With the recent proliferation of integrated notebook webcams, designers today face the challenge of balancing the actual consumer need vs. marketing seesaw. Webcams risk heading down a path similar to DSCs: the drive for more pixels (higher resolution) when there really isn't a compelling need for one. In reality, going down this route can severely degrade the end-user experience because packing more pixels into smaller sensors translates into smaller pixels, which dramatically decreases low-light performance.
Currently, chat programs like AIM, Yahoo, Windows Live Messenger, and ICQ do not support high-resolution web conferencing or video chatting because of very limited broadband infrastructure, so webcam designers should not rush to design in the highest resolution webcams where there is no real application need.
This article will suggest that notebook PC OEMs take a step back and ask themselves whether they are designing with the right considerations in mind to optimize the end-user experience. It will discuss key issues related to integrating webcams into consumer notebooks, including how to maximize the performance attributes which really affect image quality: size, low light performance, resolution, and frame rate, while keeping in mind the limited broadband infrastructure and the typical applications/environment in which consumers operate their webcams.
Walk down memory lane with digital still cameras
The average consumer was first introduced to the idea of mega pixels when digital still cameras (DSCs) took off in the late 90's into the early millennium. A consumer who owned a DSC during this period was the center of attention in his group of friends. At the time, the subject of conversation was on what DSCs could do and how convenient they were compared to traditional 35mm film cameras. Fast forward to 2004, the casual user had already become comfortable with using DSCs and was starting to compare one camera's mega pixels to the next when shopping for a new camera. At the beginning of this trend, migrating quickly from VGA to 1.3MP to 2MP and then 3MP did benefit the end users because they would realistically print pictures in 4x6 or 5x7. As camera vendors started packing in more pixels than realistically needed (4MP and more), consumers began to mistakenly associate the number of pixels with the actual picture quality of the camera.
Perhaps this happened because it was a quantitative metric that consumers can grasp and compare, or it was simply the result of great marketing by the DSC vendors, functioning as a tool for differentiating their products. Few consumers understand that more mega pixels are only necessary if pictures need to be blown up for editing or developing large prints. From the surface, this may not appear to be a big problem as consumers get to pay less for more mega pixels over time, except now they are brainwashed to take the same approach when evaluating integrated webcams in their notebooks. Notebook PC vendors are glad to feed the fire and give consumers what they were trained to look for. Ultimately, this can be detrimental to the consumer experience because of the degradation of image quality in higher mega pixel webcams. Integrated notebook webcam designers need to consider many other important factors beyond mega pixels to most improve the end user experience.
Understanding the typical user environment for integrated notebook webcams
There are two typical characteristics about the environment in which consumers use integrated notebook webcams:
1) Over the internet on IM chat clients and
2) In unfavorable lighting conditions like the home or office.
Designers must consider these characteristics when designing integrated notebook webcams.
The internet and the world of instant messaging
Let's first look at the Internet and IM environment. Notebook PC vendors are rushing to integrate webcams as online instant messaging (IM) achieves critical mass. AOL Instant Messenger (AIM), Yahoo! Instant Messenger (YIM), Windows Live Messenger and ICQ are the most popular IM clients that support video based chatting. All chat clients use the Internet as the medium to connect users from a few doors down the neighborhood to relatives and business counterparts across the globe. While the Internet is powerful enough to connect users across the globe, it presents one major restriction to the performance of a webcam: limited bandwidth. A corollary to limited bandwidth is the fact that different users have varying connection speeds. IM clients take this into account by compressing already low-resolution video down to manageable sizes to transport through the Internet for the average connection speed.
At the time when video conferencing over webcams on IM clients was first introduced back in 2003, the average consumer broadband connection speed was on the order of 384kbps down / 128kbps up. To compare this in context with webcams, consider Apple's popular iChat software which supports AIM, ICQ, Jabber, and .MAC protocols, which uses cutting edge H.264 compression to deliver MPEG-2 quality video over the web at half the data rate. Even with using such high compression technology, Apple's iChat requires a minimum 100kbps up/down bandwidth to squeeze VGA resolution video through the Internet at 30FPS. At a glance, the 384kbps down / 128kbps up average broadband speed appears to suffice, but factoring in simultaneous usage of email, web browsing, and the physical distance between users across the globe, suddenly 384kbps down / 128kbps up seems barely sufficient. Over the past few years, the average broadband speed has inched up to averaging between 384-768kbps down and 128-384kbps up, which is less than two times the bandwidth increase.
On the other hand, integrated notebook webcams were introduced at VGA resolution by well known notebook PC vendors like Sony and Asus in 2004. By 2005, other notebook PC vendors began to introduce webcams, but skipping VGA altogether and immediately entering the market with 1.3MP cameras. The additional bandwidth requirement increased ~4 times going from VGA to 1.3MP. Comparing this to the increase of broadband speed adoption, which is ~2 times, integrated notebook webcams seem to be outpacing the broadband infrastructure in terms of bandwidth requirement. The advance of integrated notebook webcams up the mega pixel curve is simply not feasible.
While VGA and 1.3MP are still the dominant resolution in 2006, notebook PC vendors are already designing in 2.0 mega pixel cameras. Will consumers adopt the 2x or 3x bandwidth required within the next year or two? It seems unlikely, as broadband adoption overall is leveling off at 53% (Source: Pew Internet Project Survey, May 2005) in 2006 and internet service providers charge a tremendous premium for high upload speeds. Analysts predict that even if adoption rate increases, the speeds will stagnate or even decrease on average as more fierce competition drive the low cost packages down.
The home and office setting for webcams
Now, let's evaluate the typical environment where a user operates his webcam: in a home or office. The typical camera flash emits 2000 watts of light to properly expose a picture. A typical home or office environment uses lighting from 100 to 150 watt light bulbs, perhaps with multiple bulbs. This order of magnitude difference illustrates that users are operating webcams in unfavorable lighting conditions.
Image sensor vendors do all sorts of tricks like decreasing frame rate to maximize integration time and using pixel binning to accumulate additional light from neighboring pixels in order to improve low light performance. This generally works when taking still image captures, but when capturing video, these methods severely hurt frame rate and affect clarity of the picture.
Targeting the webcam specifications that matter
Mechanical Constraints: This is probably where the designer really starts from and needs to choose a webcam architecture that will meet the size constraints put on by the laptop bezel, while satisfying performance requirements. For example, given a very small bezel, perhaps low light performance will be compromised and the designer will need to choose an architecture that maximizes pixel area and pixel size. The different architectures are described below.
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