Webcam Image Quality

Joe asks, Is there software on the market that will produce a full screen image using a webcam? I've moved overseas and would like to remain with my family in the States. I have hesitated to purchase a webcam because I'm told that the picture produced is only about 4 inches by 4 inches regardless of the size of the screen. Is the situation hopeless?

Several factors determine onscreen size of a video image produced by a Webcam. The actual Webcam hardware may be limited to a maximum resolution. The percentage of your screen filled by a Webcam image will be a factor based on your desktop resolution and the maximum resolution of the Webcam image. A third factor impacting image size is available bandwidth Webcam software may also play a role in determining image size, but in most cases the software is only limited by the Webcam output. There are several ways to optimize your results to make sure you send a Webcam image viewable at the highest resolution acceptable to relatives on the other end, while also optimizing your system to maximize available screen real estate with inbound images from relatives.

Webcam hardware is often a big limiting factor in determining maximum image size. Most Webcams on the market today output a maximum 640x480 image, which easily fills a television screen. Any of the Webcams currently available from Logitech, Creative, Apple, D-Link or the numerous niche companies marketing Webcams will support 640x480, although some produce better results than others. If you have a Digital Video camera capable of doubling as a Webcam, you may get a 720x480 maximum image size. Apple's iSight camera and some of the higher end Logitech cameras using CCD instead of CMOS image sensors produce excellent images at 640x480 in well-lit rooms.

Knowing 640x480 is the maximum image size, don't expect incoming video to fill your screen if you have your resolution at 1024x768. The graphic below is shows the relative portion of a 1024x768 screen filled by a 640x480 image at 50% of actual size. If you want the incoming video to fill your screen, reset the resolution of your monitor to 640x480 to properly accommodate the incoming video feed. This assumes your relatives are capable of sending 640x480 video from their end. If their sending limitation is 320x240, the best you can hope for is a video filling 50% of your 640x480 screen.

Available bandwidth also plays a role in the size and quality of video image you can send or receive. If both you and the relatives back home are on broadband of some kind, you may be able to send 640x480 video, but it may require compromising the number of frames per second sent to avoid buffering. Full motion digital video is roughly 30 frames per second. Depending on the video format used under optimal network conditions you would need a bare minimum of 512 kbps upload speed to send a full motion 640x480 video to a single viewer and still have a video worth watching. While some cable providers are starting to offer upload speeds in the 512 kbps range and most DSL providers offer 768 kbps upstream, you will almost never get optimal network conditions for sending your video. There are two ways to deal with this: shrink the overall resolution of the video and keep the frame rate or keep the resolution and cut the frame rate in half. By cutting the frame rate to 15 fps, family members start looking choppy, but you still see them filling your screen, although even cutting the frame rate may not be enough to get a consistent network connection to work. People in the video compression business get paid large sums of money to figure out ways to optimize video delivery for maximum viewing size, frame rate and quality. In most cases, they work around these issues by requiring a buffer time to transfer part of the video before it starts playback, which doesn't work well for communication in real time.

All of these factors make software a minor part of the issue and certainly not the most limiting factor in the equation. Rather than sacrificing seeing loved ones back home, my recommendation would be to spend the $50 required to purchase a decent Webcam, drop your screen resolution to 640x480 before initiating a video conference session and then figuring out what the maximum video size your network will bear. If it means the video only fills 50% of your screen because some of the factors are working against you, at least you'll still be able to maintain a small link between you and loved ones across the globe.