Re: Ghosting

[P3D Gabriel Jacob <jacob@xxxxxxxxxxxxxx>]

Gregory J. Wageman writes

>I couldn't decide if you were joking or not, playing on bright light
>scaring away ghosts.  When I read you sig, I was sure you were.  But
>you also say this:

Casper writes

>>A good analogy would be anaglyphs displayed on monitors. There is 
>>similiar problems as in polarized 3d projection.

Gregory J. Wageman writes

>The problem with ghosting in anaglyphs is due to a mismatch between
>the color as reproduced by the monitor, and the color of the filters,
>right?  If the match isn't perfect, some of the off-red light (for
>example) is visible through the red filter and is seen by the wrong
>eye.  This would be uniform across the image, though, unless your
>monitor is displaying the single color differently across the image,
>or the color in the image varies, or your filters vary across their
>surface.  I'm going to assume that the problem is just a color purity
>problem, because the others are broken hardware or software.
>
>So, in my opinion this is more like de-polarization, in that it affects
>the entire image equally (like having the polarizers not quite at
>ninety degrees to each other).
 

>Rest deleted

Gabriel responds for Casper

Casper was joking regarding increasing the lamp output helps decrease
ghosting. Actually I think you are probably right that brigher lamps
make it worse, or at best, not any difference at all. Then again I 
don't have any direct experience and anything I say regarding this is
pure conjecture from what I have seen from 3d projections and movies.
You mention ghosting is due to incomplete extinction or as you
mentioned the ability of the polarizer to block light of undesired
polarization. As you also mention, ghosting is only a problem with
the brightest areas of the scene when immediately adjacent to dark
areas. If de-polarization were the problem the whole picture would
suffer and not only the brightest areas. I think it makes sense and
I believe the same thing happens with anaglyphs. The problem with
anaglyphs is very similiar to polarization. You mention that if the
color from the monitor and the color of the filters isn't perfect
there would be some crosstalk. This is true but only to the same
extent as in polarization, and the problem doesn't manifest itself
uniformly across the image as you mention. It only causes problems
as in polarization, where the their is overlap between dark and bright
parts. Where the image is is of the same shading for the two images,
the red and blue blends together and doesn't cause any color rivalary or
ghosting to the eyes.

Gabriel, posting for my friend Casper

Check out my latest anaglyph at http://generation.net/~jacob/cana3da.jpg
which commemorates the first anniversary of the big show of support for 
Canada in Montreal last year. 
 


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