Auto Exposure / Auto White Balance (DM36x processor only)

The DM365 and DM368 support the H3A hardware accelerator for supporting auto white balance (AWB) and auto exposure (AE). CMOS or CCD sensor video capture quality can be enhanced with AWB and AE image processing:

  • Auto exposure performs automatic adjustments of the image brightness according to the amount of light that reaches the camera sensor.

  • Auto white balance automatically compensates color differences based on lighting so white actually appears white.

Some camera sensors don't include auto white balance and/or auto exposure processing, so RidgeRun offers a library with AE and AWB algorithms called librraew.

The H3A engine divides the frames into two-dimensional blocks of pixels referred to as windows. The engine provides image/video metrics:

  • Accumulation of clipped pixels along with all non-saturated pixels in each window on a per color basis.

  • Accumulation of the sum of squared pixels per color.

  • Minimum and maximum pixel values in each window on a per color basis.

Auto Exposure / Auto White Balance (DM36x processor only) allows you to easily test the main features of the boards listed below. 

Platforms Supported



The DM36x H3A engine can be configured to use up to 36 horizontal windows with sum + {sum of squares or min+max} output or up to 56 horizontal windows with sum output. The H3A engine can also be configured to use up to 128 vertical windows. The width and height for the windows are programmable.


The librraew library was tested using an Aptina MT9P031 CMOS sensor. Support for other sensors was added later, thus validating the librraew design. If you provide the appropriate sensor-specific functions for the library, it can work with any sensor. The implementation is a plain C library and can be re-used with and integrated with any application capable of making C function calls. Image Pipe Daemon uses librraew to provide auto exposure/Auto white balance.

Learn more

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