Image Processing Reference
Figure 6-3 Relative imaging sizes for CIF and its derivatives.
Ever since PDA devices first appeared, users have been working out ways to play moving
video on them. The current state of the art is exemplified by high-end Palm OS-based Sony
devices, although Pocket PC handhelds are also demonstrating strong capabilities in this area.
Earlier Palm OS devices supported very low-resolution 160
160 displays and some of
these had very limited grayscale support. The display is only 4 bits deep, delivering 16 lev-
els of intensity from black to white. Video is prone to look a bit “crunchy” on these earlier
devices, but as the PDA devices have matured the current models do a remarkably good job.
Figure 6-4 illustrates visually how the screen size in PDA devices has gotten larger
with each new generation.
Modern devices are equipped with good-quality cameras, wireless connectivity, and
adequate capacity for removable storage. Sometimes phone connectivity is even provided
as well. The cameras are equivalent to low-end digital still cameras, but the quality at 1.3
megapixels is more than adequate for shooting short video sequences. This will get better
of course as the technology improves.
Typical resolutions for these devices are shown in Table 6-3.
The form factor is either square or portrait, but the devices support viewing modes
where a landscape picture is presented sideways. PDA devices have screen sizes that are
roughly 4 times the area of a video-capable mobile phone.
Video on Palm devices: http://www.manifest-tech.com/media_pda/palm_video.htm