Gilles Tran wrote:
> I ended up raising the
> brightness to 2 and lowering the Kari Kivisalo light intensity.
I have a theory on why these changes were necessary to produce more
pleasing image than the "scientific settings".
We are used to looking at photographs on paper which have contrast
ratios ranging from 4 to 100 depending on viewing conditions and the
quality of the paper and print process.
Contrast ratio is the ratio of luminance between the brightest white and
the darkest black of a particular device or a particular environment.
Human vision can operate in an environment with a several hundred times
larger contrast ratios. Considerable research has gone into capturing
this huge dynamic range on paper with limited range so that the image
still appears natural or acceptable to the viewer.
Some kind of compression is clearly needed to "zip" a dynamic range
of a scene on paper. The most logical place to start is to limit and
compress the high intensities. Look at this graph from Kodak:
http://hammer.prohosting.com/~kkivisal/trans1_rgb.gif
Density 0 is the maximum value and density 2 is 100 times dimmer than
the maximum value. The high intensities are considerably compressed
(notice the log exposure).
--------------------------------------------------------------------------
Computer monitors can display images with contrast ratios 5-170 which
is quite similar to photographs on paper. My theory is that to get natural
looking images we should emulate the compression scheme used in photographs
as a post processing step and use the "scientific settings" on a scene.
--------------------------------------------------------------------------
Gilles' tweak is essentially a compression scheme and this is why the
scene looks better.
Once I get 48bit pov output to Matlab I will test my theory. If someone
knows this isn't going to work please tell now :)
______________________________________________________________________
Kari Kivisalo http://www.kivisalo.net
Post a reply to this message
|
