One of surveillance's biggest challenges is bright sunlight, especially when that sunlight shines into a building's entrance. Sunlight tends to wash out images, often making it impossible to determine the person entering. Unfortunately, capturing people as they enter your building is one of the best and most effective ways of conducting video surveillance.
Camera manufacturers offer a variety of technologies to rectify this problem. The general name given to them is Wide Dynamic Range or WDR. By design, WDR should provide accurate image capture of both dark areas (e.g., shadows covering a person's face) and adjacent bright areas.
However, there are no standards nor easy way to figure out if one WDR function is better than another. While there is a metric for measuring dynamic range (dBs, e.g., 65 dB or 110 dB WDR), each manufacturer can choose their own measuring methodology so comparisons are basically pointless. (This is similar to the problem with determining low light performance. Manufacturers provide minimum illumination measured in lux but using a variety of conflicting metrics.)
In this report, we conducted a series of tests to better understand WDR performance using 3 well known manufacturers - Pixim, a chip manufacturer specializing in WDR, Axis and Sony. For Pixim, we tested 2 cameras - a March dome using the new Seawolf Pixim chip and an ioimage camera using the traditional Orca Pixim chip. For Axis, we used the P1347. For Sony, we used the SNC-CH140.
[UPDATED: We have done additional WDR shootouts focusing on megapixel cameras.]
We wanted to understand how different WDR featuresets and varying resolutions impacted overall image usability.
Inside the PRO section, we break down comparative performance and provide recommendations on tradeoffs and options.