Image quality -
PC camera has to faithfully reflect and
reproduce true color of observed object, any distortion of image or
twisted of color will consider being poor image quality. Since the
responses of human eyes to color are slightly different, some testing
equipment and environment is necessary to accurately judge the
image quality. Nevertheless, image sensor, lens and design method
is the key factors of image quality.
Another criteria of image quality is the sensitivity to environmental
luminance, some PC camera can sense the image in dim condition
for light source as low as 5 luxs, while others can respond in 10 luxs
only.
Lens -
Lens is another critical component in PC camera that can
affect the quality of image sensed. The focal length and
viewing-angle of lens, associated with IR-cut and low-pass filter,
will determine the picture quality sensed. The most popular lens
used in PC camera market is 1/3”,1/4” and 1/5” lens, with 3.6 ~ 6.0
mm focal length each has their own advantages in different
applications. To avoid distortion on edge of image, focal length
above 4.0 mm is recommended.
Performance and resolution -
The performance of
PC camera is determined by frame size (resolution) and
frame-per-second PC camera can handle. Frame size has certain
standard for comparison, so-called SQCIF (160 x 120), QCIF (176 x
144), CIF (352 x 288) and VGA (640 x 480). Analog PC camera can
transmit up to 30 frames/second at any resolution, which is almost
the highest quality similar to the motion picture as you see in the
cinema.
Still 18 frames/second claims to be acceptable in digital PC camera,
although some jerking image may occur and cause inconvenience
for visual effect. The new USB or parallel port PC camera with
compression technologies should be able to support up to 30
frame-per-second in CIF formats.