Digital BW, The Print

on 9/26/01 5:37 PM, Austin Franklin wrote:

>>>>> Do you believe it is high bit justified, or just left low bit
>>>> justified?  In
>>>>> other words, does the scanner A/D give you a 12 bit value of
>>>> 0101 1010 1010.
>>>>> Does that end up in the 16 bit space as 0101 1010 1010 0000
>> OR 0000 0101
>>>>> 1010 1010?
>>>> 
>>>> What difference does it make? I was answering his question of why the
>>>> raw scan doesn't fill the whole 16bit space. Luckily, we don't have to
>>>> worry about what our images look like written out in binary.
>>> 
>>> It matters in how much space the values will occupy in the 16
>> bit space when
>>> you get them from the scanner.  If the values are low bit
>> justified, they
>>> will occupy a smaller span than if the values were high bit
>> justified.  Do
>>> you know the answer?
>> 
>> I know I for one await *your* answer (Austin) with baited breath.
>> If you can
>> explain this clearly, and why the difference yields differing
>> spans, we will
>> have come a long way.
> 
> The answer is, it depends on the scanner and the software.  Viewscan DOES
> high bit justify the data.  It really doesn't matter either way (except for
> someone like Mike who insists it's useful for him), because all the data is
> still there, in either case.  You still need to apply setpoints in both
> cases, and that will distribute the data pretty much exactly the same too.
> 
> I believe the answer is, it doesn't matter as far as data integrity goes,
> but if you happen to "like" it one way or the other, then it seems that it
> matters ;-)

I give up! You dragged this out, and tested Mike, as though this carried
great import. He answered it doesn't matter early on.

I'm still hoping you will explain in a simple coherent way, how the scanner
assigns values to the input data, how that process is affected by the
scanners bit depth, and how that shows up in the histogram. I understand
that is all of what we've been discussing, but it's been addressed in little
disparate snippets. It needs to be tied together. If you don't have the
energy for that I understand. But until that happens there may be no
conclusion. I'm taking a rest...

Todd