CAMERA & VIDEO FUNDAMENTALS

Resolution Tutorial

• Resolution means the ability to resolve details__________________________________________________________• For analog camera resolution was measured with line counts,

literally the camera's ability to display more lines side by side in a given area on a monitor.

• If you could see more lines, it meant you could see more real world details – facial features, characters, license plates, etc.

__________________________________________________________• For digital camera resolution has been redefined as counting the

number of physical pixels that an image sensor has.• Pixels are a necessary, but not sufficient, factor for capturing details.

Resolution Tutorial

• The presumption is that more pixels, delivers higher ‘quality’. • Is that true?• Having many more pixels can result in poorer resolving power in low

light conditions. • Cameras with lower pixel counts but superior image processing can

deliver higher quality images in bright sunlight /WDR scenes.• The table below summarizes the most common resolutions used in

production video surveillance deployments today:

Resolution Tutorial

• Manufacturers typically specify cameras based on the resolution (i.e. pixel count) of the sensor, sometimes, the resolution of the stream sent can be less.

• 5MP sensor may be used but only a 2MP max output stream is available.

Resolution Tutorial• Each pixel is assigned a value to represent its color, typically out of a

range of ~16 million (24 bits), creating a huge amount of data. • For instance, a 1080p/30fps uncompressed stream is over 1Gb/s. • However, with digital video today, surveillance video is almost always

compressed. • That 1080p/30fps stream would more typically be recorded at 1Mb/s

to 8Mb/s – 1/100th to 1/1000th less than the uncompressed stream.• How much compression loss can be tolerated often depends on

subjective preferences of viewers or the details of the scene being captured.

• Equally important, increasing compression can result in great cost saving on hard drive, switch and server reductions.

Resolution TutorialAngle of Incident:

• Even if the image on the left had 10x the pixels as the one on theright, the left one is incapable of seeing the full facial details of the subject.

Resolution Tutorial

Factors Impacting Resolution:

• Low light performance• WDR performance• Compression settings• Camera angle / down tilt• Lens selection and focus

Conclusion: Do not accept specified resolution (i.e. pixel count) as the one and only quality metric as it will result in great problems.

Pixels Determine Potential, Not Quality

• Clearly as we increased pixels allocated, the more fine details that can be captured.• This is what we mean by pixels determine potential.