Apple Aperture Digital Photography Fundamentals - Manual (Page 36)

36 Chapter 2 How Digital Images Are Displayed
Displaying Images in Print
Displaying images in print requires converting the color from the RGB color space to
CMYK. The reason for this is that printed images need to reflect light from external light
sources to be viewed. Images are usually printed on white paper, so no white ink is
necessary. Darker colors are created by adding colors together, whereas lighter colors
are produced by reducing the color mix.
For additional information about image quality in print, see Chapter 3, “ Understanding
Resolution ,” on page 37.
Printer Types
The following printer types are divided into two groups: personal printers and
professional printers.
Personal Printers
There are two basic types of printers that are affordable for most photographers.
 Inkjet: Inkjet printers create images by spraying little ink droplets onto the paper.
Inkjet printers are capable of placing the microscopic droplets on the paper with
great precision, resulting in high-resolution photographs. There are two methods of
applying the ink to the paper. One technique involves heating the ink to a
temperature warm enough to allow the ink to drip. The second method involves
vibrating a tiny valve filled with ink, forcing it to fling a droplet onto the page.
 Dye sublimation: Dye sublimation printers create images by heating colored ribbon
to a gaseous state, bonding the ink to the paper. The ribbon is a plastic material
that makes the print nearly waterproof and difficult to tear. The incredible
durability of dye sublimation prints gives them a longevity that cannot be
surpassed by any other medium.
The quality of inkjet printers has improved remarkably in the past few years, making
their resolution and color gamut superior to those of dye sublimation printers.
Professional Printers
There are two basic types of printers employed for professional use. Unlike personal
printers, these printers are relatively expensive.
 Offset press: Offset presses are used for high-volume printing for items such as
magazines and brochures. Offset printing presses deposit ink in lines of halftone dots
to produce images on the page. The printer uses a fixed drum to roll the image onto
the paper.
 RA-4: RA-4 printers are capable of printing digital files on traditional photographic
paper. They use a series of colored lights to expose the paper, which blends the
colors together to produce continuous-tone prints. Due to their expense and size,
most photo-direct printers are only available at professional photo labs.