
130 Chapter 6 Graphics
Upsampling is used to enlarge the physical dimensions of an image on a given device.
Figure 6.15 shows a dialog box from Photoshop in which image dimensions were
increased from 20 3 20 to 30 3 30 using resampling.
Since the image was enlarged, upsampling was required
to produce the additional pixels. The “pixel dimensions,”
or number of pixels described in the file, increased from
300 to 450 while the file size increased from 88K to198K.
Upsampling is also used to maintain the original physi-
cal dimensions of an image when it is produced on
another, higher resolution device. For example, an image
that ...