Dealing with direct sunlight is one of video surveillance's toughest problems. Avoiding the sun is frequently impossible. Making things worse, when a scene has direct sunlight creating both dark and bright areas, image quality can suffer dramatically.
In video surveillance, the technical term used to describe a camera's ability to handle these conditions is WDR or Wide Dynamic Range. In this context, range refers to the variations of light levels that a camera can capture and deliver a quality image. The greater the range, the more likely the camera can handle both very bright and dark areas (e.g., sunlight on a person's face, shadow on the car in the corner).
Earlier this year, we did our first WDR shootout with (2) SD and (2) MP cameras. One of the clear, yet surprising, results was that cameras with more pixels (i.e., megapixel) tended to outperform (i.e., capture more image details) than standard resolution cameras, even if the SD cameras were marketed as supporting WDR.
Given those results, in this test, we wanted to learn more about the differences in megapixel camera WDR performance. To do so, we tested 6 Megapixel cameras from Arecont Vision (AV1315), Axis (P1344), Panasonic (WV-SP306 and WV-NP502), Sony (CH140) and Vivotek (IP8151P) to see who was the best and worst at handling WDR scenes.
[UPDATE 2012: We have tested the Axis Q1604 against the best performing WDR cameras in this group.]
We picked 2 common real world scene:
- Doorway entrance facing outdoors - this is a common pain point for users who cannot properly identify individuals coming inside for hours a day as the sun faces the door
- Sun setting in the line of sight of an outdoor camera - this is a frequent problem for parking lot and street surveillance. Accidents or thefts occurring during those times of day can be obscured by the sun.
In addition to testing core WDR performances, we did additional testing of 2 advanced features to see what benefits they provide:
- Face WDR: Panasonic has an optional feature that can detect faces and then adjusts exposure to maximize the image quality of the detected face.
- Exposure Regions: A number of cameras, including Arecont and Axis, support exposure regions that allow lighting to be optimized for a specific area of the scene (e.g. region specified for where faces normally appear).
Below is a preview of our test results from the doorway showing fairly dramatic differences among the 6 megapixel cameras tested:
Inside the Pro section, we share full results and rankings of each camera's doorway performance.
Below is a preview of our test results from the outdoor setting sun scene showing major performance differences among the 6 megapixel cameras tested:
Inside the Pro section, we share full results and rankings of each camera's setting sun performance.