Color
White Light
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White light is a mixture of all colors of visible
light.
Black is the absence of light.
This font is black because no light is shining
here.
The light shines all around it making white.
Mixing colors
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By mixing different colors you can create
new colors.
The goal for a printer make as many colors
possible out a few starting colors.
Out of 3 colors we can make all colors.
Color by subtraction
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Pigments (dye, ink) absorb certain
frequencies of light and reflect others.
Yellow pigment reflects yellow light and
absorbs other colors.
When you add another pigment it subtracts
a color by absorbing it.
If you mix all colors perfectly you should
get black.
Subtractive primary colors
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You can make almost any color out of
different concentrations of Yellow, Cyan,
and Magenta pigment.
Art has long used Yellow, blue, and red.
Both of these sets are shades of the other.
You can make yellow, cyan and magenta
from yellow, blue and red.
You would just use more of one color and
less of another.
Where you will see the
subtractive primary colors
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Every color printer has 3 cartridges (some
also have a 4th black cartridge)
Those colors are cyan, magenta and
yellow.
The 4th cartridge isn’t really necessary,
however it was quickly found that 99% of
printing is in black, and replacing one
cartridge is cheaper than replacing 3.
Mixing the subtractive primary
colors in equal concentrations
Yellow
Red
Magenta
Black
Blue
Green
Cyan
*It will make this section easier if you cut light
down to these six colors
Mixing subtractive Primary colors
More mixing
Red reflects
yellow and
magenta
Red
light and absorbs
cyan
Magenta
Yellow
Black
Blue
Green
Cyan
If you mix cyan and
Cyan reflects cyan
red all colors will be absorbed and absorbs magenta
so you will get black.
and yellow
Filters
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A filter is something like colored glass
or plastic.
Color filters allow certain colors to pass
through and absorb others.
They work the same way pigments do,
except pigments reflect color, where
filters transmit color.
The hidden message trick
These are made of several dots and lines
The ones that
reflect red
When you put a red filter on
top of it, all that reflect red
will appear red, cyan will
appear black, because it
absorbs the red light.
And cyan
which absorbs red
Homework
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Read section 28.1-28.3
pg 575
1-7; 14-20