Introduction:
A "normal" image is two-dimensional. All positions
on the image can be located by their X and Y coordinates. A three-dimensional
image has another dimension, Z, which is required. In terms of
your computer screen, X is horizontal position, Y is vertical
position, and Z is the position into or out of the screen. Getting
that extra dimension into an image is tough; usually it takes
two images from different perspectives to accomplish that, but
using two images doubles the image overhead. ChromaDepthTM 3-D
takes a much more efficient approach by using color to carry the
Z position information. This is called encoding depth into color.
This Image Design Guide will explain how you can design your
own images that will show great 3-D when viewed with C3DTM Glasses.
There are two parts to the ChromaDepthTM 3-D process: designing
the colors of an image according to ChromaDepthTM 3-D, then presenting
and viewing the image with C3DTM Glasses. The first step - designing
the colors of the image - is much easier than it sounds. First,
you choose a color palette (go to the C3D TM Color Palettes page
for a thorough primer on this). There are different color palettes
to produce the best holographic effects for a selected background
color. There are probably an infinite number of color palettes
that could work, but the simplest and most dramatic is RGB on
Black. This stands for Red-Green-Blue on Black Background. In
the ChromaDepthTM 3-D process the color of an image element and
that element's immediate surrounding color determine its C3DTM
depth position. If we keep the background color constant around
each image element, then the color of the element alone will determine
its Z dimension.
Background Color and Color Palettes:
The choice of background color is the most important factor
in determining the colors which should be used to achieve ChromaDepth
TM 3-D and CyberHologramTM effects. The easiest and most commonly
utilized background colors are black and dark blue. The color
palette, RGB on Black/Blue, apply to both of these background
colors. If dark blue is used, it must be a very pure, very dark
blue. The effects will not be the same for a sky blue, medium
blue, or other light blue. The reasons for this are explained
in the section on Tint and Depth Position.
On a black or dark blue background the ChromaDepthTM color palette
uses red for the most foreground object, dark blue for the most
background object, and green for the middleground. The other colors
fall in between according to the colors of the rainbow. (Thus
one could use red, orange, yellow, yellow-green, green, blue-green,
blue, and dark blue, in order, from foreground to background).
An infinite number of colors may be used to divide the space between
red and blue. Contoured or rounded surfaces can be shown by smoothly
blending from one color to another across the surface. Be sure
to use black patterns on the surface to help define its shape;
see Use of Black for details.
Another color model that is very effective on a black background
is the 'Patriot' color model; Red-White-Blue on Black. See the
C3DTM Color Palettes page for details.
When a dark blue background is used it is important to incorporate
some black pattern on the blue in order to locate the background
in depth space. Without a black pattern the blue background seems
to be undefined space; it occupies some nebulous 'back there'.
The black pattern provides edges for your mind to locate in space,
enlarging the apparent depth. For more on the use of black and
the importance of creating edges, see the section on The Importance
of Black and How to Use it.
On a white background the ChromaDepthTM color palette is the compliment
of the color model for a black background. This makes the key
colors cyan, magenta, and yellow (CMY; the compliments of red,
green, and blue, respectively), so this is called the Cyan-Magenta-Yellow
on White color model. (Our Crayon CyberHologram TM page illustrates
this nicely, with crayons and crayon drawings!) The inverse color
function on many computer graphic design programs can take a normal
black background ChromaDepthTM colored image and convert it to
a white background, CMY on White ChromaDepthTM image.
But be warned; although the CMY on White 3-D effect is as strong
as the RGB on Black 3-D effect, the images created with CMY on
White sometimes may look unnatural. The RGB on Black color palette
follows the colors of nature and of normal artistic design, but
try both color palettes.
Using Outlines as Local Backgrounds:
A very good way to simplify dealing with backgrounds is to use
black or white outlines around image elements. This effectively
gives each element its own 'local background', so that no other
color can contact the fill color which is inside the outline.
The choice of black or white for the outline color depends on
the color model used: the outline color should be the same as
the background color in that color model. The width of the outline
needed will depend on lots of factors, and can only be determined
by a little experimentation.
Using outlines as local backgrounds is especially valuable when
creating animations in which objects may pass over each other.
The outlines keep general CyberHolographicTM weirdness from breaking
out. (Of course, that can have its own appeal.
Depth Cueing:
Using normal two dimensional depth cues in an image can dramatically
augment the depth created by the glasses. These include shading
for roundness, perspective and forced perspective effects, overlap,
changing size as depth is changed, including shadows of one object
on another, and increasing the brightness of colors as objects
are brought closer to the foreground.
