Am 21.03.2011 17:39, schrieb gregjohn:
> .... use all the 256 grey scale values. ?
>
> 1) I noticed that on scanning electron microscopes (SEMs), there is often "Auto
> Contrast / Brightness" settings.  When you use it, I find that it often gives
> you a histogram that "wastes" at least a third to half of the 256 grey scale
> values, with at least the top and bottom 1/6 unused.

Don't know about this one.

> 2) I looked at some NASA images from the Mercury mission. ( http://is.gd/cgqJdp
> ) I noticed that for most of the images, they too left unused half of the 256
> values.

Maybe those images are calibrated to some physical units?

> 3) Then there is the never-ending controversy over calibrated monitors.
> Shouldn't people save time, and just tweak the lighting in the scene so that  a
> proper distribution of grey (or RGB) values are used?
>
> Am I missing something or is everyone else in the world missing something?

You're missing that one and the same image will look differently on any 
two uncalibrated monitors. You can tweak your scene all you want, but if 
the monitor it will later be displayed on (or actually the display 
subsystem as a whole) doesn't happen to be set up for the same white 
point, black level and gamma you used, the scene will inevitably look 
different from what you intended, and all your tweaking will be in vain.

The ideal solution for this problem would be to calibrate all displays 
in the whole world to one and the same set of well-defined settings, so 
that "what you see is what others get".

An alternative is to calibrate all displays in the whole world to /any/ 
well-defined settings, attach information to each image what settings to 
best use for display, and have image viewing software automatically 
compensate accordingly for the differences in the display settings.

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