the future of histogram - 256 levels not enough

[Casper Boemann]

On Wednesday 17 August 2005 00:59, Roger Larsson wrote:
> Lets try it this way... Suppose you usually work with 8 bit data, should
> not 64 levels be more than enough? Or why not 100 (to give percentages?)
That would be ok with me. 64 seems a bit small, but for something that is just 
a display on screen, which would just give me a _feel_ for the image. I think 
100 could be enough.

> OK, I admit my use of image viewers / editors are rather special (working
> with technical data, mostly using ImageJ, but toying with krita now and
> then).
but that doesn't mean we should ignore you or your requirements. :-)

> 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.
I don't think I quite understand what you mean.

> 1280 pixels wide screens are not that unusual, why remove the possibility
> to use more than 256 levels?
yes that is my own resolution, and boudewin, our maintainer uses 1600, but 
none of us feel the need for more than 256. Perhaps 512, but 65K seems a 
magnitude more than 1280, and what with float there the entire image could be 
between 0 and 0.001. Every pixel would then still go into the first bin.

So extending to a greater number of bins seems, to me at least, to be a waist. 
Perhaps you could suggest a way for us to do it.

Looking very much forward to some more input from you.

-- 
best regards / venlig hilsen
Casper Boemann