Transcript CMYK and RGB Color

CMYK
• Cyan
• Magenta
• Yellow
• Black
CMYK and RGB Color
CMYK
CMYK
CMYK
• CMYK (short for cyan, magenta, yellow,
and key (Black), and often referred to as
process color or four color) is a
subtractive color model, used in color
printing, also used to describe the printing
process itself.
• Such a model is called subtractive because
inks “subtract” brightness from white.
RGB
• Red
• Green
• Blue
RGB
RGB
• The RGB color model is an additive model in
•
which red, green, and blue (often used in
additive light models) are combined in various
ways to reproduce other colors.
The name of the model and the abbreviation
‘RGB’ come from the three primary colors, red,
green, and blue and the technological
development of cathode ray tubes which could
display color instead of a monochrome
phosphoresence (including grey scaling) such as
black and white film and television imaging.
CMYK vs RGB
• CMYK = printing
• RGB = on screen
CMYK vs RGB
• In additive color models such as RGB, white is
•
•
the “additive” combination of all primary colored
lights, while black is the absence of light.
In the CMYK model, it is just the opposite: white
is the natural color of the paper or other
background, while black results from a full
combination of colored inks.
To save money on ink, and to produce deeper
black tones, unsaturated and dark colors are
produced by substituting black ink for the
combination of cyan, magenta and yellow.
CMYK vs RGB
• Comparisons between RGB displays and CMYK prints can
•
•
•
be difficult, since the color reproduction technologies
and properties are so different.
A laser or ink-jet printer prints in dots per inch (dpi)
which is very different from a computer screen, which
displays graphics in pixels per inch (ppi).
A computer screen mixes shades of red, green, and blue
to create color pictures.
A CMYK printer must compete with the many shades of
RGB with only one shade of each of cyan, magenta and
yellow, which it will mix using dithering, halftoning or
some other optical technique; this dithering produces a
lower level of detail than the printer's dpi suggests.
Color spaces
• Color is typically organized in a hierarchal fashion, based on how
colors are mixed. A color space helps to define how the colors are
mixed, based on the medium in which the colors are used. There
are two different kinds of color spaces:
Subtractive
Additive
Color
• Color is the response of the eye to differing
wavelengths of radiation within the visible
spectrum. The visible spectrum is what we
perceive as light. It is the part of the
electromagnetic spectrum that we can see. The
typical human eye will respond to wavelengths
between 400-700 nanometers (nm), with red
being at one end (700 nm), violet at the other
(400 nm) and every other color in between
these two.
Color
• There are many different kinds of color systems, and many different
theories on color. We will get into that kind of detail in a later
column. For now we will focus on the basics, using a color wheel for
illustration purposes. There are three main components of color:
• Hue: Where the color is positioned on the color wheel. Terms such
as red, blue-green, and mauve all define the hue of a given color.
• Value: The general lightness or darkness of a color. In general,
how close to black or white a given color is.
• Saturation: The intensity, or level of chroma, of a color. The more
gray a color has in it, the less chroma it has.
Hue, Value and Saturation
Color Harmonies
Analagous
Complimentary
Triadic
Color Harmonies
• Color harmonies serve to describe the relationships certain colors have to
one another, and how they can be combined to create a palette of color.
• Complementary: A complementary relationship is a harmony of two
•
•
colors on the opposite side of the color wheel. When complementary colors
are placed side-by-side they tend to enhance the intensity (chroma) of each
other, and when they are blended together they tend to decrease the
intensity of each other.
Analogous: An analogous relationship is a harmony of colors whose hues
are adjacent to one another on the color wheel. Analogous colors tend to
be families of colors such as blues (blue, blue-violet, blue-green) and
yellows (yellow, yellow-orange, yellow-green).
Triadic: A triadic relationship is a harmony of three colors equidistant from
one another on the color wheel. Primary colors and secondary colors are
examples of color triads.