Web Camera Image Detection
Introduction
The web camera, or webcam, is most generally used to facilitate mass
communication or image exchange. It is most commonly used for household applications
such as web conversations or in small businesses as inexpensive surveillance
equipment. While the vast majority of the design and operation of the webcam has
remained constant since its invention, more recent years have given rise to
improvements upon the basic design such as faster image transfers and improved
image detection algorithms.
Webcam Applications
General
Webcams find use whenever visual monitoring of a distant location is required.
One of the biggest emerging uses for these devices is in the area of surveillance and
event detection. Various research efforts, such as the one at The University of
Jerusalem [1], have made great strides in developing “intelligent monitoring” systems
that are able to detect when important actions (sudden movements, unidentified sounds,
etc…) occur. With this technology, security cameras in private facilities or public areas
could automatically assemble a summary of a day’s important activities instead of an
attendant having to constantly monitor or review security footage, or a webcam in a
baby’s room could monitor if the baby has accidentally left the crib.
Because of their inexpensive nature, web cameras have also found use in the
area of impaired speech recognition – translational tools to facilitate communication for
the hearing impaired. Companies such as IBM [2] have developed technology to
effectively translate visual speech into written text (i.e. ‘lip reading’). The first prototype
unveiled in 2007 was capable of recognizing 10,000 common spoken words in the
English language, and could translate the sentences in to sign language images so they
could visually be interpreted by the hearing impaired.
Government/Business
The growing use of webcams has forced the price of the average webcam to
sharply drop. Several small businesses in the past four years have taken advantage of
this improvement and have implemented reduced cost security systems [3] [4].
Webcams can now easily communicate with security systems and even mobile phones.
Therefore, with the aforementioned image detection technology [1], webcams can easily
detect security threats or hazards and relay important information to necessary contacts.
The reduced cost comes from the ease of setup and the inexpensive nature (less than
$100 for medium range quality) of the webcam as opposed to the high cost of
surveillance cameras (greater than $500).
Webcam Technology
Basic Operation
The basic webcam design [5], largely unchanged since its first unveiling,
operates on the basic design of electronic cameras [6]. Analog cameras record the
incoming light with a filter and then convert the image to digital form for relay and
display. This method is cumbersome and results in playback of less than 22 frames per
second. Digital webcams require no conversion process and can not only operate with
higher frame rates (approx. 30 frames per second), but can also provide greater image
resolutions (4.0 Mega pixels) because a large amount of data can be transferred at
once. Additionally, image stabilization (anti-vibration) technologies are more easily
implemented with digital filters because the equivalent analog implementation would
require large larger electrical components.
Recent Improvements
Large improvements have been made since 2006 in the efficiency of webcam
transfer rates. The ability to implement compression algorithms, such as the one
described by Mann [7], before image transfer has given rise to more versatile web
cameras. One advantage of higher transfer rates has been to use web cameras to
transfer dynamic (moving) images as opposed to generally static (still) images,
effectively transforming the web camera into a full-fledged camera [8] [9]. Concurrently,
better image smoothing filters for higher frame rates have been implemented in
webcams over the passed two years, and the technology continuously improves with
each year.
Webcam Implementation
A major factor contributing to the popularity of webcams is their ease of use. Low
level webcams can be implemented with plug-and-play interfaces, whereas the slightly
higher quality cameras (such as those used for surveillance) require specific mounting
[4]. For under $20, specific mounting brackets are also available to lock in cameras at a
given location while $5 custom filters allow cameras to record clear images in even the
darkest or lightest of conditions.
Home-use webcams can simply be hardwired to a computer, whereas cameras
used for closed circuit video must rely on either wireless data transmission or lengthy
hardwired interfaces. The latter is usually achieved with standard 50’ optical wiring
(commonly priced at $15) whereas the wireless setup often requires multiple units such
as transmitters, receivers, and assorted cables (valued at over $60). However, wireless
systems can be used to manage multiple webcam inputs, whereas hardwired interfaces
can not. Thus, small businesses with multiple webcam networks find it economically
feasible to implement the wireless technologies as opposed to hardwired connections.
[1]
Y. Pritch, Rav-Acha, and Gutman, Peleg, “Webcam Synopsis: Peeking Around
the World,” in IEEE 11th International Conference on Computer Vision 2007, Rio
de Janeiro, 2007, pp. 1-8.
[2]
IBM, “Audio Visual Speech Technologies,” IBM Research, 2008 [Online].
Available: www.research.ibm.com/mcs/index.html. [Accessed: Jan 18, 2009]
[3]
SD Webcam, “San Diego Wildfires Reveal Benefits of Remote Surveillance,” SD
Webcam: News, 2007 [Online]. Available:
www.sdwebcam.com/News/sd_firestorm_2007.htm. [Accessed: Jan 19, 2009]
[4]
“Webcam Home Surveillance,” Sep. 14, 2005. [Online]. Available:
www.pcmag.com/article2/0,2817,1858581,00.asp. [Accessed: Jan 18, 2009].
[5]
Salix Technology Co., Ltd, “PC Camera,” U.S. Patent D478922, August 26, 2003
[6]
Kabushiki Kaisha Toshiba, “Camera for Electronic Computers,” U.S. Patent
D394274, July 29, 1997.
[7]
S. Mann, Intelligent Image Processing. Toronto, ON: Wiley and Songs, 2001, pp.
384.
[8]
Fujifilm Corporation, “Web Camera and Method for Sending Moving Image,” U.S.
Patent 7333134, February 19, 2008.
[9]
“Phillips SPC230NC/27 Data Sheet,” Nov. 11, 2008. [Online]. Available:
http://www.p4c.philips.com/files/s/spc230nc_27/spc230nc_27_pss_aen.pdf.
[Accessed: Jan 17, 2009]