RE: 3D SPEX (and LCS in general)

[P3D Andrew Woods <andrew@xxxxxxxxxxxxxxxxxxxxx>]

Firstly I'd like to say that I like all 3D-PC systems (interlaced, page
flipping, sync doubling) because they all offer 3D.  
However, each system has it's pros and cons.  One system may be easier than
another in a particular application, and yet more difficult in another
application.  Choosing the BEST system will depend upon an individual's
requirements and budget.  Why does is this starting to sound like the
Realist vs. ..... debate?

With that in mind, there are a few items of fact that should be 
questioned.

John Urbanic <URBANIC@xxxxxxxxxxxxxx> wrote:
> I wasn't claiming that sync-doubling was the cheapest, just
> the highest quality.

Page Flipping Systems which switch at 100 or 120Hz offers the highest 
quality - since they show full resolution in both fields.  
Sync-doubling offers half this "quality".

But, of course, you have to have the appropriate equipment to be able to do 
page flipping at 1024x768 at 120Hz...

<nit picking mode on> sync doubling is slightly less than half resolution
because the extra sync pulse (and it's requisite blanking interval) take
up otherwise valid lines <nit picking mode off>  Of course, you can always
use a higher res. mode to allow for this but then you would be using a
non-standard mode.

> As for the tradeoff in vertical resolution.  I should make two points before
> anyone gets too confused.  First, the total image resolution remains the
> same as for a 2D picture, say 1024x768 (the minimum resolution we use for
> educational materials).  Each eye only sees half of the vertical resolution,
> but the total amount of information that your eyes/brain get to see is
> 1024x768 truecolor pixels, giving at least the image quality you would
> expect from a 1024x768 2D image (and that's not bad).

Yes it appears to be true that a 3D half resolution image appears
to have approximately the same resolution as a 2D full resolution image.
(I use field-sequential 3D video all the time and am always thankful
for this principle.)
But if you also compare a 3D full resolution image to a 2D full
resolution image you will certainly notice the difference.

> DON'T USE LOSSY COMPRESSION FOR 3D.

I can't help but notice some double standards cropping up here.
First you say that it's OK to use 3D at half the vertical res. of 2D
images but then you say that you need higher quality images in 3D than
in 2D...

The advantage with JPEG compession is that the user can dial up the
amount of compression they need for a particular application.
If you can afford the disadvantages of large file size (long download,
more space on you hard drive) then use the maximum quality (least 
compression).  If you need the image to have a small file size and
can afford the lower quality, use a higher compression ratio.

I can say now that I wouldn't be viewing all the wonderful 3d images
on VREX's www.3dexpo.com site if the images weren't compressed.
As an example, my vote for the best image on the site goes to:
 http://www,3dexpo.com/gallery/gallery_xav/xav_02h_640x480.htm
    As a lossy compressed stereo JPEG file it is 61kb
    resaved as a loss-less compressed TIF file it is 386kb
    and resaved as an uncompressed TIF file it is 901kb.

I'd still like to hear more about the .neo format.
Are there any details available?

Cheers for now,
Andrew Woods.               http://info.curtin.edu.au/~iwoodsa


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