part is already there - why not make full use of it?

                                                        Guy Cox

Dr. Guy Cox,   |                    ooOOOOOOoo
E.M. Unit, F09 |        #       oOOOO  |  |  OOOOo       #
Univ of Sydney |       ###    OOO|  |  |  |  |  |OOO    ###
NSW 2006,      |       ###  OOO  |  |  |  |  |  |  OOO  ###
Australia      |       ### OO |  |  |  |  |  |  |  | OO ###
Phone:         |      #####   |  |  |  |  |  |  |  |   #####
+61 2 9351 3176| =====#####============================#####=====
Fax:           |      #####                            #####
+61 2 9351 7682|    ~~#####~~~~~~~~~~~~~~~~~~~~~~~~~~~~#####~~