It isn't always necessary to change the color of an object as
it is moved closer or further in depth. An object moving from
the background to the foreground could be designed to increase
in size as it moves up the color palette from blue through green,
yellow, orange, and red. Once it becomes red, you can continue
to force the apparent movement in depth by continuing to increase
the size of the object, even though you are no longer changing
its color. The strong depth cue created by increasing the object's
size continues to fool your brain into seeing the object move
forward even though there is no change in the C3DTM created depth.
Similarly, shrinking the size of an object while smoothly changing
its color from red down the rainbow to blue will make the object
appear to recede into the distance. Continuing to shrink the
object after it has reached maximum blue will continue the illusion
that it is moving away.
Combining size change with brightness variation can achieve even
more dramatic results. Make the object darker when it is supposed
to be far away and brighter when it is in the foreground. There
is an easy way to accomplish this if you use a 3-D rendering program
like 3-D Studio, Lightwave, Wavefront, Truespace, Raydream, or
Polyray: turn on fog and make the fog color black. Experiment
with the fog density and its near and far planes to get the effect
you like.
With strong two dimensional depth cues it is even possible to
keep the sense of real stereoscopic depth while mixing up the
colors, such as placing an orange object behind a yellow one by
use of perspective and shadows. It does not always work, but
it can be worth trying. Be aware, though, that if you try to
push this too far the effect may break down.
Avoiding the Image Border:
The border of an image generally appears to be at the middleground
position. Any object colored to appear at middleground or deeper
can be clipped by the border without any visual problem; it looks
like the border is a frame above the object, like it is in a shadow
box.
Any object that is colored to appear closer than middleground
should be kept away from the border because it will appear to
snap down to the border where it touches it, losing the depth
effect (incidentally, this is true for all 3-D processes, not
just ChromaDepthTM and CyberHolographyTM ). Adding a red or black
border around the image can reduce this problem. In a moving image
a red object can move off-screen across the border if it moves
quickly; your mind doesn't have time to figure out that crossing
the border was a problem.
Handling Highlights:
In two-dimensional art, highlights from shiny surfaces are
normally shown by a white spot or white starburst. This causes
a problem for ChromaDepthTM images because the color white tends
to the middleground of the image. This means that a white highlight
on a blue object will look like it is floating off of that surface,
while a white highlight on a red surface will look like a bright
point inside of the red surface. Highlights can be used with ChromaDepthTM,
but they usually aren't colored white.
There are two main methods for showing highlights, and they can
be combined in different amounts according to taste. The first
approach is to select the highlight color to be slightly closer
than the surface it is on.
Here is how it works: the highlight on a surface should be just
slightly closer than the surface, so it is necessary to use highlights
which follow the ChromaDepthTM 3-D color/depth palette. We have
found that using a color which is five (5) percent closer (closer
means 'towards red') than the highlighted surface is quite effective.
For example, if the scene has been divided into twenty depth zones,
a five (5) percent closer highlight would use the color of the
next closest depth zone. For one hundred (100) depth zones you
would move closer by five (5) depth zones for the highlight. For
more information on the color models see our Color Palettes page.
The second method is to keep the color the same as the surface,
but to increase the brightness. This works well for TV and video,
since the main object colors need to be slightly muted (by adding
black to shade them down) to keep them 'NTSC legal'. NTSC illegal
colors 'bloom' on the screen, blurring past their intended boundaries.
This is fine for a highlight, so using NTSC illegal color brightness
for highlights works well to emphasize the extra brightness of
the highlight. With a little finesse, these two approaches can
be combined with good results.
The Importance of Black and How to Use it:
Black is extremely useful to the CyberHolographic TM artist.
Here at Chromatek we say that 'black rides with the color it is
on'. If you put a black spot on a red area the black spot will
appear to be at the same forward depth position as red on black.
If you put a black spot on a blue area the black spot will appear
to be at the same background depth position as blue on black.
Wherever possible, black should be used to outline colors which
are on a black or dark blue background. In a similar manner, white
should be used to outline colors against a white background.
When the human brain compares the differences in the images of
a stereo pair in order to determine what depth should be perceived,
it is the edges of objects and other high contrast vertical features
which are compared. If you want to blend colors across a surface
to show roundness or bending, it is very effective to add some
black lines into the surface to provide the edges that convey
the depth. For example, if you want to show a ball that has roundness,
you can blend from red at the closest point around to yellow at
the edge, then add black shading or crosshatching lines as would
normally by used to indicate roundness in a two dimensional image.
