Choosing Your Application AXIS 2420 User’s Manual

32

Picture frequency for Networking Applications
When used in a TCP/IP networking environment, the AX IS 2420 delivers up to 30/25
(NTSC/PAL) images/second. The perceived frame rate in your browser is typically limited
by:
• the number of clients accessing the images
• your computer and browser
• the chosen image resolution and compression
• the lighting conditions at the point of installation
• available network bandwidth
• the complexity of detail and color variation within the image
Note: The AXIS 2420 is available in NTSC and PAL variants to accommodate the different power supply
frequencies in the USA and Europe.

Image Compression Ratios

Although the file size of a JPEG-compressed image depends upon the actual content of the
image, images containing great detail generally generate larger files. Image quality is
largely controlled through the level of compression; where high compression yields small
files, and low compression maintains higher image quality at the expense of larger files.
The table below is derived from real-life tests, and defines the average file sizes for each
supported image resolution:
* Maximum performance for a single viewing client.
Note: Using a modern computer will avoid introducing any unnecessary constraints on the image fre-
quency.
NTSC PAL
Resolution File size (kb) Max fps* Resolution File size (kb) Max fps*
4CIF (704 x 480) 7 - 150 10 4CIF (704 x 576) 8.5 - 180 8
CIF (352 x 240) 1.4 - 40 30 CIF (352 x 288) 1.7 - 50 25