- [Instructor] Printers use subtractive color.
The presumption is that the paper's white
which contains all colors,
so selectively hiding the colors we don't want
reveals the ones we do.
It's a bit like putting a colored gel
over a white light bulb.
If the bulb is white, and you put a blue filter over it,
you just see the blue light.
That is, you'll see the blue part of the light
emitted by the light bulb.
The filter doesn't exactly modify the light.
It just hides everything except the color you want to see.
This means that technically, the filter isn't actually blue.
It's every color except blue.
It's hiding every color except that one.
The cyan, magenta, yellow and black inks printers use
work on the same principle.
Though, of course, instead of covering up
a white light bulb, they cover up white paper.
You can interfere with this process by using
colored paper, of course,
though this would inevitably be a little bit hit and miss.
There's a black ink in addition to cyan, magenta and yellow,
because they discovered a good, clean black
couldn't be achieved by combining colored inks.
This is probably partly because of limitations
in the production of perfect ink,
but that's another story.
This is probably a good moment to mention a problem
that you will have no doubt encountered before.
RGB and CMYK don't perfectly translate.
Computers and printers do a pretty good job
of turning the RGB color your computer screen uses
into the CMYK color your printer uses,
but it's an imperfect translation.
It's a little bit like translating English into French.
When we say hello to greet someone,
this is normally translated in French as bonjour.
The two words are functionally the same,
but actually have different meanings.
Hello probably comes from an early expression of surprise,
but bonjour means good day.
These subtle and not so subtle differences
reveal themselves to be a challenge when translating
color modes, too.