If the weight, or thickness, of these black lines is adequate,
the lines will allow your mind to see the height differences by
the color blending in a very effective manner. (Very fine black
lines may blur and disappear when viewed with the C3D TM Glasses.
This is less likely with HoloPlayTM Glasses.)
Tint and Depth Position:
In the jargon of color, tint refers to taking a pure color
and adding white to it. The resulting lightened color is a tint
of the original. Tints can be used to broaden the range of colors
which appear to lie at a given depth position and to give textured
effects to surfaces. Here is the lowdown:
We will first presume that we are working with a black or dark
blue background. Under these circumstances a white object will
appear to be in the middleground position, about equally spaced
between the foreground and the background. Adding white to any
color 'pulls' that color toward the middleground. The degree to
which the color is moved toward middleground depends on the amount
of white added to it. A little white only moves the color a little,
much white moves it far. Since the colors are pulled toward the
middleground, each color reacts to tinting in its own way. Reds
and oranges move further away, since they are forward of middleground.
Yellow and yellow-green don't move much since they are already
about at middleground. Greens and blues move closer with tinting,
since they are normally in the background, behind middleground.
All colors end up at middleground as they are tinted completely
to white.
An extremely effective use of tint is to add texture to a dark
blue background by tinting areas, making them lighter blue, to
show raised portions. A surprisingly small amount of added white
will result in definite and pleasing depth change for blue. This
can be easily accomplished in most graphics programs with the
emboss function if you have control of the highlight and shadow
colors. Don't forget to include some black in an embossed blue
pattern to help define the location of the darkest blue.
Shading and Depth Position:
The opposite of tint is shade; a shade of a color is created
by adding black to a pure color. Shading a color tends to move
that color further away, in proportion to the amount of shading,
regardless of whether it is a foreground color or a background
color. A dark shade of red won't move all the way back to the
position of blue, but it will appear deeper than a bright red.
The reason that shading creates this effect probably depends
on our familiarity with shadowing to show roundness. Use shading
with care; if an image element's color is shaded darker than the
shade of its local background, then the background color will
predominate in determining its perceived depth position.
Color Quirks:
Red on yellow, with no black border between them, has an ambiguous
depth position. It tends to look like the red is inside of the
yellow area, down about at middleground. A black border restores
the colors to their expected positions. Red on green can have
the same trouble as red on yellow if there is no black border
separating them. The controlling factor is the brightness of the
green. A bright green will behave more like yellow, a dark green
will behave more like blue.
Red on dark blue works without a black border. Light blues, or
light tints of other colors, can produce a similar effect to yellow's,
so use a black border whenever there is any question. Magenta
on black typically looks like a crisp, red object surrounded by
a fuzzy blue halo. We don't recommend using magenta unless you
are seeking that kind of effect.
Creating Readable Text:
Black on white is the normal choice for text, but when using
HoloPlayTM Glasses or C3DTM Glasses this combination is singularly
difficult to read . The choice of font and size is important,
too. We recommend Arial font, size 8 to 12 point, bold. We recommend
any of the following color combinations for good readability:
1. Black or dark green on light cyan ([R,G,B]= [204,255,255]):
(Easy on the eyes, both with and without ChromaDepthTM Glasses.
It also prints well.)
2. Green on dark green background:
(This is the easiest color combination on the eyes, both
with and without ChromaDepthTM Glasses. It does not print well,
though.)
3. Dark green or black on green background:
(Also easy on the eyes. It prints better than number 1,
above.)
4. Red text on black background:
(This is dramatic, but can be hard to look at for a long time.)
5. Black text on red:
6. Magenta on white:
7. Cyan on white:
8. White on magenta:
Above all, nothing can take the place of lots of experimenting!
NOTE: ChromaDepthTM and ChromaDepthTM 3-D are both used to
refer to the process of coloring images according to ChromaDepthTM
3-D image design criteria, also called the Open CyberHolographicTM
Standard. HoloPlayTM and C3DTM refer to the unique and revolutionary
micro-optic glasses manufactured by Chromatek Inc. which are used
to see the holographic effects of CyberHologramsTM and C3DTM images.
ChromaDepthTM, C3DTM, CyberHologramTM and the grammatical variants
of these terms are trademarks of Chromatek Inc., with all rights
reserved.
Chromatek Inc., 1246 Old Alpharetta Road, Alpharetta, GA 30005,
USA
(770) 772-9852, 1-888-NOW-UC3D, (770) 663-4726 Fax
email: c3d@chromatek.com