This note discusses a video camera capability called Wide Dynamic Range (WDR), how this capability affects the quality of image, and how to measure this capability.

WDR is an image processing technique.  It enables image details of a certain range of light intensity levels to be displayed.  In a typical 24 hour day, various conditions exist such as reflections, glare, car headlights, and direct sunlight and they will make image capturing and display difficult.  WDR addresses this issue. When an exposure begins, each pixel is charged at a rate that is proportional to the intensity of the light that strikes it. A stronger light source will charge a pixel more quickly than a weaker light source. At the end of the exposure, the camera will sense the total charge accumulated in each pixel. But that means some pixels (the brighter ones) may be overexposed while others (the darker ones) may be underexposed. Dynamic range is the ratio of the brightest image that can be captured by the imaging system to the darkest image that can be captured. Light intensity greater than the brightest possible image will cause the sensor to saturate, while light intensity less than the darkest possible image will not register on the sensor. Both of these conditions distort the image, hiding potentially vital information that lies outside the dynamic range of the sensor.
WDR is a ratio and expressed in decibel.  A decibel (dB) is one tenth of a bel (B), that is, 1B = 10dB. The bel represents a ratio between two power quantities of 10:1, and a ratio between two field quantities of √10:1.  A field quantity is a quantity such as voltage, current, sound pressure, electric field strength, velocity and charge density, the square of which in linear systems is proportional to power. A power quantity is a power or a quantity directly proportional to power, e.g., energy density, acoustic intensity and luminous intensity.  The calculation of the ratio in decibels varies depending on whether the quantity being measured is a power quantity or a field quantity.
Convention adopted by Compucon for their camera models:                  Standard     60dB          1,000                  Advanced    80db          10,000                  Superior      100db        100,000                  Extreme      120db        1,000,000           Models CAB67 (indoor dome) and CAB87 (outdoor dome) were among the first           batch to have Superior WDR.