the future of histogram - 256 levels not enough

[Torsten Rahn]

Am Mittwoch, 17. August 2005 00:59 schrieb Roger Larsson:
> On Tuesday 16 August 2005 19.47, Casper Boemann wrote:
> Selecting buckets automatically can be quite difficult...
>
> Consider 16 bit data (unsigned or float). With a histogram of 256 levels
> you can easily end up with most data in a single bucket. This leads to
> some kind of autoscaling, like 256 levels between lowest to maximum value.
> But now you can easily get buckets that can never be filled, if your image
> has less then 256 actual levels. This kind of autoscaling will also make it
> more difficult to compare histograms from two pictures.

a practical example for 16 bit _grayscale_  data is working with DEM's 
(Digital Elevation Models) where preserving the information is important from 
a scientific  point of view:

http://www.shadedrelief.com/gtopo/gtopo.html

Although I was sure that you had to deal with more than 256 bins in the 
histogram, judging from the screenshots it seems I was wrong (although I'm 
not sure whether the fact that Photoshop can't deal with this isn't perceived 
as a restriction by people working on this kind of stuff).

-- 
Mit freundlichen Grüßen / Kind regards,

        Torsten Rahn

--
Dipl.-Phys. Torsten Rahn, credativ GmbH
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