Page 15 - CC2018_WD_Look_Inside

Stage 1 Compositing Images and Artwork

There are two primary types of artwork: vector graphics and raster images.
• Vector graphics are composed of mathematical descriptions of a series of lines
and geometric shapes. These files are commonly created in illustration Note:
(“drawing”) applications like Adobe Illustrator. Vector graphics are resolution
independent; they can be freely scaled and are automatically output at the Why is this information
resolution of the output device. important? The ad you’re
building in this project
• Raster images are made up of a grid of individual pixels (rasters or bits) in will be placed in print
rows and columns (called a bitmap). Raster files are resolution dependent magazines, so you have
— their resolution is determined when you scan, photograph, or create the to build the new file with
file. (Line art, sometimes categorized as a third type of image, is actually a the appropriate settings
type of raster image that includes only black and white pixels.) for commercial printing.
When the composition is
Photoshop is what some people call a “paint” program — it is primarily finished, you will convert
used to create and manipulate pixel-based or raster images. Raster-image quality it to a resolution and
depends directly on the resolution; when you create files in Photoshop, you need to file format that is more
understand the resolution requirements from the very beginning of the process. appropriate for digital
Pixels per inch (ppi) is the number of pixels in one horizontal or vertical inch media display.
of a digital raster file. As a general rule, commercial print jobs require 240–300 pixels
per inch at the final output size to achieve good image quality in the printed piece. Some digital media
such as desktop web browsers typically
require much lower resolution, commonly
72 ppi, although monitors and mobile
devices with HD display capabilities
support higher-resolution images.
It is important to realize that you
cannot significantly increase image
resolution once a raster image has been
created or captured. When you create files
that will be used for both print and digital
media — as in the case of this project —
you should start with the higher resolution The same raster image is reproduced here at 300 ppi (left) and 72 ppi (right).
and then reduce the resolution after the Notice the obvious degradation in quality when the resolution is set to 72 ppi.
composition is complete.

open And resize An imAge

Every raster image has a defined, specific resolution that is established when the image
is created. If you scan an image to be 33 high by 33 wide at 150 ppi, that image has
450 pixels in each vertical column and 450 pixels in each horizontal row. Simply
resizing the image stretches or compresses those pixels into a different physical space,
but does not add or remove pixel information. If you resize the 33 × 33 image to
63 × 63 (200% of the original), the 450 pixels in each column or row are forced to
extend across 63 instead of 33, causing a marked loss of quality.
The effective resolution of an image is the resolution calculated after any scaling
is taken into account. This number is equally important as the original image
resolution — and perhaps more so. The effective resolution can be calculated with a
fairly simple equation:

Original resolution ÷ (% magnification ÷ 100) = Effective resolution

Project 1: Composite Movie Ad 25