Exposure Control

Exposure is the amount of light that reaches the webcam sensor. It is an important part of how bright or dark your image appears.

Exposure varies directly with the amount of time that the shutter is open, allowing light to enter and reach the sensor. So, the interface ExposureControl uses a single value of duration, in units of time that you specify, typically TimeUnit.MILLISECONDS.

For example, at a frame rate of 60 frames per second (fps), exposure duration is 1/60 of a second, or 1/60 x 1000 = 16 milliseconds. This basic tutorial does not address frame rate.

Here are the methods to manage exposure:

• setExposure() has two parameters: duration and time unit

• getExposure() has one parameter: time unit

The webcam may support minimum and maximum allowed values of exposure. These can be retrieved with:

• getMinExposure(TimeUnit.MILLISECONDS)

• getMaxExposure(TimeUnit.MILLISECONDS)

There are no set() methods for min and max exposure; these are hard-coded in the webcam’s firmware. Note that firmware settings may vary among different versions of the same webcam model.

These and other exposure methods are called on an ExposureControl object; sample code is shown below, after Exposure Control Mode.