Understanding Webcam Technology Lingo
Today, webcam technology is quite advanced and good webcams have the ability to capture both high quality (high definition) video as well as take great pictures. However, not all webcams are made equally, so below we explain some of the key differences and provide some clarity on terminology.
HD - High Definition
When a web camera is described as being HD 720p or HD 1080p it means that it delivers high-definition resolution. A 720p camera is an abbreviation for 1280x720 pixels of resolution, where 1280 represents the number of horizontal pixels and 720 represents the number of vertical pixels; therefore a 720p webcam will deliver a total of 921,600 pixels (or 0.9 MP or megapixels).
A 1080p camera, such as the Coralsix CW-201 model, is a much better camera, with 1920x1080 pixels of resolution, where 1920 represents the number of horizontal pixels and 1080 represents the number of vertical pixels, thus a total of 2,073,600 pixels (2.1 MP or megapixels). The “p” following the 1080 is short for “progressive scanning”. The quality of the video will be better when more pixels can be progressively scanned onscreen.
Now, sometimes a webcam is described as HD and sometimes it is described in terms of the number of megapixels. So, is a HD 1080p camera always the same as a 2.1MP camera? Not exactly. HD webcams described in terms of 720p or 1080p resolution, have an aspect ratio of 16:9, which is a widescreen view. Cameras that have a normal aspect ratio (picture as tall as wide) will often be described by the number of megapixels.
Finally, VGA cameras with a 640x480 resolution are normally less expensive entry-level cameras, are not high definition and use earlier technology.
Image sensors inside the webcam can be either CMOS (Complementary Metal–Oxide–Semiconductor) or CCD (Charge - Coupled Device). Both technologies were developed roughly at the same time, and there are many debates as which technology is better, but both sensors can certainly deliver high definition resolution, and technology continues to improve.
Another important common attribute to describe webcams is the frame rate, defined as frames per second or FPS. The higher the frame rate, the more fluid the streaming video will be. A good FPS rate for a 1080p webcam should be at least 30 FPS.
Lens Focus and FOV
There are a couple of options when it comes to the ability to focus the image on a lens. Some webcams are equipped with manual focus, thus the lens that can be manually moved in and out to focus the camera. However, we prefer the Coralsix CW-201 fixed-auto-focus lens. This lens has a sufficiently large depth of field that the use of a fixed-focus lens does not impact the image sharpness to a great extent, and it makes it much easier for the user as no adjustments are needed when moving closer or further from the camera.
FOV stands for Field of View, which is the part of the image that is visible through the camera, measured in angle degrees. Anything above 75-80 Deg is considered a wide-angle lens. However, sometimes, a camera with an FOV above 100 Deg can generate what is called a “fish eye” effect as the camera is attempting to capture a wide area within the lens.
Digital video streams deliver huge amounts of data during transmission from the image sensor, where the data is continuously created. Because of that, most webcams will have a built-it ASIC to do video compression in real-time and transmit each image. In a webcam like the Coralsix CW-201, the images are transmitted via USB compressed as MJPEG.
Good webcams will also include a number of features such as built-in microphones to make video calling and videoconferencing more convenient. The Coralsix WC-201 built-in mic is multidirectional with noise reduction and echo cancellation. Finally, another feature to consider is the USB interface with video device class (UVC) specification, allowing inter-connectivity to computers without the need for proprietary device drivers (i.e., no software installation needed).