ABSTRACT
The number of pixels is defi ned as pixels per inch/PPI. After the
image fi les are downloaded to a computer, the computer’s internal
video card automatically converts the image fi les into display pixels
that are shown in varying percentages of the original picture fi le. The
most accurate display occurs when a picture fi le is displayed in even
screen-resolution multiples such as 100, 50, and 25 percent. Uneven
screen-resolution displays, such as 33 or 66 percent, will generally
exhibit jagged edges because the computer will use anti-aliasing to
approximate the partial pixels. When you want to utilize this digital
data to make a print, the computer’s printer software then converts
the digital image fi le into dots per inch/DPI, enabling the virtual
image to be physically rendered onto paper by means of dots and
inks (see Box 8.1). It is important to clearly understand the differ-
ences between pixels per inch (PPI) and dots per inch (DPI); these
differences will be discussed in more detail later in this chapter.
