P3D Anaglyph Revealed

[Ray Zone <r3dzone@xxxxxxxxxxxxx>]

Dave Spacey wrote:

>(Quoting Ray Zone):  With subtractive filtration in the anaglyph, it can
>be seen that >the red lens sees the blue image and cancels out the red.
>The blue sees the red
>and cancels blue. Because a given color filter cancels out the same color
>in the photo or print it is called subtractive.

>Can somebody explain that to me?  I can't see how a red filter can do
>anything other than filter out the blue and transmit the red.  It *looks*
>red because it doesn't transmit blue.  Orright, cyan.

OK, Dave, here we go:

There are two kinds of light and color filtration:

Subtractive (pigment primaries) for print photos and printed media--
	red sees blue, cancels red
Additive (light primaries) for TV and computer displays--
	red sees red, cancels blue

>Is it that most of Ray's artwork appears to be dark objects on a light
>background, so that what you see is a complementary *shadow* of the
>object?

>Looking at the upper photo on
>"http://home.earthlink.net/~r3dzone/aob.html" supports this hypothesis.
>For those who can't go and look immediately, it's a photo of a man playing
>some form of wind instrument.  He has a light face on a dark background.
>The red image is to the left of it's partner.  Those parts which are
>further away (logically, I don't have funny glasses to hand) are further
>to the left than the foreground.  Which is what you'd expect of a properly
>windowed image if the left eye sees the red image.

Actually, that is a Susan Pinsky stereo photo of Arch Oboler holding a
rolled up copy of a 3-D comic book (as the caption states).  To further
confuse you, Dave, with the additive filtration display seen on the website
the Red channel is displayed as the Blue image and the Blue channel is
displayed as a Red image.

With additive filtration the mixture of Red, Green and Blue (light)
produces White.

With subtractive filtration the mixture of Red, Blue and Yellow (reflected
light) produces Black (OK, dark brown, as it usually works out with most
printing).  The subtractive filtration color matrix is used in 4-color
process printing as CMYK or Cyan, Magenta, Yellow and Black.

These potentially confusing principles must be understood in applying
varieties of the anaglyphic display especially if they are polychromatic
and if one is both printing the anaglyph and displaying it on a computer or
television screen.

The software engineers who developed Adobe Photoshop came to understand
these principles because there are image modes for both RGB and CMYK.  When
you print out an RGB image displayed on the computer screen the color
printer software automatically converts the screen display to CMYK of
necessity because that is what the printer uses.

Thanks, Dave, for responding to my posting and visiting the website.

Best!

Ray '3-D' Zone




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